128748-02820 PORPHYRIA DISEASE MODELS REFERENCE TO RELATED APPLICATIONS This application claims priority to International Application No. PCT/CN2022/126116, filed on October 19, 2022, the entire contents of which are incorporated herein by reference. S ^EQUENCE L ^ISTING The instant application contains a Sequence Listing which has been submitted electronically in XML format and is hereby incorporated by reference in its entirety. Said XML copy, created on October 18, 2023, is named 128748_02820_Sequence_Listing.xml and is 62,583 bytes in size. B ^ACKGROUND Heme is an essential molecule to almost all organisms. Heme functions as a prosthetic group on several types of proteins, including cytochromes, catalases, hemoglobin, and myoglobin. Moreover, it has been reported that heme is also involved in numerous regulatory systems in mammals (Kubota et al., J. Bio. Chem., 291(39): 20516-20529, 2016). Production of heme and heme precursors are regulated by 5-aminolevulinate synthases (e.g., ALAS2). ALAS2 is known as 5'-aminolevulinate synthase 2, 5-aminolevulinic acid synthase 2, or ^- aminolevulinic acid synthase 2. Inhibition of ALAS2 or reduction in ALAS2 protein level may reduce heme pathway flux and suppress the production of toxin metabolites in the heme pathway. The blood disorder erythroid porphyria is caused by mutations in one or more enzymes in the heme pathway. Erythroid porphyrias are characterized by acute photosensitivity resulting in painful attacks, due to pathologically elevated or accumulated erythrocyte porphyrins. At least three subtypes of erythroid porphyria are known: X-linked protoporphyria (XLP or XLPP), erythropoietic protoporphyria (EPP), and congenital erythropoietic porphyria (CEP). SUMMARY In certain aspects, the disclosure relates to a mouse (Mus musculus) as an animal model for X-linked protoporphyria (XLP), wherein the mouse comprises an insertion of a polynucleotide encoding the amino acid sequence of SEQ ID NO: 10 directly upstream of an AGTG site in at least one 5-aminolevulinic acid synthase 2 (ALAS2) locus of the mouse, wherein the AGTG site corresponds to positions 1715 to 1718 of SEQ ID NO: 9, and the polynucleotide encoding the amino acid sequence of SEQ ID NO: 10 comprises a stop codon 1 ME146394007v.1 128748-02820 at its 3’ end. In some embodiments, the polynucleotide encoding the amino acid sequence of SEQ ID NO: 10 comprises the nucleic acid sequence of SEQ ID NO: 11. In some embodiments, the mouse is heterozygous for the insertion. In some embodiments, the mouse is homozygous for the insertion. In some embodiments, the mouse is a female. In some embodiments, the mouse is male. In some embodiments, the mouse is generated by CRISPR/Cas9-mediated homology-directed repair (HDR) that introduces the insertion into the ALAS2 locus. In some embodiments, a single guide RNA (sgRNA) encoded by the nucleotide sequence of SEQ ID NO: 12 or SEQ ID NO: 13 is used for the CRISPR/Cas9- mediated HDR. In certain aspects, the disclosure relates to a mouse (Mus musculus) as an animal model for erythropoietic protoporphyria (EPP), wherein the mouse comprises one or more genomic mutations in at least one endogenous Ferrochelatase (FECH) gene that results in an M98K substitution relative to the amino acid sequence of SEQ ID NO: 1 in a FECH protein encoded by the gene. In some embodiments, the one or more genomic mutations is a T293A substitution relative to the nucleic acid sequence of SEQ ID NO: 2. In some embodiments, the mouse is homozygous for the one or more genomic mutations in the FECH gene that results in the M98K substitution. In some embodiments, the mouse is heterozygous for the one or more genomic mutations in the FECH gene that results in the M98K substitution. In some embodiments, the mouse comprises the genomic DNA sequence of SEQ ID NO: 5. In some embodiments, the mouse is generated by CRISPR/Cas9-mediated homology-directed repair (HDR) that introduces the one or more genomic mutations into the endogenous FECH gene. In some embodiments, a single guide RNA (sgRNA) encoded by the nucleotide sequence of SEQ ID NO: 14 is used for the CRISPR/Cas9-mediated HDR. In some embodiments, the CRISPR/Cas9-mediated HDR utilizes a donor DNA having the polynucleotide sequence of SEQ ID NO: 15. In some embodiments, the mouse further comprises (i) at least one expression cassette comprising a polynucleotide encoding a reverse tetracycline-controlled transactivator (rtTA) under transcriptional control of a Rosa26 promoter and (ii) at least one expression cassette comprising a polynucleotide encoding an ALAS2 shRNA sequence (shALAS2) under transcriptional control of a TRE promoter. In some embodiments, the expression cassette comprising a polynucleotide encoding an rtTA is inserted into chromosome 6. In some embodiments, the expression cassette comprising a polynucleotide encoding shALAS2 is inserted into chromosome 11 at the ColA1 locus. 2 ME146394007v.1 128748-02820 In some embodiments, the mouse is heterozygous for rtTA (rtTA+/-), and heterozygous for shALAS2 (shALAS2+/-). In some embodiments, the mouse is homozygous for rtTA (rtTA+/+), and homozygous for shALAS2 (shALAS2+/+). In some embodiments, the shALAS2 comprises the sequence UGAAAAAUUGGUCAUAACCGAA (SEQ ID NO: 16). In certain aspects, the disclosure relates to a mouse (Mus musculus) as an animal model for erythropoietic protoporphyria (EPP), wherein the mouse comprises an insertion of a fragment of intron 3 of a human Ferrochelatase (FECH) gene at a first FECH genomic locus of the mouse, wherein the fragment is inserted at the 3’ end of intron 3 of the mouse FECH gene such that the mouse FECH gene retains the splice donor site in intron 3, and the fragment comprises a T1658C substitution relative to the human FECH gene intron 3 nucleic acid sequence of SEQ ID NO: 3, and wherein the mouse further comprises a loss-of-function mutation in a FECH gene at a second FECH genomic locus. In some embodiments, the fragment of intron 3 of the human FECH gene is 156 bp. In some embodiments, the fragment of intron 3 of the human FECH gene comprises the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the mouse comprises the nucleic acid sequence of SEQ ID NO: 8. In some embodiments, the mouse is generated by CRISPR/Cas9-mediated homology- directed repair (HDR) that introduces the fragment of intron 3 of the human FECH gene into the first FECH genomic locus of the mouse. In some embodiments, a single guide RNA (sgRNA) encoded by the polynucleotide sequence of SEQ ID NO: 21 and an sgRNA encoded by the polynucleotide sequence of SEQ ID NO: 22 are used for the CRISPR/Cas9-mediated HDR. In some embodiments, the CRISPR/Cas9-mediated HDR utilizes a donor DNA having the polynucleotide sequence of SEQ ID NO: 8. In some embodiments, the loss-of-function mutation in the FECH gene at the second FECH genomic locus is a knockout of the FECH gene. In some embodiments, the FECH gene at the second FECH genomic locus comprises a premature stop codon. In some embodiments, the premature stop codon results from a CCCGAAA deletion at the second FECH genomic locus. In some embodiments, the knockout of the FECH gene at the second FECH genomic locus is generated by CRISPR/Cas9-mediated homology-directed repair (HDR). In some embodiments, a single guide RNA (sgRNA) encoded by the nucleotide sequence of SEQ ID NO: 23 is used for the CRISPR/Cas9-mediated HDR. In some embodiments, the mouse has a reduced level of hemoglobin compared to a syngeneic wild-type mouse. In some embodiments, the mouse is a male. In some embodiments, the 3 ME146394007v.1 128748-02820 mouse is a female. In some embodiments, the mouse is a C57BL/6 mouse. In some embodiments, the mouse exhibits increased skin lesion formation upon exposure to light compared to a syngeneic wild-type mouse. In some embodiments, the mouse has an elevated level of blood protoporphyrin IX (PPIX) and/or Zn-PPIX compared to a syngeneic wild-type mouse. In certain aspects, the disclosure relates to an immortalized human CD34 ⁺ blood cell comprising a genomic insertion of an exogenous polynucleotide encoding an shRNA targeting a human Ferrochelatase (FECH) gene. In some embodiments, the polynucleotide encoding the shRNA comprises the nucleic acid sequence of SEQ ID NO: 17. In certain aspects, the disclosure relates to an immortalized human CD34 ⁺ blood cell comprising a genomic insertion of an exogenous polynucleotide encoding an shRNA targeting a human Uroporphyrinogen III Synthase (UROS) gene. In some embodiments, the polynucleotide encoding the shRNA comprises the nucleic acid sequence of SEQ ID NO: 18. In some embodiments, the blood cell comprises a heterologous polynucleotide encoding C- Myc and a heterologous polynucleotide encoding Bcl-xL. In some embodiments, the heterologous polynucleotide encoding C-Myc and the heterologous polynucleotide encoding Bcl-xL are operably linked to an inducible promoter. In some embodiments, the inducible promoter is a doxycycline-inducible promoter. BRIEF DESCRIPTION OF THE DRAWINGS FIG.1 shows a schematic of the heme biosynthesis pathway. Mutations in heme biosynthetic enzymes result in accumulation of phototoxic heme pathway metabolites such as protoporphyrin IX and copro/uroporphyrin I. FIG.2 shows a schematic of the insertion into the mouse ALAS2 gene used to create the mouse ALAS2-delAGTG model. A 71-bp synthetic sequence (SEQ ID NO: 11) encoding a mutant human ALAS2 protein sequence (SEQ ID NO: 10) was inserted 5’ to the AGTG site in exon 11 of the mouse ALAS2 gene (SEQ ID NO: 9, encoding SEQ ID NO: 24) by CRISPR. The sequence of the 71 bp insertion is shown at the bottom of the figure, and the mouse ALAS2 gene AGTG insertion site is shown underlined. A guanosine (G) residue 5’ to 4 ME146394007v.1 128748-02820 the insertion site in the mouse ALAS2 gene combines with the first two guanosine residues in the 71 bp insertion to form the GGG codon for glycine. FIG.3 shows elevated blood protoporphyrin IX (PPIX) and zinc protoporphyrin IX (Zn- PPIX) levels in a ALAS2-del AGTG mouse model. FIG.4 shows a CRISPR knock-in design used to generate the FECH-M98K mouse model. The italicized nucleotides are silent mutations to create the unique restriction sites, which are underlined in the figure, for genotyping. The wildtype (WT) mouse FECH gene is provided as SEQ ID NO: 7, and the WT mouse FECH protein as SEQ ID NO: 1. The sequence of the fragment of the mouse FECH gene containing the M98K mutation is SEQ ID NO: 39, and the corresponding fragment of the mouse FECH protein containing the M98K mutation is SEQ ID NO: 40. FIG.5 shows elevated blood protoporphyrin IX (PPIX) levels in a FECH ^M98K/M98K mouse model. FIG.6 shows hyper skin sensitivity to light for the FECH ^M98K/M98K mouse model. FIG.7 shows doxycycline (dox)-inducible ALAS2 knockdown in shRNA2 ^+/+ mice and the gene dosage effect of a doxycycline (dox)-inducible ALAS2 shRNA in mice. FIG.8 shows that knockdown of ALAS2 by a doxycycline (dox)-inducible ALAS2 shRNA in a FECH-M98K erythropoietic protoporphyria (EPP) mouse model reduced blood protoporphyrin IX (PPIX) levels without statistically significantly affecting hemoglobin (HGB) levels. FIG.9 illustrates a strategy to generate the FECH IVS mutation by CRISPR. FIG.10 shows possible aberrant mRNA splicing in FECH IVS mutants. Splicing products 2- 3-ab4 and 2-3-4 resulted in the desired FECH-IVS model. Splicing pattern 2-4 resulted in the undesired complete skipping of intron 3. FIG.11 shows RT-PCR analysis of homozygous (homo) and heterozygous (Het) FECH IVS mutants. FECH-IVS mutation resulted in an abnormal splicing of FECH mRNA equivalent to that seen in EPP patients. Exon 3 skipping was not observed. 5 ME146394007v.1 128748-02820 FIG.12 shows FECH mRNA expression in the FECH-IVS mouse model as determined by qPCR. FECH-IVS mutation decreased FECH mRNA levels in liver tissue and bone marrow. FIG.13 shows FECH protein expression in the FECH-IVS mouse model as determined by western blot. FECH-IVS mutation decreased FECH protein levels in liver tissue and bone marrow. FIG.14A shows an alignment of the wildtype mouse FECH DNA sequence (nucleotides 201- 250 of SEQ ID NO: 2) and the mouse FECH knockout (KO) containing a CCCGAAA deletion generated by CRISPR. Figure 14B shows an alignment of the first 100 amino acid residues of the wildtype mouse FECH protein (SEQ ID NO: 1), and the mutated mouse FECH (if translated) protein (SEQ ID NO: 42). If translated, the mouse FECH KO protein is expected to have a premature stop codon (*). FIG.15A and 15B show blood and bone marrow protoporphyrin IX (PPIX levels), respectively, in a FECH ^IVS/- mouse model. FIG.15C shows bone marrow 5-aminolevulinic acid (5-ALA) levels in a FECH ^IVS/- mouse model. FIG.16 shows hemoglobin (HGB) levels in a FECH-IVS/KO mouse model. The FECH- IVS/KO mice exhibit mild anemia. FIG.17 shows skin lesions in FECH-IVS/KO mice exposed to light. FIG.18A and FIG.18B show that Dox-inducible expression of c-myc/bcl-xL keeps hematopoietic stem cells in an arrested state of differentiation, as measured by CD71 and CD235. Removal of dox resulted in resumed differentiation similar to primary (non- immortalized) CD34 ⁺ cells. Figure 18B depicts the entire time-course of FACS sample analysis from days 0 to 10 for IMD and primary CD34 ⁺ cells with values obtained for IgG-PE and IgG-APC controls and IgG-CD71 and IgG-CD235 in the same plots. Figure 18A separates IgG controls and CD71 and CD235-specific data into separate plots for timepoints 0 and 10 days +/- dox. FIG.19 shows that Dox-inducible expression of c-myc/bcl-xL retains conditionally immortalized hematopoietic stem cells in the basophilic stage of differentiation. FIG.20 shows a disease-relevant model of erythropoietic protoporphyria (EPP) in IMD CB CD34 ⁺ cells. Lentiviral-mediated knockdown of the FECH protein using short hairpin RNA 6 ME146394007v.1 128748-02820 842 in IMD-CD34 ⁺ cells resulted in accumulation of PPIX in the cell culture media after 24 hours, as measured by fluorescence, compared to the non-targeting control (NT). FIG.21 shows that transient knockdown of ALAS2 blocks PPIX production in a disease- relevant model of EPP derived from erythroid-differentiating human CD34 ⁺ cells. FIG.22 shows a disease-relevant model of congenital erythropoietic porphyria (CEP) in IMD CB CD34 ⁺ cells. Lentiviral-mediated knockdown of the UROS protein using hairpin 524 in IMD-CD34 ⁺ cells resulted in accumulation of uroporphyrin (UROP) in the cell culture media after 24 hours, as measured by fluorescence, compared to the non-targeting control (NT). DETAILED DESCRIPTION The present disclosure provides in vivo and in vitro models for the study of disorders characterized by defects in the heme pathway. Defects in the heme pathway lead to accumulation of one or more physiological or non-physiological metabolites of the pathway such as 5-aminolevulinic acid (5-ALA) (also referred to as ^-aminolevulinic acid ( ^ALA)), porphobilinogen (BPG), hydroxymethylbilane (HMB), uroporphyrinogen I, uroporphyrinogen III (UROgen III), coproporphyrinogen I, coproporphyrinogen III (CPgenIII), protoporphyrinogen IX, uroporphyrin I, coproporphyrin I, heme, and protoporphyrin IX (PPIX). The defects in the heme pathway are attributed to the deregulation of one or more enzymes in the heme pathway. As shown in Figure 1, the enzymes in the heme pathway include ^- aminolevulinic acid synthase 2 (ALAS2), ALA dehydratase (ALAD), hydroxymethylbilane synthase (HMBS), uroporphyrinogen III synthase (UROS), uroporphyrinogen decarboxylase (UROD), coproporphyrinogen oxidase (CPOX), protoporphyrinogen oxidase (PPOX), and ferrochelatase (FECH). Examples of metabolites of the heme pathway are 5-aminolevulinic acid (also referred to as ^-aminolevulinic acid ( ^ALA)), porphobilinogen (BPG), hydroxymethylbilane (HMB), uroporphyrinogen I, uroporphyrinogen III (UROgen III), coproporphyrinogen I, coproporphyrinogen III (CPgenIII), protoporphyrinogen IX, uroporphyrin I, coproporphyrin I, heme, and protoporphyrin IX (PPIX). In some embodiments, the disorder characterized by defects in the heme pathway is associated with deregulated wild-type ALAS2. 7 ME146394007v.1 128748-02820 In some embodiments, the disorder characterized by defects in the heme pathway is caused by mutations in one or more enzymes in the heme pathway (see examples of the enzymes given above). In one embodiment, the mutated enzyme is ALAS2. In another embodiment, the mutated enzyme is FECH. In yet another embodiment, the mutated enzyme is UROS. In further embodiments, the disorder characterized by defects in the heme pathway is associated with an increase in the amount and/or activity of ALAS2. In some embodiments, the disorder characterized by defects in the heme pathway is associated with a decrease in the amount and/or activity of FECH. In some embodiments, the disorder characterized by defects in the heme pathway is associated with a decrease in the amount and/or activity of UROS. One class of such disorders are blood disorders known as porphyria, erythroporphyria, or erythoid porphyria. Porphyrias are characterized by acute photosensitivity resulting in painful attacks, due to pathologically elevated or accumulated erythrocyte porphyrins. At least three subtypes of porphyria are known: X-linked protoporphyria, erythropoietic protoporphyria, and congenital erythropoietic porphyria. X-linked protoporphyria (XLP or XLPP) is caused by gain-of-function (GOF) mutations in 5- aminolevulinic acid synthase isoform 2 (ALAS2) (the first enzyme of the heme pathway as shown in Figure 1). These mutations increase ALAS2 enzymatic activity, leading to an increased pathway flux to such an extent that it overwhelms the capacity of the last enzyme in the pathway, which is ferrochelatase (FECH). As a result, the penultimate pathway intermediate, protoporphyrin IX (PPIX), cannot be processed and thus accumulates in the body. Erythropoietic protoporphyria (EPP) is caused by loss-of-function (LOF) mutations in FECH. Reduction in FECH activity creates a bottleneck that also results in accumulation of PPIX. EPP is characterized by cutaneous photosensitivity. See Tutois et al., J. Clin. Invest.88: 1730-1736, 1991, which is incorporated by reference herein in its entirety. PPIX, uroporphyrin I, and coproporphyrin I can be the molecular causes of these erythroporphyrias. These molecules are photo-excited when exposed to light in the skin, generating reactive species that cause intense pain and other features characteristics of these diseases. Therefore, reduction of these metabolites may help ameliorate the erythroporphyrias. 8 ME146394007v.1 128748-02820 Myelodysplastic syndrome associated with isolated del(5q) (Del5q MDS) or Diamond- Blackfan anemia (DBA) are rare disorders caused by defects in ribosomal proteins, which are important in protein translation. Heme production and globin protein synthesis are highly coordinated events during red cell maturation. However, due to the defects in ribosomal protein functions, the translation of globin proteins in Del5q MDS and DBA can be outpaced by the synthesis of heme, resulting in accumulation of toxic level of heme, which in turn inhibits erythropoiesis. Thus, the methods provided herein inhibiting heme production may help treating Del5q MDS or DBA. Congenital erythropoietic porphyria (CEP) is caused by loss-of-function mutations in uroporphyrinogen III synthase (UROS). Normally, UROS converts hydroxymethylbilane to uroporphyrinogen III, which is a physiological and direct product that can be further metabolized. Loss-of-function mutations of UROS cause a blockade at this enzymatic step, leading to accumulation of hydroxymethylbilane. Accumulated hydroxymethylbilane can undergo a non-enzymatic reaction to form uroporphyrinogen I and eventually uroporphyrin I or coproporphyrin I, which are both non-physiological and dead-end products that cannot be further metabolized, thereby resulting in their accumulation in the body. Another class of disorders that can be evaluated using the models described herein is anemia, which is a disorder associated with a deficiency of red blood cells (RBCs) and/or hemoglobin. In one embodiment, the anemia is further associated with deregulated ALAS2, examples of which include X-sideroblastic anemia. Yet another group of disorders that can be evaluated using the models described herein are disorders that are caused by defects in ribosomal proteins. Due to defects in ribosomal protein functions, the translation of globin proteins in these disorders is outpaced by heme synthesis, thereby resulting in accumulation of toxic levels of heme, which reduces erythropoiesis (i.e., production of RBCs). Examples of disorders that are caused by the defects in ribosomal proteins are in myelodysplastic syndrome (MDS) with isolated del(5q) and Diamond- Blackfan anemia. I. ALAS2-delAGTG Mouse Model of X-linked Protoporphyria (XLP) XLP (see NCBI MIM 300752, incorporated herein by reference) is an erythropoietic porphyria due to gain-of-function mutations in the ALAS2 gene, which is on the X chromosome. Two previously identified exon 11 small deletions, namely c.1699_1670ΔAT 9 ME146394007v.1 128748-02820 (ΔAT) and c.1706_1709ΔAGTG (ΔAGTG), have been identified to prematurely truncate or elongate the wild-type ALAS2 polypeptide, leading to increased ALAS2 enzymatic activity of about 20- to 40-fold, thus causing the erythroid accumulation of protoporphyrins, cutaneous photosensitivity, and liver disease. Three additional mutations, a frameshift mutation caused by a 26 bp deletion (c.1651–1677del26bp), c.1734ΔG (ΔG), and c.1642C>T (p.Q548X, a nonsense mutation), as well as an engineered deletion mutation, c.1670- 1671TC>GA p.F557X, were also expressed and characterized (Ducamp et al., Human Molecular Genetics 22(7): 1280–1288, 2013; Bishop et al., Mol. Med.19(1): 18-25, 2013). According to Bishop, compared to the purified wild-type enzyme, ΔAT, ΔAGTG and Q548X enzymes had increased specific activities that were 1.8-, 3.1- and 1.6-fold, respectively. Meanwhile, the elongated ΔG enzyme had wild-type specific activity, kinetics and thermostability; but twice the wild-type purification yield (56% versus 25%); suggesting greater stability in vivo. On the basis of studies of mutant enzymes, the maximal gain-of function region spanned 57 amino acids between 533 and 580. Overall, these ALAS2 gain- of-function mutations increased the specific activity (ΔAT, ΔAGTG and p.Q548X) or stability (ΔG) of the enzyme, thereby leading to the increased erythroid protoporphyrin accumulation causing XLP. In certain aspects, the disclosure relates to a mouse (Mus musculus) as an animal model for XLP, wherein the mouse comprises an insertion of a polynucleotide encoding the amino acid sequence of SEQ ID NO: 10 directly upstream of an AGTG site in at least one ALAS2 locus of the mouse, wherein the AGTG site corresponds to positions 1715 to 1718 of SEQ ID NO: 9, and the polynucleotide encoding the amino acid sequence of SEQ ID NO: 10 comprises a stop codon at its 3’ end. In some embodiments, the insertion of the polynucleotide encoding the amino acid sequence of SEQ ID NO: 10 corresponds to or recapitulates the human ALAS2-GOF mutation c.1706_1709ΔAGTG (ΔAGTG). In some embodiments, the polynucleotide encoding the amino acid sequence of SEQ ID NO: 10 and comprising a stop codon at its 3’ end is 71 bp in length. In some embodiments, the polynucleotide encoding the amino acid sequence of SEQ ID NO: 10 comprises the nucleic acid sequence of SEQ ID NO: 11. In some embodiments, the polynucleotide encoding the amino acid sequence of SEQ ID NO: 10 consists of the nucleic acid sequence of SEQ ID NO: 11. 10 ME146394007v.1 128748-02820 According to this aspect of the disclosure, the endogenous mouse ALAS2 gene is modified to mimic the genetic GOF mutation found in a human XLP patient, such as the human ALAS2- GOF mutation c.1706_1709ΔAGTG (ΔAGTG) mutation in an XLP human patient, in which the 4 nucleotides AGTG at nt.1706 to 1709 are deleted. The mutation can be introduced into a mouse zygote using any art-recognized means, such as CRISPR/Cas-mediated gene editing, or introduced into a mouse ES (embryonic stem) cell via traditional homologous recombination. In some embodiments, the mouse has an elevated level of blood protoporphyrin IX (PPIX) and Zn-PPIX compared to a syngeneic wild-type mouse. In further embodiments, the mouse is an inbred strain of mouse, such as C57BL/6 mouse. In some embodiments, the mouse is a male, which is hemizygous for the mutation on the X chromosome (ALAS2 ^delAGTG/Y ). In other embodiments, the mouse is a female, which can be heterozygous or homozygous for the mutation. In some embodiments, the mouse is homozygous for the genomic ALAS2- delAGTG mutation (ALAS2 ^{delAGTG/delAGTG} ). In other embodiments, the mouse is heterozygous for the genomic ALAS2-delAGTG mutation (i.e., the female mouse comprises one wild-type allele of ALAS2) (ALAS2 ^delAGTG/WT ). In further embodiments, the mouse is generated by CRISPR/Cas9-mediated homology- directed repair (HDR). In still further embodiments, the CRISPR/Cas9-mediated HDR is carried out by microinjecting into the pronucleus of a mouse zygote an mRNA encoding Cas9, an sgRNA, and a single-stranded DNA (ssDNA) (e.g., all at a concentration of 10 ng/µL). In some embodiments, a CRISPR/Cas9 coding sequence (e.g., Cas9 mRNA), its single guide RNA (sgRNA) targeting an ALAS2 sequence for generating a double-stranded break (DSB) to facilitate homology-directed repair (HDR) using a donor DNA (e.g., a single-stranded donor DNA) harboring the desired sequence change, and the donor DNA, can be introduced together into the nucleus of a mouse zygote by, for example, microinjection or electroporation. Upon synthesis of the Cas9 enzyme in the zygote, the sgRNA is loaded onto the Cas9 effector enzyme to generate a DSB, which can be repaired by HDR using the sequence in the donor DNA. 11 ME146394007v.1 128748-02820 The zygote (e.g., a zygote for a male mouse) having such mutation on the X chromosome is then allowed to develop to term in a surrogate female to generate the founder male mouse and the female mouse (which can be homozygous or heterozygous for the mutation). Subsequent crossing of the male and/or female founders to the background strain produces female progenies that are homozygous or heterozygous and male progenies that are hemizygous for the mutation. The presence of mutations can be verified through genotyping using standard technology, such as PCR using genomic DNA isolated from tails and toes. In some embodiments, the single guide RNA (sgRNA) for CRISPR/Cas9 is encoded by the nucleotide sequence of SEQ ID NO: 19 or the nucleotide sequence of SEQ ID NO: 20. In further embodiments, the CRISPR/Cas9-mediated HDR utilizes a donor DNA having the polynucleotide sequence of SEQ ID NO: 11. In still further embodiments, the CRISPR/Cas9- mediated HDR utilizes a donor DNA from an XLP patient (e.g., a mouse or a human patient). II. FECH-M98K Mouse Model of Erythropoietic Protoporphyria (EPP) A methionine to lysine substitution at position 98 in the mouse FECH protein (mutation M98K) reduces FECH activity. See Tutois et al., 1991, cited above; and Boulechfar et al., Genomics 16(3): 645-648, 1993. The M98K mutation was first identified in mice in a chemical mutagenesis experiment with ethylnitrosourea (ENU). Affected animals exhibit a mild anemia with a high reticulocyte count, photosensitivity, and dramatic hepatobiliary dysfunction with jaundice from the early days of life onwards. Mice homozygous for the M98K FECH mutation display normocytic anemia, photosensitivity, cholestasis, and severe hepatic dysfunction. In the homozygotes, protoporphyrin is found at high concentration in erythrocytes, serum, and liver, and ferrochelatase activity in various tissues is 2.7-6.3% of normal. Mice heterozygous for the M98K FECH mutation are not anemic and have normal liver function. The heterozygotes are not sensitive to light exposure, and ferrochelatase activity is 45-65% of normal. See Tutois et al., 1991, cited above. In certain aspects, the disclosure relates to a mouse (Mus musculus) as an animal model for EPP, wherein the mouse comprises one or more genomic mutations in at least one endogenous FECH gene that results in an M98K substitution relative to the amino acid sequence of SEQ ID NO: 1 in a FECH protein encoded by the gene. 12 ME146394007v.1 128748-02820 Any one or more genomic mutations that result in an M98K substitution in the mouse FECH protein may be used. The methionine at position 98 of the mouse FECH protein is encoded by the codon ATG at positions 292-294 of the mouse FECH nucleic acid sequence of SEQ ID NO: 2. Lysine may be encoded by the codon AAG or AAA. Accordingly, in some embodiments, the genomic mutation is a T293A substitution relative to the nucleic acid sequence of SEQ ID NO: 2, which results in the codon AAG encoding lysine. In some embodiments, the genomic mutations are a T293A substitution and a G294A substitution relative to the nucleic acid sequence of SEQ ID NO: 2, which result in the codon AAA encoding lysine. In some embodiments, the mouse is homozygous for the one or more genomic mutations in the FECH gene that results in the M98K substitution. In other embodiments, the mouse is heterozygous for the one or more genomic mutations in the FECH gene that results in the M98K substitution. In some embodiments, the mouse comprises the genomic DNA sequence of SEQ ID NO: 5. In further embodiments, the FECH M98K mutant mouse is generated by CRISPR/Cas9- mediated homology-directed repair (HDR). In still further embodiments, the CRISPR/Cas9- mediated HDR is carried out by microinjecting into the pronucleus of a mouse zygote an mRNA encoding Cas9, an sgRNA, and a single-stranded DNA (ssDNA) (e.g., all at a concentration of 10 ng/µL). In some embodiments, a CRISPR/Cas9 coding sequence (e.g., Cas9 mRNA), its single guide RNA (sgRNA) targeting a FECH sequence for generating a double-stranded break (DSB) to facilitate homology-directed repair (HDR) using a donor DNA (e.g., a single-stranded donor DNA) harboring the desired sequence change, and the donor DNA can be introduced together into the nucleus of a mouse zygote by, for example, microinjection or electroporation. Upon synthesis of the Cas9 enzyme in the zygote, the sgRNA is loaded onto the Cas9 effector enzyme to generate a DSB, which can be repaired by HDR using the sequence in the donor DNA. The zygote having such mutation is then allowed to develop to term in a surrogate female to generate the founder male mouse and the female mouse (which can be homozygous or heterozygous for the mutation). Subsequent crossing of the male and/or female founders to 13 ME146394007v.1 128748-02820 the background strain produces progeny that are homozygous or heterozygous for the mutation. The presence of mutations can be verified through genotyping using standard technology, such as PCR using genomic DNA isolated from tails and toes. In some embodiments, the single guide RNA (sgRNA) for CRISPR/Cas9 is encoded by the nucleotide sequence of SEQ ID NO: 14. In further embodiments, the CRISPR/Cas9- mediated HDR utilizes a donor DNA having the polynucleotide sequence of SEQ ID NO: 15. In some embodiments, the mouse is a C57BL/6 mouse. In some embodiments, the mouse is a male. In other embodiments, the mouse is a female. III. FECH-M98K + shALAS2 Mouse Model The FECH-M98K mutant mouse model described above may be combined with a mouse model comprising a doxycycline-inducible shRNA targeting ALAS2 (shALAS2). The shALAS2 mouse model is described in WO2020/247819, which is incorporated by reference herein in its entirety. The shALAS2 mouse model expresses the following shRNA sequence to target mouse ALAS2: UGAAAAAUUGGUCAUAACCGAA (SEQ ID NO: 16). This shALAS2 mouse line carries the expression cassette of the reverse tetracycline-controlled transactivator (rtTA) under a Rosa26 promoter on chromosome 6. In addition, the expression cassette for the ALAS2-shRNA (shALAS2) under the TRE promoter was knocked into chromosome 11 at the ColA1 locus. Expression of ALAS2 shRNA could be induced by treatment of the mice with doxycycline in food to knock down ALAS2 expression. The following symbols are used to described mice carrying these two transgenes: rtTA ^+/- (heterozygous); rtTA ^+/+ (homozygous); shALAS2 ^+/- (heterozygous); shALAS2 ^+/+ (homozygous). In some aspects, the disclosure relates to a mouse (Mus musculus) comprising: a) one or more genomic mutations in at least one endogenous Ferrochelatase (FECH) gene that results in an M98K substitution relative to the amino acid sequence of SEQ ID NO: 1 in a FECH protein encoded by the gene; b) at least one expression cassette comprising a polynucleotide encoding a reverse tetracycline-controlled transactivator (rtTA) under transcriptional control of a Rosa26 promoter; and c) at least one expression cassette comprising a polynucleotide encoding an ALAS2 shRNA sequence (shALAS2) under transcriptional control of a TRE promoter. 14 ME146394007v.1 128748-02820 In some embodiments, the expression cassette comprising a polynucleotide encoding an rtTA is inserted into chromosome 6. In some embodiments, the expression cassette comprising a polynucleotide encoding shALAS2 is inserted into chromosome 11 at the ColA1 locus. In some embodiments, the mouse is heterozygous for rtTA (rtTA+/-) and heterozygous for shALAS2 (shALAS2+/-). In other embodiments, the mouse is homozygous for rtTA (rtTA+/+), and homozygous for shALAS2 (shALAS2+/+). In some embodiments, the ALAS2 shRNA comprises the sequence UGAAAAAUUGGUCAUAACCGAA (SEQ ID NO: 16). In some embodiments, the ALAS2 shRNA consists of SEQ ID NO: 16. IV. FECH-IVS/KO Mouse Model for Erythropoietic Protoporphyria (EPP) More than 85 mutations in the FECH gene have been identified in human EPP patients. Most individuals who are heterozygous for these mutations are asymptomatic, despite having FECH activity levels that are only half the normal value. For protoporphyrin to accumulate ^{sufficiently to cause photosensitivity, FECH activity has to fall below a critical threshold of} _{about 35% of the normal level. Human patients with the dominant form of EPP usually} share a hypomorphic FECH allele that is common in the general population in trans to a rare loss-of-function allele. A common intronic single nucleotide polymorphism (SNP), IVS3- 48C, is responsible for the low expression of the hypomorphic allele by modulating the use of a constitutive cryptic acceptor splice site. The aberrantly spliced mRNA is degraded by a nonsense-mediated decay mechanism, leading to a lower steady-state level of FECH mRNA. This low steady-state level of normal mRNA results in an additional FECH enzyme deficiency. In conjugation with the LOF mutation in the second allele, the overall FECH activity falls below the threshold value, resulting in accumulation of protoporphyrin and photosensitivity. See Gouya et al., Am. J. Hum. Genet.78: 2-14, 2006 which is incorporated by reference herein in its entirety. In certain aspects, the disclosure relates to a mouse (Mus musculus) as an animal model for EPP, wherein the mouse comprises an insertion of a fragment of intron 3 of a human FECH gene at a first FECH genomic locus of the mouse, wherein the fragment is inserted at the 3’ end of intron 3 of the mouse FECH gene such that the mouse FECH gene retains the splice donor site in intron 3, and the fragment comprises a T1658C substitution relative to the human FECH gene intron 3 nucleic acid sequence of SEQ ID NO: 3. 15 ME146394007v.1 128748-02820 In some embodiments, the fragment of intron 3 of the human FECH gene is 156 bp. In some embodiments, the fragment of intron 3 of the human FECH gene replaces a fragment of the mouse FECH gene of equal size, e.g., 156 bp. In some embodiments, the fragment of intron 3 of the human FECH gene comprises the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the fragment of intron 3 of the human FECH gene consists of the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the mouse comprises the nucleic acid sequence of SEQ ID NO: 8. In some embodiments, the mouse is generated by CRISPR/Cas9-mediated homology-directed repair (HDR) that introduces the fragment of intron 3 of the human FECH gene into the first FECH genomic locus of the mouse. In some embodiments, a single guide RNA (sgRNA) encoded by the polynucleotide sequence of SEQ ID NO: 21 and an sgRNA encoded by the polynucleotide sequence of SEQ ID NO: 22 are used for the CRISPR/Cas9-mediated HDR. In some embodiments, the CRISPR/Cas9- mediated HDR utilizes a donor DNA having the polynucleotide sequence of SEQ ID NO: 8. In some embodiments, the mouse further comprises a loss-of-function mutation in a FECH gene at a second FECH genomic locus. In some embodiments, the loss-of-function mutation in the FECH gene is a knockout of the FECH gene. In some embodiments, the FECH gene at the second FECH genomic locus comprises a premature stop codon. In some embodiments, the premature stop codon results from a CCCGAAA deletion at the second FECH genomic locus. In some embodiments, the knockout of the FECH gene at the second FECH genomic locus is generated by CRISPR/Cas9-mediated homology-directed repair (HDR). In some embodiments, a single guide RNA (sgRNA) encoded by the nucleotide sequence of SEQ ID NO: 23 is used for the CRISPR/Cas9-mediated HDR. In some embodiments, the FECH IVS mouse model has a reduced level of hemoglobin compared to a syngeneic wild-type mouse. In some embodiments, the mouse is a male. In other embodiments, the mouse is a female. In some embodiments, the mouse is a C57BL/6 mouse. In some embodiments of the mouse models described herein (e.g., a FECH-M98K mouse model of EPP or a FECH-IVS/KO mouse model), the mouse exhibits increased skin lesion 16 ME146394007v.1 128748-02820 formation upon exposure to light compared to a syngeneic wild-type mouse. In some embodiments of the mouse models described herein (e.g., an ALAS2-delAGTG mouse model of XLP, a FECH-M98K mouse model of EPP, a FECH-M98K + shALAS2 mouse model (before dox treatment), or a FECH-IVS/KO mouse model), the mouse has an elevated level of blood protoporphyrin IX (PPIX) and/or Zn-PPIX compared to a syngeneic wild-type mouse. V. Immortalized Human CD34 ⁺ Blood Cell Lines Expressing shRNAs Targeting FECH or UROS Immortalized human CD34 ⁺ blood cells may be prepared through inducible heterologous expression of c-Myc and B-cell lymphoma-extra large protein (Bcl-xL). The c-Myc gene is a proto-oncogene and encodes a nuclear phosphoprotein that plays a role in cell cycle progression, apoptosis and cellular transformation. Bcl-xL is a member of the Bcl-2 protein family and is a major survival factor responsible for the signal proerythroblasts must receive in order to survive and become red cells. Overexpression of c-Myc and Bcl-xL in multipotent hematopoietic progenitor cells derived from pluripotent stem cells enabled sustained exponential self-replication of glycophorin A+ erythroblasts. In an inducible expression system, turning off the overexpression of c-Myc and Bcl-xL enabled the self- replicating glycophorin A+ erythroblasts to mature. See Hirose et al., Stem Cell Reports 1: 499-508, 2013, which is incorporated by reference herein in its entirety. The immortalized human CD34 ⁺ blood cells described above may be used to prepare in vitro porphyria disease models through heterologous expression of shRNAs targeting the human FECH gene or the human UROS gene. As described herein, FECH is the last enzyme in the heme pathway, and reduction of FECH activity results in accumulation of PPIX, the penultimate heme pathway intermediate. Accordingly, immortalized human CD34 ⁺ blood cells expressing an shRNA targeting the FECH gene may be used as an in vitro model of EPP. In addition, as described herein, CEP is caused by loss-of-function mutations in UROS. Accordingly, immortalized human CD34 ⁺ blood cells expressing an shRNA targeting the UROS gene may be used as an in vitro model of CEP. In some aspects, the disclosure relates to an immortalized human CD34 ⁺ blood cell comprising a genomic insertion of an exogenous polynucleotide encoding an shRNA 17 ME146394007v.1 128748-02820 targeting a human FECH gene. In some embodiments, the polynucleotide encoding the shRNA targeting the human FECH gene comprises the nucleic acid sequence of SEQ ID NO: 17. In some embodiments, the polynucleotide encoding the shRNA targeting the human FECH gene consists of the nucleic acid sequence of SEQ ID NO: 17. In some aspects, the disclosure relates to an immortalized human CD34 ⁺ blood cell comprising a genomic insertion of an exogenous polynucleotide encoding an shRNA targeting a human UROS gene. In some embodiments, the polynucleotide encoding the shRNA targeting the human UROS gene comprises the nucleic acid sequence of SEQ ID NO: 18. In some embodiments, the polynucleotide encoding the shRNA targeting the human UROS gene consists of the nucleic acid sequence of SEQ ID NO: 18. In some embodiments, the immortalized human CD34 ⁺ blood cell comprises a heterologous polynucleotide encoding C-Myc and a heterologous polynucleotide encoding Bcl-xL. In some embodiments, the heterologous polynucleotide encoding C-Myc and the heterologous polynucleotide encoding Bcl-xL are operably linked to an inducible promoter. In some embodiments, the inducible promoter is a doxycycline-inducible promoter. EXAMPLES Example 1. Generation of an X-linked protoporphyria (XLP) mouse model containing an ALAS2-delAGTG mutation In humans, deletion of the AGTG nucleotides in exon 11 of the ALAS2 gene creates a translational frame shift resulting in a sequence replacement at the C-terminus of the protein, as shown below. 541 587 (SEQ ID NO: 24) hALAS2....TAVGLPLQDV SVAACNFCRR PVHFELMSEW ERSYFGNMGPQYVTTYA* del-AGTG..TAVGLPLQDV SVAACNFCRR PVHFELMSGN VPTSGTWGPSMSPPMPEKPA A* (SEQ ID NO: 25) 18 ME146394007v.1 128748-02820 Although the C terminal protein sequences of wildtype human and mouse ALAS2 are identical, deletion of the equivalent nucleotides AGTG in mice would not result in the same protein sequence replacement due to differences in codon usage. Methods To create a mouse ALAS2-delAGTG line that has the same C-terminal sequence observed in the human ALAS2-delAGTG mutant protein, a 71-bp synthetic sequence encoding the mutant human protein sequence was inserted 5’ to the mouse AGTG site by CRISPR. A schematic of the insertion is shown in Figure 2, with the sequence of the 71 bp insertion shown at the bottom of the figure, and the mouse AGTG insertion site underlined. A guanosine (G) residue 5’ to the insertion site in the mouse ALAS2 gene combines with the first two guanosine residues in the 71 bp insertion to form the GGG codon for glycine. To enhance editing efficiency, two gRNA sequences: ATGCTTAAGGAGCCAGCTGC (SEQ ID NO: 19) and CAATATGTTACCACCTATGC (SEQ ID NO: 20) were used. In addition, the donor template was composed of the inserted sequence flanked by ~1 kb long homologous sequences and provided in the form of a vector. C57BL/6 was chosen as the genetic background for this mouse line. Blood PPIX measurements: 10 µL of the blood sample was added to 190 µL acetonitrile:methanol:formic acid:water (40:40:10:10, v/v/v/v) , vortexed and centrifuged at 14000 rpm for 5 min.10 µL of the supernatant was mixed with 10 µL of acetonitrile:methanol:formic acid:water (40:40:10:10, v/v/v/v) and 200 µL of acetonitrile:methanol:formic acid (50:50:5, v/v/v) containing 2 ng/mL labeled-PPIX. Samples were mixed well and centrifuged at 5800 rpm, 4°C for 10 min.50 µL of supernatant was later mixed with 50 µL of 0.1% formic acid in methanol:water (1:1, v/v). An aliquot of 5 µL of mixture was injected into the UPLC-MS/MS system. The LC separation was carried out using a Thermo Hypersil Gold C8 (2.1×50 mm, 1.9 µm) set at 40 ⁰C with the following mobile phases: (A) 0.2% formic acid, methanol:water (1:1, v/v) and (B) 0.2% formic acid in acetonitrile:methanol:water (40:50:10, v/v/v). The mobile phase was maintained at 50% B for 0.5 mins and subsequently increased to 80% B in 1 min with a flow rate of 0.6 mL/min. Under these conditions, the retention time for PPIX was 1.54 min. The MRM transition, [M+H]+ m/z 563.60→431.40, was monitored for PPIX. Blood Zn-PPIX measurements: 19 ME146394007v.1 128748-02820 10 µL of the blood sample was added to 190 µL acetonitrile:methanol:water (40:40:20, v/v/v)-0.1% ammonia, vortexed and centrifuged at 14000 rpm for 5 mins.40 µL of the supernatant was added with 200 µL of acetonitrile:methanol (50:50, v/v) containing 5 ng/mL candesartan ciloexetil. Samples were mixed well and centrifuged at 5800 rpm, 4°C for 10 min.50 µL of supernatant was later mixed with 50 µL of methanol:water (1:1, v/v). An aliquot of 2 µL of mixture was injected into the UPLC-MS/MS system. The LC separation was carried out using a Thermo Hypersil Gold C8 (2.1×50 mm, 1.9 µm) set at 40 ⁰C with the following mobile phases: (A) 0.1% acetic acid in water and (B) 0.1% acetic acid in acetonitrile:methanol:water (40:50:10, v/v/v). The mobile phase was maintained at 20% B for 1 min, increased to 80% B in 0.7 min, and subsequently increased to 95% B in 1.3 mins with a flow rate of 0.6 mL/min. Under these conditions, the retention time for Zn-PPIX was 2.10 min. The MRM transition, [M+H]+ m/z 624.00→565.10, was monitored for Zn-PPIX. Results As shown in Figure 3, female mice heterozygous for the ALAS2-delAGTG mutation (ALAS2 ^delAGTG/WT ) exhibited elevated levels of blood PPIX and Zn-PPIX levels compared to a syngenic wild-type female mice (ALAS2 ^WT/WT ) and wild-type male mice (ALAS2 ^WT/Y ). Example 2. Generation of a FECH-M98K mutant mouse model of erythropoietic protoporphyria (EPP) Methods A C57BL/6 mouse line was custom ordered from Mirimus, Inc (NY; mirimus.com). The following gRNA and ssODN donor DNA were used to introduce an M98K mutation in the FECH gene of the C57BL/6 mice via CRISPR technology: gRNA sequence: GTGTCATGAGGTCTCGGTCCAGG (SEQ ID NO: 4) ssODN donor DNA sequence: TGGAGAAGTTCAAGACTTTCTTCAGAGGCTCTTTCTAGATCGTGACCTTAAGACA CTTCCCATTCAAAAGTAAGTTAAGCTTTGTGGAGGGTCGTGTGTGG (SEQ ID NO: 5) 20 ME146394007v.1 128748-02820 A schematic of the CRISPR knock-in design used to generate the M98K mutation in the mouse FECH gene is provided in Figure 4. The resultant mouse line harbored a M98K mutation in the FECH gene. To prevent DNA being cut after homology directed repair (HDR), and to provide an AflII restriction site for genotyping, several additional silent mutations were also introduced. The silent mutations are underlined in Figure 4. Genotyping: Genomic DNAs were amplified by PCR using the following two primers followed by digestion with AflII. Wildtype DNA would produce a single 611-bp fragment whereas M98K mutant DNA would yield two small fragments of 432 and 179-bp in length. gpFech-fw1-BglII: 5’ataagatctGAAAGCCAGACCTGCGTACT 3’ (SEQ ID NO: 26) gpFech-rev2-EcoR1: 5’ tatgaattcCTGGCTAACTGGCTCTCCTG 3’ (SEQ ID NO: 27) Blood PPIX measurements: 90 µL of candesartan Ciloexetil (125 ng/mL) in water:methanol:formic acid (50:50:2, v/v/v) was added to 10 µL of whole blood, followed by adding 400 µL acetonitrile:methanol:formic acid (50:50:5, v/v/v). Sample was mixed well at 1100 rpm for 5 min, followed by centrifugation at 4000 rpm for 10 min. An aliquot of 25 µL supernatant was mixed with 75 µL acetonitrile:methanol:formic acid (50:50:5, v/v/v) and 100 µL of methanol:water (50:50, v/v)-0.1% formic acid. An aliquot of 10 µL of mixture was injected into the UPLC-MS/MS system. The LC separation was carried out using a Thermo Hypersil Gold C8 (2.1×50 mm, 1.9 µm) set at 40 ⁰C with the following mobile phases: (A) methanol:water (50:50, v/v)-2% formic acid and (B) acetonitrile:methanol:water (40:50:10, v/v/v)-2% formic acid. The mobile phase was maintained at 50% B for 0.5 mins and subsequently increased to 80% B in 1 min with a flow rate of 0.6 mL/min. Under these conditions, the retention time for PPIX was 1.25 min. The MRM transition, [M+H]+ m/z 563.2→445.2, was monitored for PPIX. Light sensitivity assay Mice were anesthetized with isoflurane anesthesia via induction chamber at 3-5% isoflurane concentration and a 0.5 LPM flow rate. Once animals were unconscious the isoflurane was turned off and the chamber flushed for 10 seconds with oxygen. Animals were then transferred to a five patient isoflurane manifold that had been outfitted into an Ultraviolet Irradiation System by Tyler Research (Cat number UV-2) with five custom 24” fluorescent 21 ME146394007v.1 128748-02820 lamps (421 nm peak output, 40W) installed and maintained at 1-2% isoflurane at a 0.5 LPM flow rate. A warm water heating pad was provided underneath the animals within the chamber in order to maintain body temperature and artificial tears were placed on the eyes in order to keep the eyes moist. A defined area of the lower back end of the animals was pre- shaved with electric trimming clippers and/or treated with Nare to expose the skin the day before. All unexposed areas of the animals were covered with aluminum foil or a lab bench pad in order to expose only the skin area desired. Animals were exposed for 60 minutes with all five light bulbs turned on. After 60 minutes, the UV irradiator lamps and isoflurane were turned off and the animals removed from the nose cones and placed in their home cages and allowed to recover until they were awake and ambulatory. Animals were dosed subcutaneously with 4 mg/kg MeloxicamSR for potential pain relief as required and were monitored over several days for any signs of potential effect of the exposure. Results As shown in Figure 5, male and female mice homozygous for the FECH M98K mutation (FECH ^M98K/M98K ) exhibited elevated blood PPIX levels relative to wildtype mice. As shown in Figure 6, FECH ^M98K/M98K mice showed hyper skin sensitivity to light four days after exposure to 421 nm light for 1 hour relative to wildtype mice. These results indicate that FECH-M98K mice may be used as a model of EPP. Example 3. Generation of a FECH-M98K mutant mouse model of erythropoietic protoporphyria (EPP) further comprising a doxycycline-inducible shRNA targeting ALAS2 (shALAS2) Methods The FECH-M98K mutant mouse model described in Example 2 above was crossed with a mouse model comprising a doxycycline-inducible shRNA targeting ALAS2 (shALAS2). The shALAS2 mouse model is described in WO2020/247819, which is incorporated by reference herein in its entirety. To generate the shALAS2 mouse model, the following shRNA sequence was used to target mouse ALAS2: UGAAAAAUUGGUCAUAACCGAA (SEQ ID NO: 16). This mouse line carries the expression cassette of the reverse tetracycline- controlled transactivator (rtTA) under a Rosa26 promoter on chromosome 6. In addition, the expression cassette for the ALAS2-shRNA (shALAS2) under the TRE promoter was knocked into chromosome 11 at the ColA1 locus. Expression of ALAS2 shRNA could be 22 ME146394007v.1 128748-02820 induced by treatment of the mice with doxycycline in food to knock down ALAS2 expression. The following symbols are used to described mice carrying these two transgenes: rtTA ^+/- (heterozygous); rtTA ^+/+ (homozygous); shALAS2 ^+/- (heterozygous); shALAS2 ^+/+ (homozygous). The FECH-M98K mutant mouse model described in Example 2 above was crossed with the shALAS2 mouse model to generate a mouse line with the following genotype: FECH- M98K ^+/+ ; rtTA ^+/- ; shALAS2 ^+/- . This mouse model expressed the FECH-M98K mutation but also harbored one copy of the rtTA and shALAS2 transgene. Blood PPIX measurements were obtained following the procedure described in Example 1. Bone marrow ALA measurements Bone marrow samples were homogenized in PBS mixed with an internal standard solution (100 ng/mL ¹³ C ₅ , ¹⁵ N-5-aminolevulinc acid). ALA in the samples was derivatized with N- butanol and separated by LCMS-MS. The LC separation was carried out using a Thermo Hypersil Gold AQ column (3×100 mm, 3 µm) set at 40 ⁰C with the following mobile phases: (A) 0.2% formic acid in water and (B) 0.2% formic acid in methanol. The mobile phase was maintained at 20% B for 0.5 mins and subsequently increased to 95% B in 2 min and maintained at 95%B for an additional 1 min with a flow rate of 0.4 mL/min. Under these conditions, the retention time for Bu-5-aminolevulinic acid was 3.09 min. The MRM transitions, [M+H]+ m/z 188.10→114.00 and [M+H]+ m/z 194.00→120.00 were monitored for Bu-5-aminolevulinc acid and Bu- ¹³ C ₅ , ¹⁵ N-5-aminolevulinc acid, respectively. Hemoglobin measurements Whole blood was collected via cardiac puncture in EDTA-coated tubes and were analyzed using the ADVIA® 2120i hematology system. Isolation and western blot analysis of protein from bone marrow Mice were put on dox-containing chow to induce the expression of shALAS2. On days 4 and 16, mice were euthanized, and bone marrow from both femurs and tibias was harvested via centrifugation at 10,000 x g for 15 seconds at 4°C followed by snap freezing in liquid nitrogen. Preparation of protein for western blot analysis was performed by resuspending the bone marrow in NP40 lysis buffer + protease inhibitor followed by probe sonication for 10 seconds at 35%. Samples were then centrifuged at 14,000 rpm for 10 minutes at 4°C. Sample 23 ME146394007v.1 128748-02820 supernatant was collected and quantified using the BCA protein assay. Samples were prepared to 0.5ug/µL protein in Laemmeli buffer and 30 µL was separated via SDS-PAGE using a 4-12% Bis-Tris NuPAGE gel. Relative mouse ALAS2 protein levels in the bone marrow were then determined by immunoblotting for rabbit anti-ALAS2 (antibody made inhouse) and mouse anti-Actin antibody (Cell Signaling #3700) as shown in Figure 7. Results As shown in Figure 7, doxycycline treatment for four days was sufficient to reduce ALAS2 protein expression in mice homozygous for the ALAS2 shRNA (ALAS2 shRNA ^+/+ ) as determined by western blotting. As shown in Figure 7, one copy of the ALAS2 shRNA (ALAS2 shRNA ^+/- ) results in approximately 50% ALAS2 protein reduction relative to wildtype, while two copies of the ALAS2 shRNA (ALAS2 shRNA ^+/- ) result in approximately 90% ALAS2 protein reduction relative to wildtype. As shown in Figure 8, knockdown of ALAS2 by the dox-inducible ALAS2 shRNA in homozygous FECH-M98K mice (FECH ^M98K/M98K ) reduced blood protoporphyrin IX (PPIX) levels without statistically significantly affecting hemoglobin (HGB) levels. This suggests there is a therapeutic window for treating EPP with an ALAS2 inhibitor to reduce blood toxins without inducing anemia. Example 4. Generation of an erythropoietic protoporphyria (EPP) mouse model (IVS/KO) comprising an insertion of a fragment of intron 3 of a human Ferrochelatase (FECH) gene comprising a 48T/C mutation (IVS) at a first FECH genomic locus and a knockout (KO) of the mouse FECH gene at a second FECH genomic locus Methods The most common form of EPP in humans is a compound heterozygous genotype with a IVS3-48T/C mutation (referred herein as the IVS mutation) in one allele of FECH and a severe loss-of-function mutation in the second FECH allele. Figure 9 provides a schematic of the generation of the desired IVS mutation by CRISPR in the mouse line. Figure 10 illustrates schematically some possible mRNA splicing patterns investigated to mimic EPP as seen in human patients. The mRNA splicing pattern denoted as 2-4 in Figure 10 resulted in complete exon 3 skipping in the FECH-IVS mouse line and therefore would not mimic EPP 24 ME146394007v.1 128748-02820 as seen in human patients. Splicing pattern denoted as 2-3-ab4 in Figure 10 demonstrates that the insertion of the human FECH intron 3 fragment harboring the 48T/C mutation into the mouse genome as described triggers an aberrant FECH mRNA splicing event utilizing the cryptic acceptor site as seen in human EPP patients with the FECH IVS-48T/C mutation. Thus, the engineered mouse line is a suitable mouse model for EPP with the FECH-IVS- 48T/C mutation. Materials for microinjection: For insertion of intron 3 of human FECH comprising the 48T/C (IVS) mutation Two sgRNAs were used and were prepared as follows. Two PCR reactions were performed using plasmids containing the sgRNA sequences to generate templates for in vitro transcription with the following primers (gRNA sequences denoted as all caps): sgRNA-IVS-sg forward primer: 5’- ttaatacgactcactataggAGGCGCCTGACAATTCAGCAgttttagagctagaaatag- 3’ (SEQ ID NO: 28) Reverse primer: aaaagcaccgactcggtgccac (SEQ ID NO: 29) RA-sg#1 forward primer: 5’-ttaatacgactcactataggTCATTGGACACATAAGTGAGgttttagagctagaa atag- 3’ (SEQ ID NO: 30) Reverse primer: aaaagcaccgactcggtgccac (SEQ ID NO: 29) After purification, in vitro transcription was performed using the MEGAshortscript T7 kit and MEGAclear kit according to the protocol (Ambion). Cas9 mRNA was in vitro transcribed from pUC-cas9 vector using mMESSAGE mMACHINE T7 kit (Ambion). To introduce the mutation, a ssDNA oligo was made with a 156-nucleotide fragment of the human FECH intron 3 containing the IVS-48T/C mutation flanked on the 5’ end by 257 nucleotides homologous to mouse FECH intron 3 and on the 3’ end by 212 nucleotides homologous to mouse FECH exon 4 and a fragment of intron 4. ssDNA sequence is: cggggccaatcctggggcctcagctcaatggcagagtctttgcctagcaccacgagggcc cagcttcaggctcacagaaccaaaca 25 ME146394007v.1 128748-02820 ccaccgacaaaaccagtgcaggctttctgtgctttctcccctgattcttgttaggtgcag attcagcacgtaggatggtagctatcagcat cccagtcctgggtgtgaggtctccagagtgtgcaggatagagcacgtgtggagtgcaggg gtgagctctcagatccatgcCTGG CTATTGTCAATGACCTCAAGCTTCTGTTTTAAAGGCTTAATCTTGTTAGGCTCTCT AAAATTTTGCTTTTTTTCTTTTTTATTGAGTAGAAAACATTTCTCAGGCTGCTAAG CTGGAATAAAATCCACTTACCTGTATGTTAAATGATTTAGtaagctggcaccattcatcg ccaaa cgccgaacccccaaaattcaagagcagtatcgcagaatcggaggtggatcccccatcaag atgtggacttccaagcaaggagaagg catggtgaagctgctggatgagttatcccctgccacaggtgtgctcttcttcttagtgct gggctaggctcgttacagtaggactcagggt caggggtgga (SEQ ID NO: 8) The mouse sequence is shown in lowercase letters, the human FECH intron 3 fragment is shown in uppercase letters, and the bold underlined C is the IVS-48T/C mutation in human FECH intron 3. A schematic of the human intron 3 IVS mutant insertion is shown in Figure 9. RT-PCR analysis to assess splicing Total liver RNA was used as the template for cDNA synthesis. To examine whether exon 3 skipping occurred, primers ex2-F-S (5’-GGAGAAGGTACATCATGCCAAGAC-3’; SEQ ID NO: 31) and ex4-R-S (5’-CTGTGGCAGGGGATAACTC-3’; SEQ ID NO: 32) were used. To examine splicing pattern of exon 3 and exon 4 specifically, primer Ex3-F (5’- CCTCATGACACTTCCCATTCAA-3’; SEQ ID NO: 33) and primer ex4-R-S were used. PCR conditions are indicated in the table below: Steps Temperature Time Note I i i l ° i 26 ME146394007v.1 128748-02820 As a positive control for the detection of complete exon 3 skipping, cDNA isolated from a different engineered mouse line was used (i.e., the mRNA splicing pattern denoted as 2-4 in Figure 10. As discussed above, for the control, the entire mouse FECH intron 3 was replaced by the human FECH intron 3 (with the IVS3-48T/C mutation). This strategy is known to cause complete skipping of exon 3 during splicing. RT PCR and western blot of FECH expression Liver and bone RNAs were extracted and used as templates for cDNA synthesis. FECH mRNA expression was measured by qPCR (Mouse FECH probe, Mm01257645, Thermo; mouse B2M probe, Mm00437762_m1, Thermo). Total proteins were extracted from the bone marrow tissue and liver. Western blots were performed using an anti-FECH antibody from Protein Tech (14466-1-AP). Mouse FECH KO mutation The gRNA was prepared as follows. A PCR reaction was performed using a plasmid containing the sgRNA sequence to generate a template for in vitro transcription with the following primers (gRNA sequences denoted as all caps): forward primer: 5’-ttaatacgactcactataggGAACTTCTCCAAGGGTTTCGgttttagagctagaa atag- 3’ (SEQ ID NO: 34) Reverse primer: 5’-aaaagcaccgactcggtgccac-3’ (SEQ ID NO: 29) After purification, in vitro transcription was performed using the MEGAshortscript T7 kit and MEGAclear kit according to the protocol (Ambion). Cas9 mRNA was in vitro transcribed from pUC-cas9 vector using mMESSAGE mMACHINE T7 kit (Ambion). The INDEL generated had a CCCGAAA deletion, resulting in a premature stop codon (p.Glu79LeufsTer96). Figure 14A shows an alignment of the wildtype mouse FECH DNA sequence and the mutated mouse FECH gene containing the CCCGAAA deletion. Figure 14B shows an alignment of the amino acid sequences of the wildtype and mutated mouse FECH protein. Pronuclear injection: 10~15 C57BL/6 females (4-week-old) were injected with PMSG (5IU- 10IU) on day 1. 48 hours later, the mice were injected with HCG (5IU-10IU) and then housed with C57BL/6 male overnight. In the morning of day 4, female mice with copulation plugs were collected for zygote preparation. Zygote-cumulus complexes from the oviduct 27 ME146394007v.1 128748-02820 were collected from euthanized mice and suspended in hyaluronidase solution for several minutes until the cumulus cells fell off, which were then washed several times in M2 medium. The embryos were then placed in equilibrated M16 medium (medium covered with mineral oil) at 37℃ in a 5% CO ₂ incubator. Cas9 mRNA, sgRNA, and ssDNA (all 10 ng/µL) were injected into the pronucleus of the zygotes. Injected zygotes were then cultured in M16 or KSOM medium at 37℃ in a 5% CO ₂ incubator until two-cell stage, at which point they were implanted into the oviduct of pseudo-pregnant foster mothers at 0.5 dpc. The following symbols are used to describe mice carrying the human IVS-48T/C mutation and FECH KO as FECH ^IVS and FECH ^E3-KO , respectively. Genotyping: Genomic DNAs were extracted from tails and toes of the 7-day-old pups and used in PCR amplification of the sequence around the targeting site with the following two primers: CC25 AAACCAGTCACACACCTGAAGTGC (SEQ ID NO: 35) CC26 GGCTAGACTTGTCTGAGTGAGTGAG (SEQ ID NO: 36) The resultant PCR products were TA cloned and sequenced to identify F ₀ mice, which were back crossed with wildtype C57BL/6 mice to identify F1 mice with germline transmitted mutation. PPIX measurements For blood PPIX: 10 µL of the blood sample was added to 190 µL acetonitrile:methanol:formic acid:water (40:40:10:10, v/v/v/v), and then vortexed and centrifuged at 14000 rpm for 5 mins. The supernatant was used as the diluted blood sample. The dilution factor was 20. For bone marrow PPIX: the bone marrow sample was homogenized with 4 volumes (v/w) of homogenizing solution PBS for 30 seconds, with a dilution factor of 5. The homogenized bone marrow solution was then diluted with 4 volumes (v/w) of acetonitrile:methanol:formic acid:water (40:40:10:10, v/v/v/v), and vortexed and centrifuged at 14000 rpm for 5 mins. The supernatant was used as the diluted-homogenized bone marrow sample. The dilution factor was 25. The diluted blood sample or the diluted-homogenized bone marrow sample (10 µL) was mixed with 10 µL of acetonitrile:methanol:formic acid:water (40:40:10:10, v/v/v/v), and 200 28 ME146394007v.1 128748-02820 µL of acetonitrile:methanol:formic acid (50:50:5, v/v/v) containing 5 ng/mL candesartan ciloexetil. The sample was mixed, centrifuged at 5800 rpm, 4°C for 10 min.50 µL of the supernatant was then mixed with 50 µL of 0.1% formic acid in methanol:water (1:1, v/v). The samples were then separated by LC-MS. The LC separation was carried out using a Thermo Hypersil Gold C8 (2.1×50 mm, 1.9 µm) set at 40 ⁰C with the following mobile phases: (A) 0.2% formic acid, methanol:water (1:1, v/v) and (B) 0.2% formic acid in acetonitrile:methanol:water (40:50:10, v/v/v). The mobile phase was maintained at 50% B for 0.5 min, increased to 80% B in 1 min, and subsequently increased to 95% B in 0.5 mins with a flow rate of 0.6 mL/min. Under these conditions, the retention time for PPIX was 1.49 min. The MRM transition, [M+H]+ m/z 563.60→431.40, was monitored for PPIX. Bone marrow ALA measurements: Bone marrow samples were homogenized in PBS mixed with an internal standard solution (100 ng/mL ¹³ C5, ¹⁵ N-5-aminolevulinc acid). ALA in the samples was derivatized with N- butanol and separated by LCMS-MS. The LC separation was carried out using a Thermo Hypersil Gold AQ column (3×100 mm, 3 µm) set at 40 ⁰C with the following mobile phases: (A) 0.1% formic acid in water and (B) 0.1% formic acid in methanol. The mobile phase was maintained at 20% B for 0.5 mins and subsequently increased to 95% B in 2 min and maintained at 95%B for an additional 0.8 min with a flow rate of 0.4 mL/min. Under these conditions, the retention time for Bu-5-aminolevulinic acid was 2.8 min. The MRM transitions, [M+H]+ m/z 188.10→114.00 and [M+H]+ m/z 194.00→120.00 were monitored for Bu-5-aminolevulinc acid and Bu- ¹³ C5, ¹⁵ N-5-aminolevulinc acid, respectively. Hemoglobin measurements were obtained following the procedure described in Example 3. Light sensitivity assay On day 1, mice were anesthetized with isoflurane anesthesia. A defined area of the back of the animals was shaven with electric trimming clippers and treated with Nare to expose the skin. On Day 3, mice were exposed under anesthesia to a light source (ecoBright EB20C, 20W, 2200 lumens, 5700 Kelvin) for one hour. Effects of light exposure were documented daily up to 3 days post light exposure. 29 ME146394007v.1 128748-02820 Results Figure 11 shows RT-PCR analysis of homozygous (homo) and heterozygous (Het) FECH IVS mouse mutants. FECH-IVS mutation resulted in an abnormal splicing of FECH mRNA equivalent to that seen in EPP patients. Exon 3 skipping was not observed when only the 3’ end of mouse intron 3 was replaced with the human sequence. As shown in Figure 12, introduction of the human FECH-IVS mutation into mice decreased FECH mRNA levels in liver tissue and bone marrow in a statistically significant manner, as determined by qPCR. As shown in Figure 13, the FECH-IVS mice also exhibited decreased FECH protein levels in bone marrow and liver tissue as determined by western blot. As shown in Figure 15A and 15B, mice heterozygous for a knockout of the FECH gene (FECH ^WT/KO ), exhibited a slight increase in protoporphyrin IX (PPIX) levels relative to wildtype or mice harboring the FECH IVS mutation alone (FECH ^IVS/WT ) in whole blood (15A) and bone marrow (15B). However, the compound heterozygous FECH ^IVS/KO mice showed substantially higher level of PPIX both in the blood and the bone marrow, mimicking what is seen in EPP patients with the EPP- IVS3-48T/C mutation in one allele and a LOF mutation on the second FECH allele. As shown in Figure 15C, only female FECH ^IVS/KO mice exhibited increased levels of 5- aminolevulinic acid (5-ALA) in bone marrow relative to wildtype, the IVS mutant alone, or the FECH ^KO alone. As shown in Figure 16, the FECH ^IVS/KO mice exhibited mild anemia, as indicated by reduced hemoglobin levels (mean HGB in male WT 14.6 g/dL vs mean HGB in male FECH-IVS/KO 12 g/dL; mean HGB in female WT 14.7 g/dL vs mean HGB in male FECH-IVS/KO 12.6 g/dL). As shown in Figure 17, FECH-IVS/KO mice exhibited skin lesions when exposed to light. Example 5. Preparation and evaluation of reversibly immortalized (IMD) primary cord blood CD34 ⁺ cells expressing an shRNA against human FECH or human UROS for use as in vitro models of erythropoietic protoporphyria (EPP) or congenital erythropoietic porphyria (CEP), respectively Methods Immortalization of human CD34 ⁺ cells derived from cord blood Primary human CD34 ⁺ cells derived from cord blood (Stemcell Tech.) were cultured for 9 days in hematopoietic progenitor expansion medium DXF (Promocell). Erythroid differentiation was initiated by culturing the cells in SFEM II + Erythroid Expansion 30 ME146394007v.1 128748-02820 Supplement (Stemcell Tech.). On day one, erythroid differentiation conditional immortalization of CD34 ⁺ cells was performed using 400 k cells per 6-well tissue plate pre- coated with 10 mg/mL of Retronectin (Clontech). CD34 ⁺ cells were transduced with lentivirus for dox-inducible expression of C-Myc and Bcl-xL (pLVX-TetOne-Blasticidin: MYC-IRES-BCL-XL). Bcl-xL/c-Myc-blast virus was added to cells in the presence of 400 ng/mL doxycycline (Sigma Aldrich) and spun for 1 hour at 2500 rpm. Media was changed on the cells following 48 hours of lentiviral transduction and replaced with SFEM II + Erythroid Expansion Supplement containing 5ug/mL blasticidin (ThermoFischer). Following antibiotic selection, immortalization of cells was confirmed upon observing no change in the expression of erythroid differentiation markers CD71 and CD235 and cell size in the presence of doxycycline and increased expression of CD71 and CD235 and reduced cell size upon removal of doxycycline. PE Mouse Anti-Human CD235a, APC Mouse Anti-Human CD71, PE Mouse Anti-Human IgG, and APC Mouse Anti-Human IgG were obtained from eBiosciences. In vitro EPP and CEP cell models using immortalized (IMD) CD34 ⁺ cord blood cells The immortalized (IMD) CD34 ⁺ cells described above were transduced with lentivirus to introduce an shRNA against human FECH with a puromycin marker (shRNA encoding sequence: GCTTTGCAGATCATATTCTAA; SEQ ID NO: 17). These cells are referred to as IMD CD34 ⁺ -shFECH, and can be used as an invitro model of erythropoietic protoporphyria (EPP). In a separate experiment, the IMD CD34 ⁺ cells described above were transduced with lentivirus to introduce an shRNA against human UROS with a puromycin marker (shRNA encoding sequence: TCAGTGTATGTGGTTGGAAAT; SEQ ID NO: 18). These cells are referred to as IMD CD34 ⁺ -shUROS, and can be used as an invitro model of congenital erythropoietic porphyria (CEP). For PPIX and uroporphyrin compound testing cell assays, IMD CD34 ⁺ -shFECH and shUROS cells were removed from doxycycline treatment for 48 hours while differentiating in SFEM II + Erythroid Expansion Supplement. Cells were then cultured in RPMI + 10% FBS with compound for 24 hours and media was assayed for PPIX fluorescence (ex 410 and em 690) or uroporphyrin fluorescence (ex 400 and em 620). Cell viability was then determined 31 ME146394007v.1 128748-02820 via CellTiter-Glo assay (Promega). Data were background subtracted and normalized to values from DMSO-treated cells, which was arbitrarily set as 100%. These reversibly immortalized cell-based models provide a renewable source of cord blood CD34 ⁺ cells from a single donor. The measurable accumulation of PPIX and uroporphyrin in the IMD CD34 ⁺ -shFECH and IMD CD34 ⁺ -shUROS models, respectively, provide a disease- relevant biomarker for drug discovery efforts. Measurement of CD34 ⁺ differentiation in immortalized and primary erythroblasts Doxycycline was removed from immortalized CD34 ⁺ cord blood cells in culture. Immortalized and primary CD34 ⁺ cells were allowed to differentiate in SFEM II hematopoietic expansion medium (StemCell #09655) for 10 days. Total FACs analysis of erythroid differentiation markers for both IMD and primary CD34 ⁺ cells for CD71 and CD235 was performed at 0, 2, 3, 5, 6, and 10 days post-dox removal. Briefly, 100k cells were stained with mouse anti-CD235-PE and anti-CD71-APC antibodies or mouse anti-IgG-PE and mouse anti-IgG-APC antibodies (eBiosciences) in 0.1% BSA PBS. CD71 verse CD235 signal from 10k cells was collected using the BD FACS Canto II and analyzed using FlowJo software (Figures 18A and 18B). Figure 18B depicts the entire time-course of FACS sample analysis from days 0 to 10 for IMD and primary CD34 ⁺ cells with values obtained for IgG-PE and IgG-APC controls and IgG-CD71 and IgG-CD235 in the same plots. Figure 18A separates IgG controls and CD71 and CD235-specific data into separate plots for timepoints 0 and 10 days +/- dox. Cell smears were prepared by washing 1x10 ⁶ cells in PBS followed by resuspension in 15 µL of 50mg/mL BSA in PBS.5 µL of cell suspension was smeared on a glass slide and air dried overnight. Slides were then dipped in May-Grunwald stain for 5 minutes, 1x phosphate buffer for 1.5 minutes, 1:20 Giesma and 1x PBS for 20 minutes, and deionized (DI) water. Stained samples were left overnight to dry. A cover slip was then mounted over the slides using VectaMount. Nail polish was used to seal the mounted coverslip to the slide prior to pathological analysis (Figure 19). Measurement of ALAS2 knockdown and PPIX fluorescence in erythroid-differentiating human CD34 ⁺ cells 32 ME146394007v.1 128748-02820 CD34 ⁺ cells expressing a shRNA targeting FECH (as described in Example 5) were used in this study. Cells were treated with 0.1, 0.25, 1, 3, and 5 µM sdRNA targeting human ALAS2 (CGUCUGGUGUAGUAAUGAUU (SEQ ID NO: 37), purchased from Advirna) for 3 days. Measurement of medium PPIX fluorescence and western blots for cellular ALAS2 and actin were performed as described in Example 5. Results As shown in Figures 18A and 18B, dox-inducible expression of c-myc/bcl-xL keeps hematopoietic stem cells in an arrested state of differentiation, as measured by CD71 and CD235. Removal of dox resulted in resumed differentiation similar to primary (non- immortalized) CD34 ⁺ cells. As shown in Figure 19, dox-inducible expression of c-myc/bcl- xL retains conditionally immortalized hematopoietic stem cells in the basophilic stage of differentiation. As shown in Figure 20, lentiviral-mediated knockdown of the FECH protein (undetectable by western blot) using short hairpin RNA (shRNA) 842 in IMD-CD34 ⁺ cells resulted in significant accumulation of PPIX in the cell culture media after 24 hours, as measured by fluorescence, compared to the non-targeting control (NT), indicating that this cell line is a disease-relevant model of erythropoietic protoporphyria (EPP). Figure 21 shows that transient knockdown of ALAS2 blocks PPIX production in a disease-relevant model of EPP. Figure 22 shows that lentiviral-mediated knockdown of the UROS protein using short hairpin RNA (shRNA) 524 and 413 in IMD-CD34 ⁺ cells decreased UROS protein expression by 72% and 65%, respectively, relative to the untreated WT sample. Analysis of uroporphyrin (UROP) in the cell culture media after 24 hours, as measured by fluorescence, compared to the non-targeting control (NT), resulted in a Relative Fluorescence Unit (RFU) value of 2068666, 99576, and 29173 for shUROS-524, shUROS-413, and shNT, respectively. These data indicate that the shUROS-524 cell line is a more disease-relevant model of congenital erythropoietic porphyria (CEP) compared to the shUROS-413 cell line due to the shUROS-524 cell line’s greater degree of UROS protein knockdown and elevated UROP. Description of Sequences SEQ ID Description 33 ME146394007v.1 128748-02820 2 Nucleic acid sequence of mRNA encoding mouse FECH protein 3 Nucleic acid sequence of entire Intron 3 of the human FECH gene 3 e 34 ME146394007v.1 128748-02820 22 Nucleic acid sequence encoding gRNA used to introduce the fragment of intron 3 of the human FECH gene into the mouse FECH genomic locus in the FECH- e Sequences of the Disclosure SEQ ID NO: 1. Mouse FECH amino acid sequence, M98 shown in bold 10 20 30 40 50 MLSASANMAA ALRAAGALLR EPLVHGSSRA CQPWRCQSGA AVAATTEKVH 60 70 80 90 100 HAKTTKPQAQ PERRKPKTGI LMLNMGGPET LGEVQDFLQR LFLDRDLMTL 110 120 130 140 150 35 ME146394007v.1 128748-02820 PIQNKLAPFI AKRRTPKIQE QYRRIGGGSP IKMWTSKQGE GMVKLLDELS 160 170 180 190 200 PATAPHKYYI GFRYVHPLTE EAIEEMERDG LERAIAFTQY PQYSCSTTGS 210 220 230 240 250 SLNAIYRYYN EVGQKPTMKW STIDRWPTHP LLIQCFADHI LKELNHFPEE 260 270 280 290 300 KRSEVVILFS AHSLPMSVVN RGDPYPQEVG ATVHKVMEKL GYPNPYRLVW 310 320 330 340 350 QSKVGPVPWL GPQTDEAIKG LCERGRKNIL LVPIAFTSDH IETLYELDIE 360 370 380 390 400 YSQVLAQKCG AENIRRAESL NGNPLFSKAL ADLVHSHIQS NKLCSTQLSL 410 420 NCPLCVNPVC RKTKSFFTSQ QL SEQ ID NO: 2. mRNA encoding mouse FECH, translation start shown in bold atgctttcgg ccagcgccaa catggctgcg gccctgcggg ctgcgggcgc tctgctccgc 60 gagccgctgg tgcacggcag ctcaagggcc tgtcagccat ggaggtgcca gtcgggtgct 120 gcggtggcag ccaccacgga gaaggtacat catgccaaga ccaccaaacc ccaagctcaa 180 ccagaaagga ggaagccaaa aacgggcata ttgatgttaa acatgggagg ccccgaaacc 240 cttggagaag ttcaagactt tcttcagagg ctcttcctgg accgagacct catgacactt 300 cccattcaaa ataagctggc accattcatc gccaaacgcc gaacccccaa aattcaagag 360 cgcagaatcg gaggtggatc ccccatcaag atgtggactt ccaagcaagg agaaggcatg 420 gtgaagctgc tggatgagtt atcccctgcc acagcacctc acaaatacta tattggattc 480 cggtacgtcc atcccctgac agaagaggca attgaagaga tggagagaga tggactagag 540 agggccattg ctttcacaca gtatccacag tatagctgct ccaccacagg cagcagctta 600 aatgccattt acagatacta taacgaggtg ggccagaagc ccaccatgaa gtggagcaca 660 atcgacaggt ggcccacaca ccccctcctc atccagtgct ttgcagacca cattctgaaa 720 gagctgaacc attttccaga ggagaagaga agcgaggtgg tcattctgtt ttctgcccac 780 tccctgccga tgtctgttgt caacagaggg gacccctatc cccaagaggt aggagccact 840 gtccacaaag tcatggaaaa gctgggttac cccaacccct accgactggt ttggcagtcc 900 aaggttggtc cagtaccctg gttgggccct cagacagatg aggctatcaa agggctttgt 960 gagcggggga ggaagaacat cctcttggtt ccaatagcat ttaccagtga ccacattgag 1020 acgctctacg aactggatat tgaatactct caagtgttgg ctcagaagtg tggagctgag 1080 aacatcagaa gagcggaatc tcttaatgga aatccattgt tctccaaggc cctggctgat 1140 ctggtgcact cccacatcca gtccaacaag ctgtgctcca cgcagttgag tctgaactgt 1200 ccgctctgtg taaatcctgt ctgcaggaag actaaatcct tcttcaccag ccaacagctg 1260 tga 1263 SEQ ID NO: 3. Intron 3 of human FECH gene, site of IVS-48T/C mutation (T1658) shown in bold and underlined 36 ME146394007v.1 128748-02820 gtg agatatatat aaacacctca attataacct tggcactaca ttgacatgtg tctctcaatt ctgtagtttc aaaccagtaa atagttttaa tgcgtatctg gtaatggtta aacagcagca ttgttttctg ttggatatca gaaggatatg atatcagaaa attgcagggg gagagagcaa ataagttagt ggggattctc cttgagccct ttgctcccca gagccctgga aattgcagtt gtcttgacat agcctaggta cctttaaaga tttttaaaga tatatttgta cttgtcactt aacggctgat taacactcag ggaagcaatg attattattc atttgtacta taaatatgga ttgttgctgc ccttcttttc ctttcatcct tctttccctt cttccttctc tcctttttct ttcaaaatag atttctatta tgaaaaatta gtacatgcat gggataaaaa ctacaaatag tataaaagta attacagtaa aaggcaagtg tccctttcac cttgcactcc cagttatcca cctggaggaa agcgctgtta catccagaaa tagtccgtgc atatccaagc atacacatac atacacacac acacgcgcac atacatacat acacacatgc acaccccccc ccccacttcg ttacacaaat gtgaaggtac ttatgtacta tatttgaaac tttccttttt tttttttttt ttttttttta catacgtata catgtgccat gttggtgtgc tgcacccatt aactcgtcat ttacattagg tatatctcct aatgctatcc ctcccctctc cccccactcc acgataggcc ctggtgtgtg atgttcccct tcctgtgtcc aagtgttctc attgttcaat tcccacctat gagtgagaac atgcggtgtt tggttttttg tccttgtgat agtttgctga gaatggtggt ttccagcttc atccatgtcc ctacaaagga catgaactca tcccttttta tggctgcatt agtattccac attttcttaa tccagtctat cattgatgga catttgggtt ggttccaagt ctttgctgtt gtgaatgtgt aaacttaaca ctgtatcttg tttcataacg ttatatcgat atataggtct ggctcatttt ttgattacta tttagaactg catcatatgg ctgtaactta atttgtttaa tccatgcttc atggtggaca attagtttgt ttacagtgtt gcagtgaaca ttcttgtgca tacatctttg ctcctatatg caagtgtatc tataagatta atagacttta ttttttaaat taagagaaat gtctacttca tttgtcttat atcctagttc tcgttaggtg tgggatcaaa atgtgttacg ctagtagcta gcgcacatcc aggtttctct gcatgggtgt tgtgtgtcct gaatcttcag gtgtgctgct ggaacagctt gtggagcaca gctgggtatt cctcagagag ggtatagctt tagctcctta ttctacaaca agagagctgg ctattgtcaa tgacctcaag cttctgtttt aaaggcttaa tcttgttagg ctctctaaaa ttttgctttt tttctttttt attgagtaga aaacatttct caggttgcta agctggaata aaatccactt acctgtatgt taaatgattt ag SEQ ID NO: 4. Nucleic acid sequence encoding sgRNA for FECH M98K mutation GTGTCATGAGGTCTCGGTCCAGG SEQ ID NO: 5. ssODN donor DNA sequence for FECH M98K mutation TGGAGAAGTTCAAGACTTTCTTCAGAGGCTCTTTCTAGATCGTGACCTTAAGACACTTCC CATTCAAAAGTAAGT TAAGCTTTGTGGAGGGTCGTGTGTGG 37 ME146394007v.1 128748-02820 SEQ ID NO: 6. Fragment of human FECH intron 3 inserted into mouse FECH for IVS/KO mouse model. The IVS-48T/C mutation (T1658C) is shown in bold and underlined CTGGCTATTGTCAATGACCTCAAGCTTCTGTTTTAAAGGCTTAATCTTGTTAGGCTCTCT AAAATTTTGCTTTTT ^{TTCTTTTTTATTGAGTAGAAAACATTTCTCAGGCTGCTAAGCTGGAATAAAATCC ACTTACCTGTATGTTAAATG} ATTTAG SEQ ID NO: 7. Fragment of the mouse FECH genomic DNA sequence showing exon 3, intron 3, and exon 4 (from NCBI Reference Sequence: NC_000084.7) Exons 3 and 4 are underlined. The nucleotides that are replaced with the human FECH intron 3 fragment to generate the IVS/KO mouse model are shown in bold. 10321 ttgtgtagga agccaaaaac gggcatattg atgttaaaca tgggaggccc cgaaaccctt 10381 ggagaagttc aagactttct tcagaggctc ttcctggacc gagacctcat gacacttccc 10441 attcaaaagt aagttatgct gtgtggaggg tcgtgtgtgg ggtgcgtttg tcatctgtgc 10501 ggctctggcc gtggtcacgg cagcacctgt gtcttctgta gggaagcaga gggaaatggt 10561 atgcagagcc ctacagcagg agagccagtt agccagcact ctccttgggc cctctcctcc 10621 caggccctgg gagttacagc tgtctaagca tggctaaagt aactttaaag tgttgcagat 10681 ttgtaaagat gtatttgtga tgattaacat tgaagaagca atggttatca tttcctgtac 10741 ttgagggtgg actatggctt ttctctcctc ctttctattc ttacttcctt gcttcctttt 1 ^{0801 ctgccatttc ctttcaaaag acattttgca ataaagaaat gaactcgtgt atatccctgt} 10861 gactatgcaa atgatacgtt tacactaaaa agcaaatgtc cctttcacct cactggagtt 10921 ccagcaccag ttaaccaaag ggtattcctg ttttatttga aataacgtat gcataccgga 10981 gcctgtatat tcttccctct tcgtgataca aacgggaata cttgcctacc ttatttgtcg 11041 cttttgtggg gtttttcata atagtgtctg tttcataaca gattatatag atctgtcaaa 11101 tttcctcgtg acggttttga ttacatcttt atttagcttg cacctcattg gcagacagct 11161 atttacagtg tggctgtaga ccctgtattg tgtacctcac tgcccaccta cgcagcctta 11221 caggattagc attcattttg ctaaattaat agcagtgtgg actatggagg gggctcagag 11281 tttagttctt agaacccaca tccttgtttg tttgtttgtt tgtttgtttg tggctgtaat 11341 ctcagcactg gggaggaagt gctgtagggc aagctgaccc tccagccttg cttgctcagt 11401 aagttccagg tcagggagaa accctgtctg gtttttgttg ttgttgttgt tgttgttttg 11461 ttttgttttg ttttaaggtg gttatgcaga gaaaaatgtt caaggtcttt ttctggtcta 11521 tatgtacaca caggtaagca cacacagccc ttcactctgc acctgaatat atccgtgctt 11581 ccttacacac acaggcatac tttgttgttt ggtttggttt ggtttggttt ggttttgggt 11641 tgtttgtttg gttgtttgtt tgggtttttt ttggctttta gagacaaagt ttctctatgt 11701 agccttgttt gtttgtttgt ttggttgggt tttttttggc ttttagagac aaagtttctc 11761 tatgtagcct tggcagtcct agaaccccct ctgtagacca ggctggcctt aaacttatag 11821 agagctacct gcctctgcct tctgagtact gggattaaag gagagtacca ccccggccca 11881 accccagaca cccgtattaa gagtggcatc tgacactgag agagagtaga gccctggtca 11941 ggaagaggtt cttctgaaag tgatttcagc ttcgggtccg taggcttgtt ttgttcgttg 12001 gcttattagt cagatcacag gaatctcctc ccttcgtctg aattctcttg tcttagaaat 12061 tattaacccc gttgccagaa acagtcggta ccgtccactt tgctgactgt ttgctgatgt 12121 gccagaatgc ccctgatgcc gctgagctga ctcggcgtcc aggaaggcag gatgtgtggt 12181 gttcacacct ttgtggagtc atcccacagc atctcgcgca gccatagcat cccagttaac 12241 ttctgtctag ggttaaatag aggaaatggc aggttacaca gtgttctaaa ggcgctttga 12301 gagtcaggaa ggcgctatct ttggtacgat tatagataaa cttgccttgg ccttagcaca 12361 gggtgtacct gggtgttcat ataaagaaat acattatttt gtgcaatagt gaccatttta 12421 tttttggtta tttatttatt tatttatttg cttttttttt tttttttttt tttttttttt 12481 taagttcggt ggtggtgtct cacactttta gtcccagtag ggggatctct gtgagtttga 12541 gaccagcata gtctgcagac tgagttctgg gactgctaga gctacacaga gaaagcaacc 12601 ctgtttcaaa aacaaacaaa caaacaaaca aacaaaccaa accaaccttt gtattgtaaa 12661 ttgtgtgtgt gtgcatgtgt gggtacagga gctgaggaat ctaaaggagg gtgtcagagc 12721 ccttggaacg gaagctgcag gtgattgtga gctgccggcc gtgggtgctg ggagcagagc 12781 tggagacttc tgcccgagca gcacgtgctc tcagctgcta agccatcttt ccagtcccaa 12841 agcgaggttt tgatgcccaa gaattttgat attttaattg ctgaggcctc tgttcgatgc 12901 agtgctttct aatctcttaa gtccagttct gtcgcgcgct gagagatggg ctgtgtaatg 12961 tgtcctttca gtggtagttg ttttagaaac taaaagctac ttattatctt ctagagaaat 13021 ttcttaacat tgcactcaat atttataatt gcatcagaaa gtcttggttg aaacttaagc 13081 ttgatgtgac tccaccaaaa cctgttttgt tacaccaaag gataaatttc tttttatatt 38 ME146394007v.1 128748-02820 13141 ttactgtgtg tgtgtgtgtg tgtgtgtgtg tgtgtgtaca tcatggaggg actcgcatgg 13201 tgggagagaa ccaactcaac tcatgtaaat tgtcctctgt ccaccacatt tttaccagag 13261 tgtatacaca tgtgtgcacg tacacacaca cacacacaca cacacacaca cactaataat 13321 agtaaatgta acaaaaatgc ttttaaaaga gccctatgtg agttaggctt ggtgaagcga 1 ^{3381 gaggctgagg aaatagtcca cagggccagc ctgagcagca ttgtagttca agggctgtcc} 13441 aagaaacatg gtgagattct gtctcaaaat taaaaacaaa cggggccaat cctggggcct 13501 cagctcaatg gcagagtctt tgcctagcac cacgagggcc cagcttcagg ctcacagaac 13561 caaacaccac cgacaaaacc agtgcaggct ttctgtgctt tctcccctga ttcttgttag 13621 gtgcagattc agcacgtagg atggtagcta tcagcatccc agtcctgggt gtgaggtctc 1 ^{3681 cagagtgtgc aggatagagc acgtgtggag tgcaggggtg agctctcaga tccatgctga} 13741 attgtcaggc gcctctcggc cacattcctg accgctggtc ctgtttggct ctccttagga 13801 agttttactc atctcttcta tagtgaatag gaaatgtact tggagtttcg aaggtggaat 13861 aaaatccact cacttatgtg tccaatgatt tagtaagctg gcaccattca tcgccaaacg 13921 ccgaaccccc aaaattcaag agcagtatcg cagaatcgga ggtggatccc ccatcaagat 13981 gtggacttcc aagcaaggag aaggcatggt gaagctgctg gatgagttat cccctgccac 14041 aggtgtgctc ttcttcttag tgctgggcta ggctcgttac agtaggactc agggtcaggg SEQ ID NO: 8. ssDNA sequences used to insert the 156 bp fragment of human FECH gene intron 3 into the mouse genome for production of the IVS/KO mouse model. The human FECH intron 3 sequence is capitalized with the IVS-48T/C mutation (T1658C) shown in bold and underlined. cggggccaatcctggggcctcagctcaatggcagagtctttgcctagcaccacgagggcc cagcttcaggctcac agaaccaaacaccaccgacaaaaccagtgcaggctttctgtgctttctcccctgattctt gttaggtgcagattc agcacgtaggatggtagctatcagcatcccagtcctgggtgtgaggtctccagagtgtgc aggatagagcacgtg tggagtgcaggggtgagctctcagatccatgcCTGGCTATTGTCAATGACCTCAAGCTTC TGTTTTAAAGGCTTA ATCTTGTTAGGCTCTCTAAAATTTTGCTTTTTTTCTTTTTTATTGAGTAGAAAACATTTC TCAGGCTGCTAAGCT GGAATAAAATCCACTTACCTGTATGTTAAATGATTTAGtaagctggcaccattcatcgcc aaacgccgaaccccc ^{aaaattcaagagcagtatcgcagaatcggaggtggatcccccatcaagatgtgga cttccaagcaaggagaaggc} 61 gcagcagcta tgttgctacg gtcctgtcca gtgctctctc agggccccac aggcctcctg 121 ggcaaagtgg ctaaaaccta ccagttccta tttagtattg gacgctgccc catcctggcc 181 actcaaggac caacctgttc tcaaatccat cttaaggcaa ccaaggctgg aggagaactc 241 caagacagga agagcaagat tgtgcagagg gcagctccag aagttcaaga ggatgtcaag 301 actttcaaga cagacctgct gagcaccatg gattcaacca cccgaagcca ttcatttcct 361 agtttccagg agccagagca gactgaaggg gcagttcccc acctgattca gaacaatatg 421 actggaagcc aggctttcgg ttatgaccaa tttttcagag acaagatcat ggagaagaaa 481 caggaccaca cctaccgtgt gttcaagact gtgaatcgtt gggctaatgc ctaccccttt 541 gcccaacact tctccgaggc atctatggca tcaaaggatg tttctgtttg gtgtagtaat 601 gactatttgg gcataagcag acaccctcgt gtcttgcagg ccatagagga gaccctgaag 661 aatcatggag ctggagctgg gggcactcgc aatatctcag gtaccagcaa gtttcatgtg 721 gagcttgaac aggagctggc tgaactacac cagaaagact cagctctgct cttctcctcc 781 tgttttgtgg ccaatgattc tactctcttt acactggcca agcttctgcc agggtgtgag 841 atctactcag atgcaggcaa tcatgcctcc atgatccaag gcattcgcaa cagtggtgca 901 gccaagtttg tcttcagaca caatgaccca ggccacctga agaaacttct cgagaagtct 961 gatcccaaga caccaaaaat tgtggctttt gagactgttc attccatgga tggtgccatc 1021 tgtcctctgg aggaattgtg tgatgtggcc caccagtatg gagccctgac cttcgtagat 1081 gaagtccatg ctgtaggact gtatggagcc cggggtgcag gtatcgggga gcgtgatgga 1141 attatgcaca agcttgacat catctctgga actcttggca aggcctttgg ttgcgtcggt 1201 ggctatatag ccagcactcg ggacttggtg gacatggtgc gctcctacgc tgcaggcttc 1 ^{261 atctttacca cttcactgcc tcccatggtg ctctctgggg ctctagaatc tgtgcgccta} 1321 ctcaagggag aggagggtca agccctgagg cgggcacacc agcgcaatgt caaacacatg 39 ME146394007v.1 128748-02820 1381 cgccagctgc taatggacag gggctttcct gttatcccct gtcccagcca catcatcccc 1441 atcagggtgg gtaatgcagc actcaacagc aagatctgtg atcttctgct ctccaagcac 1501 agcatctatg tgcaggccat caactaccca actgtgcctc gtggtgagga gctactgcgc 1561 ttggccccct ccccccacca cagccctcag atgatggaaa actttgtgga gaagctgctg 1 ^{621 ctggcctgga ctgaggtggg gctgcccctc caagatgtgt ctgtggctgc atgcaacttc} 1681 tgtcatcgtc ctgtgcactt tgaacttatg agcgagtggg agcgatccta ctttgggaac 1741 atgggacccc aatatgttac cacctatgct taaggagcca gctgccttgg atgccagctc 1801 cacctgcact ccccctgggg ctgggcttcc tcctgctctc tgctttcctg tgtgcttctg 1861 gctgacttga ttctgaaaat aaagagcaac ttgaaacatt SEQ ID NO: 10. Amino acid sequence of mutated human ALAS2 fragment inserted into mouse ALAS2 gene for delAGTG mouse model GNVPTSGTWGPSMSPPMPEKPAA* SEQ ID NO: 11. 71 bp nucleic acid sequence inserted into mouse ALAS2 gene for delAGTG mouse model. Encodes SEQ ID NO: 10 when combined with guanosine resiude in mouse ALAS2 gene directly upstream of insertion site. ggaacgttcctacttcgggtacctggggccccagtatgtcaccacctatgcctgagaagc cagctgcctag SEQ ID NO: 12. Nucleic acid sequence encoding sgRNA used to prepare delAGTG mouse model ATGCTTAAGGAGCCAGCTGC SEQ ID NO: 13. Nucleic acid sequence encoding sgRNA used to prepare delAGTG mouse model CAATATGTTACCACCTATGC ^{SEQ ID NO: 14. Nucleic acid sequence encoding sgRNA used to prepare FECH} M98K mouse be model GTGTCATGAGGTCTCGGTCCAGG SEQ ID NO: 15. ssODN donor DNA sequence used to generate FECH M98K mouse model TGGAGAAGTTCAAGACTTTCTTCAGAGGCTCTTTCTAGATCGTGACCTTAAGACACTTCC CATTCAAAAGTAAGT TAAGCTTTGTGGAGGGTCGTGTGTGG SEQ ID NO: 16. shALAS2 RNA sequence UGAAAAAUUGGUCAUAACCGAA SEQ ID NO: 17. shRNA targeting FECH for in vitro model GCTTTGCAGATCATATTCTAA SEQ ID NO: 18. shRNA targeting UROS for in vitro model TCAGTGTATGTGGTTGGAAAT SEQ ID NO: 19. Nucleic acid sequence encoding gRNA used to generate delAGTG mouse model 40 ME146394007v.1 128748-02820 ATGCTTAAGGAGCCAGCTGC SEQ ID NO: 20. Nucleic acid sequence encoding gRNA used to generate delAGTG mouse model CAATATGTTACCACCTATGC SEQ ID NO: 21. Nucleic acid sequence encoding gRNA used to introduce the fragment of intron 3 of the human FECH gene into the mouse FECH genomic locus in the FECH-IVS/KO mouse model ^{AGGCGCCTGACAATTCAGCA} SEQ ID NO: 22. Nucleic acid sequence encoding gRNA used to introduce the fragment of intron 3 of the human FECH gene into the mouse FECH genomic locus in the FECH-IVS/KO mouse model TCATTGGACACATAAGTGAG SEQ ID NO: 23. Nucleic acid sequence encoding gRNA used to knockout mouse FECH gene in the FECH-IVS/KO mouse model ^{GAACTTCTCCAAGGGTTTCG} SEQ ID NO: 24. Fragment of human ALAS2 gene, exon 11 TAVGLPLQDV SVAACNFCRR PVHFELMSEW ERSYFGNMGPQYVTTYA SEQ ID NO: 25. Fragment of human ALAS2 gene, exon 11, after delAGTG mutation TAVGLPLQDV SVAACNFCRR PVHFELMSGN VPTSGTWGPSMSPPMPEKPA A SEQ ID NO: 26. gpFech-fw1-BglII PCR primer ataagatctGAAAGCCAGACCTGCGTACT ^{SEQ ID NO: 27. gpFech-rev2-EcoR1 PCR primer} tatgaattcCTGGCTAACTGGCTCTCCTG SEQ ID NO: 28. sgRNA-IVS-sg forward primer ttaatacgactcactataggAGGCGCCTGACAATTCAGCAgttttagagctagaaatag SEQ ID NO: 29. sgRNA-IVS-sg reverse primer aaaagcaccgactcggtgccac SEQ ID NO: 30. RA-sg#1 forward primer ttaatacgactcactataggTCATTGGACACATAAGTGAGgttttagagctagaaatag SEQ ID NO: 31. ex2-F-S primer 41 ME146394007v.1 128748-02820 GGAGAAGGTACATCATGCCAAGAC SEQ ID NO: 32. ex4-R-S primer CTGTGGCAGGGGATAACTC SEQ ID NO: 33. Ex3-F primer CCTCATGACACTTCCCATTCAA SEQ ID NO: 34. Forward primer to generate sgRNA template for Mouse FECH KO mutation ttaatacgactcactataggGAACTTCTCCAAGGGTTTCGgttttagagctagaaatag SEQ ID NO: 35. CC25 primer AAACCAGTCACACACCTGAAGTGC SEQ ID NO: 36. CC26 primer GGCTAGACTTGTCTGAGTGAGTGAG SEQ ID NO: 37. sdRNA targeting ALAS2 CGUCUGGUGUAGUAAUGAUU SEQ ID NO: 38. Mus musculus sequence from Figure 2 CRRPVHFELMS SEQ ID NO: 39. Fragment of mouse FECH gene containing M98K mutation in Figure 4 tttctagatcgtgaccttaagacacttcccattcaa SEQ ID NO: 40. Fragment of mouse FECH protein containing M98K mutation in Figure 4 FLDRDLKTLPIQ SEQ ID NO: 41. mouse FECH knockout mutant, Figure 14A aacgggcatattgatgttaaacatgggaggccccttggagaag SEQ ID NO: 42. mouse FECH knockout mutant, Figure 14B MLSASANMAAALRAAGALLREPLVHGSSRACQPWRCQSGAAVAATTEKVHHAKTTKPQAQ PERRKPKT GILMLNMGGPLEKFKTFFRGSSWTETS 42 ME146394007v.1