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Gene

ALAS2

5'-aminolevulinate synthase 2

Summary

Cytogenetic location
Xp11.21
Coordinates
Chromosome X: 55,009,055–55,030,977 (GRCh38)
Exons
11 exons across 21.9 kb
Protein
587 amino acids
Also known as
ALAS-E
Previous symbols
ASB
MANE Select transcript
ENST00000650242.1NM_000032.5
Locus type
gene with protein product
  • Very high
  • Confident
  • Low
  • Very low

Reference genomeGRCh38

Positions on gene and variant pages follow this choice, in this browser.

Curated reports relevant to this gene

  • Hepatic Porphyria Disorders

    • Hepatic Porphyria

      A group of metabolic diseases due to deficiency of one of a number of liver enzymes in the biosynthetic pathway of heme. They are characterized by the accumulation and increased excretion of porphyrins or its precursors. Clinical features include neurological symptoms (porphyria, acute intermittent), cutaneous lesions due to photosensitivity (porphyria cutanea tarda), or both (hereditary coproporphyria). Hepatic porphyrias can be hereditary or acquired as a result of toxicity to the hepatic tissues.

      • ClinGen rates the link definitive
      • 4 GenCC submitters rate it definitive or strong

  • Hereditary Sideroblastic Anaemias

    • Inherited Sideroblastic Anaemia

      A group of conditions caused by changes in genes such as ALAS2 and ABCB7 (X-linked), SLC25A38, GLRX5, PUS1, YARS2 and TRNT1 (recessive) and HSPA9 (dominant); some forms also affect the muscles, nervous system or immune system.

      • 3 GenCC submitters rate it definitive or strong
      What knowing changes

      The X-linked ALAS2 form often responds to vitamin B6 (pyridoxine), and a diagnosis guides iron-overload monitoring and distinguishes these conditions from acquired myelodysplastic syndrome.

  • Porphyria

    • Porphyria is a group of diseases in which substances called porphyrins build up, negatively affecting the skin or nervous system. Most types are inherited, but porphyria cutanea tarda may also be due to increased iron in the liver, hepatitis C, alcohol, or HIV/AIDS.

      • ClinGen rates the link definitive
      • 4 GenCC submitters rate it definitive or strong
      What knowing changes

      Attack prevention through trigger avoidance, IV dextrose or hemin during acute attacks, RNA interference therapy (givosiran), genetic counseling

How ALAS2 is laid out

  • Coding sequence
  • Untranslated region
  • Intron
  • Direction of transcription
  • Known disease-causing sites
  • Stretches short reads find hard
Chromosome X, with a bracket where ALAS2 sits. ALAS2 and 13 genes near it on chromosome X, from 54,520,016 to 55,520,015.Chromosome XXp11.21p22.33p22.32p22.31p22.2p22.13p22.12p22.11p21.3p21.2p21.1p11.4p11.3p11.23p11.22p11.21p11.1q11.1q11.2q12q13.1q13.2q13.3q21.1q21.2q21.31q21.32q21.33q22.1q22.2q22.3q23q24q25q26.1q26.2q26.3q27.1q27.2q27.3q2854.6 Mb54.8 Mb55 Mb55.2 Mb55.4 MbGNL3L: 54,529,900–54,621,565, forward strandGNL3LITIH6: 54,748,918–54,798,255, reverse strandITIH6MAGED2: 54,807,572–54,816,015, forward strandMAGED2TRO: 54,920,462–54,931,436, forward strandTROPFKFB1: 54,931,434–54,994,789, reverse strandPFKFB1APEX2: 55,000,323–55,009,057, forward strandAPEX2ALAS2: 55,009,055–55,030,977, reverse strandALAS2PAGE2B: 55,028,123–55,078,913, forward strandPAGE2BPAGE2: 55,089,011–55,092,842, forward strandPAGE2VCF2: 55,143,102–55,161,310, reverse strandVCF2PAGE5: 55,211,094–55,224,116, forward strandPAGE5PAGE3: 55,257,591–55,264,927, reverse strandPAGE3MAGEH1: 55,452,127–55,453,566, forward strandMAGEH1USP51: 55,484,616–55,489,874, reverse strandUSP51Diagram of ALAS2: 11 exons on the reverse strand of chromosome XExon 11: 1 known disease-causing siteExon 10: 1 known disease-causing siteExon 9: 2 known disease-causing sitesExon 8: 1 known disease-causing siteExon 6: 1 known disease-causing siteExon 5: 2 known disease-causing sitesExon 11: 55,009,055–55,009,343, 289 basesExon 10: 55,013,486–55,013,648, 163 basesExon 9: 55,014,747–55,015,015, 269 basesExon 8: 55,015,578–55,015,742, 165 basesExon 7: 55,017,486–55,017,665, 180 basesExon 6: 55,020,320–55,020,504, 185 basesExon 5: 55,021,052–55,021,274, 223 basesExon 4: 55,023,757–55,023,867, 111 basesExon 3: 55,024,718–55,024,840, 123 basesExon 2: 55,025,820–55,026,015, 196 basesExon 1: 55,030,942–55,030,977, 36 bases11109876543215′3′

Exons of the gene's MANE Select transcript (release v1.5), from NCBI and EMBL-EBI, on the GRCh38 reference genome.

Chromosome bands from UCSC's GRCh38 ideogram (2022-10-29).

Nearby genes from Ensembl release 116, on GRCh38.

Exons make up 1.9 kb of the gene's 21.9 kb; 1,764 of those bases code for the protein.

How a genome test reads ALAS2

11

positions in ALAS2 where ClinVar classes a change as pathogenic or likely pathogenic

None of them falls in a region short reads find hard.

A whole genome covers all 21.9 kb of ALAS2, introns included, not only the 1.9 kb of exons.

Where this comes from

  • HGNC: the gene's symbol, name, other symbols and location.
  • MANE Select v1.5, from NCBI and EMBL-EBI: the transcript, its exons and coding sequence.
  • GenCC and ClinGen, released 2026-10-16: which conditions the gene is linked to, and how strongly.
  • The ACMG secondary findings list, SF v3.2.
  • ClinVar and the GIAB stratifications: known disease-causing sites, and the regions short reads find hard.
  • The Human Phenotype Ontology, release 2026-09-01: the traits linked to the gene. Find out more at hpo.jax.org.
  • Data release 2026.10.16-c6eea6bf.

Cite this page

APA

Dante Labs. (n.d.). ALAS2 gene: 5'-aminolevulinate synthase 2. Retrieved 16 October 2026, from https://dantelabs.com/genes/alas2

Vancouver

Dante Labs. ALAS2 gene: 5'-aminolevulinate synthase 2 [Internet]. [cited 16 October 2026]. Available from: https://dantelabs.com/genes/alas2

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