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Gene

MMACHC

metabolism of cobalamin associated C

Summary

Cytogenetic location
1p34.1
Coordinates
Chromosome 1: 45,500,300–45,513,382 (GRCh38)
Exons
4 exons across 13.1 kb
Protein
282 amino acids
Inheritance
Autosomal recessive
Also known as
DKFZP564I122, cblC
MANE Select transcript
ENST00000401061.9NM_015506.3
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

  • Homocystinuria & Cobalamin Disorders

    • HomocystinuriaAutosomal recessive

      Includes classic homocystinuria due to CBS deficiency, severe MTHFR deficiency and the combined and remethylation cobalamin disorders, which can cause lens dislocation, blood clots, skeletal changes, anaemia and developmental problems.

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

      Knowing allows treatment with vitamin B6, B12, folate, betaine and diet as appropriate, which can prevent lens dislocation, thrombosis and other complications.

    • Inborn Disorders of Cobalamin Metabolism and TransportAutosomal recessive

      Includes defects in vitamin B12 absorption and transport such as Imerslund-Gräsbeck syndrome (CUBN, AMN), intrinsic factor deficiency (CBLIF) and transcobalamin II deficiency (TCN2), as well as intracellular cobalamin processing defects, which can cause megaloblastic anaemia, nerve damage and failure to thrive.

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

      Knowing allows lifelong vitamin B12 injections or other cobalamin treatment, which can prevent anaemia and neurological damage.

  • Methylmalonic & Propionic Acidemia

    • Methylmalonic AcidemiaAutosomal recessive

      Caused by variants in MMUT, MMAA, MMAB, MCEE and related cobalamin-processing genes, which can cause vomiting, poor feeding, metabolic crises, developmental problems and kidney disease.

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

      Knowing allows specialist dietary management, carnitine, vitamin B12 for responsive forms and an emergency plan, which reduces the risk of crises.

Inheritance

Autosomal recessive
It takes a changed copy from each parent. With one, you are a carrier and usually unaffected; when both parents are carriers, each child has a one-in-four chance of inheriting two.

How MMACHC is laid out

  • Coding sequence
  • Untranslated region
  • Intron
  • Direction of transcription
  • Known disease-causing sites
  • Stretches short reads find hard
Chromosome 1, with a bracket where MMACHC sits. MMACHC and 17 genes near it on chromosome 1, from 45,006,841 to 46,006,840.Chromosome 11p34.1p36.33p36.32p36.31p36.23p36.22p36.21p36.13p36.12p36.11p35.3p35.2p35.1p34.3p34.2p34.1p33p32.3p32.2p32.1p31.3p31.2p31.1p22.3p22.2p22.1p21.3p21.2p21.1p13.3p13.2p13.1p12p11.2p11.1q11q12q21.1q21.2q21.3q22q23.1q23.2q23.3q24.1q24.2q24.3q25.1q25.2q25.3q31.1q31.2q31.3q32.1q32.2q32.3q41q42.11q42.12q42.13q42.2q42.3q43q4445.2 Mb45.4 Mb45.6 Mb45.8 Mb46 MbHECTD3: 45,002,540–45,011,369, reverse strandHECTD3UROD: 45,010,950–45,015,577, forward strandURODZSWIM5: 45,016,395–45,306,209, reverse strandZSWIM5HPDL: 45,326,895–45,328,710, forward strandMUTYH: 45,329,163–45,340,893, reverse strandMUTYH: 45,329,262–45,491,155, reverse strandTOE1: 45,339,938–45,345,623, forward strandTOE1TESK2: 45,343,877–45,491,203, reverse strandTESK2CCDC163: 45,493,863–45,500,163, reverse strandCCDC163MMACHC: 45,500,300–45,513,382, forward strandMMACHCPRDX1: 45,510,914–45,542,816, reverse strandPRDX1AKR1A1: 45,550,475–45,570,051, forward strandAKR1A1NASP: 45,583,576–45,618,905, forward strandNASPCCDC17: 45,620,044–45,624,062, reverse strandCCDC17GPBP1L1: 45,627,284–45,688,408, reverse strandGPBP1L1TMEM69: 45,688,149–45,718,150, forward strandTMEM69KLHL27: 45,692,370–45,750,805, reverse strandKLHL27MAST2: 45,786,987–46,036,228, forward strandMAST2Diagram of MMACHC: 4 exons on the forward strand of chromosome 1Exon 1: 13 known disease-causing sitesExon 2: 25 known disease-causing sitesExon 3: 24 known disease-causing sitesExon 4: 67 known disease-causing sitesExon 1: 45,500,300–45,500,413, 114 basesExon 2: 45,507,356–45,507,550, 195 basesExon 3: 45,508,212–45,508,364, 153 basesExon 4: 45,508,796–45,513,382, 4,587 bases12345′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 5 kb of the gene's 13.1 kb; 849 of those bases code for the protein.

How a genome test reads MMACHC

144

positions in MMACHC 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 13.1 kb of MMACHC, introns included, not only the 5 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.). MMACHC gene: metabolism of cobalamin associated C. Retrieved 17 October 2026, from https://dantelabs.com/genes/mmachc

Vancouver

Dante Labs. MMACHC gene: metabolism of cobalamin associated C [Internet]. [cited 17 October 2026]. Available from: https://dantelabs.com/genes/mmachc

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