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Gene

MMADHC

metabolism of cobalamin associated D

Summary

Cytogenetic location
2q23.2
Coordinates
Chromosome 2: 149,569,637–149,587,775 (GRCh38)
Exons
8 exons across 18.1 kb
Protein
296 amino acids
Inheritance
Autosomal recessive
Also known as
CL25022, cblD
Previous symbols
C2orf25
MANE Select transcript
ENST00000303319.10NM_015702.3
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.

      • 3 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
      • 6 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.

      • 3 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 MMADHC is laid out

  • Coding sequence
  • Untranslated region
  • Intron
  • Direction of transcription
  • Known disease-causing sites
  • Stretches short reads find hard
Chromosome 2, with a bracket where MMADHC sits. MMADHC and 2 genes near it on chromosome 2, from 149,078,706 to 150,078,705.Chromosome 22q23.2p25.3p25.2p25.1p24.3p24.2p24.1p23.3p23.2p23.1p22.3p22.2p22.1p21p16.3p16.2p16.1p15p14p13.3p13.2p13.1p12p11.2p11.1q11.1q11.2q12.1q12.2q12.3q13q14.1q14.2q14.3q21.1q21.2q21.3q22.1q22.2q22.3q23.1q23.2q23.3q24.1q24.2q24.3q31.1q31.2q31.3q32.1q32.2q32.3q33.1q33.2q33.3q34q35q36.1q36.2q36.3q37.1q37.2q37.3149.2 Mb149.4 Mb149.6 Mb149.8 Mb150 MbLYPD6B: 149,037,975–149,215,266, forward strandLYPD6BLYPD6: 149,329,985–149,474,139, forward strandLYPD6MMADHC: 149,569,637–149,587,775, reverse strandMMADHCDiagram of MMADHC: 8 exons on the reverse strand of chromosome 2Exon 8: 6 known disease-causing sitesExon 7: 8 known disease-causing sitesExon 6: 11 known disease-causing sitesExon 5: 6 known disease-causing sitesExon 4: 11 known disease-causing sitesExon 3: 7 known disease-causing sitesExon 8: 149,569,637–149,570,168, 532 basesExon 7: 149,571,085–149,571,171, 87 basesExon 6: 149,575,711–149,575,841, 131 basesExon 5: 149,576,437–149,576,542, 106 basesExon 4: 149,579,431–149,579,648, 218 basesExon 3: 149,582,127–149,582,271, 145 basesExon 2: 149,587,089–149,587,149, 61 basesExon 1: 149,587,664–149,587,775, 112 bases876543215′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 1.4 kb of the gene's 18.1 kb; 891 of those bases code for the protein.

How a genome test reads MMADHC

63

positions in MMADHC 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 18.1 kb of MMADHC, introns included, not only the 1.4 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.). MMADHC gene: metabolism of cobalamin associated D. Retrieved 16 October 2026, from https://dantelabs.com/genes/mmadhc

Vancouver

Dante Labs. MMADHC gene: metabolism of cobalamin associated D [Internet]. [cited 16 October 2026]. Available from: https://dantelabs.com/genes/mmadhc

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