|A service of the U.S. National Library of Medicine®|
On this page:
Reviewed July 2011
What is the official name of the MMADHC gene?
The official name of this gene is “methylmalonic aciduria (cobalamin deficiency) cblD type, with homocystinuria.”
MMADHC is the gene's official symbol. The MMADHC gene is also known by other names, listed below.
Read more about gene names and symbols on the About page.
What is the normal function of the MMADHC gene?
The MMADHC gene provides instructions for making a protein that helps convert vitamin B12 (also called cobalamin) into one of two molecules, adenosylcobalamin (AdoCbl) or methylcobalamin (MeCbl). AdoCbl is required for the normal function of an enzyme known as methylmalonyl CoA mutase. This enzyme helps break down certain protein building blocks (amino acids), fats (lipids), and cholesterol. AdoCbl is called a cofactor because it helps methylmalonyl CoA mutase carry out its function. MeCbl is also a cofactor, but for an enzyme known as methionine synthase. This enzyme converts the amino acid homocysteine to another amino acid, methionine. The body uses methionine to make proteins and other important compounds.
Research indicates that the MMADHC protein may play a role in one of the last steps in AdoCbl and MeCbl formation, the transport of vitamin B12 into mitochondria (specialized structures inside cells that serve as energy-producing centers). Additional chemical reactions then convert vitamin B12 into AdoCbl or MeCbl.
How are changes in the MMADHC gene related to health conditions?
Where is the MMADHC gene located?
Cytogenetic Location: 2q23.2
Molecular Location on chromosome 2: base pairs 149,569,633 to 149,587,816
(Homo sapiens Annotation Release 107, GRCh38.p2) (
The MMADHC gene is located on the long (q) arm of chromosome 2 at position 23.2.
More precisely, the MMADHC gene is located from base pair 149,569,633 to base pair 149,587,816 on chromosome 2.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about MMADHC?
You and your healthcare professional may find the following resources about MMADHC helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
What other names do people use for the MMADHC gene or gene products?
See How are genetic conditions and genes named? in the Handbook.
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding MMADHC?
acids ; aciduria ; amino acid ; cholesterol ; CoA ; cobalamin ; cofactor ; deficiency ; depleted ; developmental delay ; disability ; enzyme ; gene ; methionine ; mitochondria ; neurological ; precursor ; protein ; toxic ; vitamin B12
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (5 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.