Skip Navigation
Genetics Home Reference: your guide to understanding genetic conditions About   Site Map   Contact Us
 
Home A service of the U.S. National Library of Medicine®
 
 
Printer-friendly version
MMAA

MMAA

Reviewed July 2011

What is the official name of the MMAA gene?

The official name of this gene is “methylmalonic aciduria (cobalamin deficiency) cblA type.”

MMAA is the gene's official symbol. The MMAA 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 MMAA gene?

The MMAA gene provides instructions for making a protein that is involved in the formation of a compound called adenosylcobalamin (AdoCbl). AdoCbl, which is derived from vitamin B12 (also called cobalamin), is necessary for the normal function of an enzyme known as methylmalonyl CoA mutase. This enzyme helps break down certain proteins, fats (lipids), and cholesterol.

Research indicates that the MMAA protein may play a role in one of the last steps in AdoCbl 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. Other studies suggest that the MMAA protein may help stabilize methylmalonyl CoA mutase and protect the enzyme from being turned off (inactivated).

How are changes in the MMAA gene related to health conditions?

methylmalonic acidemia - caused by mutations in the MMAA gene

More than 25 mutations in the MMAA gene have been found to cause methylmalonic acidemia, a condition characterized by feeding difficulties, developmental delay, and long term health problems. Some of these mutations add, delete, or duplicate a small amount of genetic material in the gene. Other mutations change a single protein building block (amino acid) used to make the MMAA protein. These mutations can lead to the production of an unstable MMAA protein or an abnormally small, nonfunctional version of the protein. It is unclear how the abnormal MMAA protein leads to the serious medical problems associated with methylmalonic acidemia. Studies suggest that without the activity of this protein, AdoCbl may not be made properly. A lack of AdoCbl impairs the function of methylmalonyl CoA mutase, which results in the incomplete break down of certain proteins and lipids. This defect allows toxic compounds to build up in the body's organs and tissues. Research suggests that a lack of AdoCbl leading to impaired methylmalonyl CoA mutase function causes the signs and symptoms of methylmalonic acidemia.

Where is the MMAA gene located?

Cytogenetic Location: 4q31.21

Molecular Location on chromosome 4: base pairs 145,619,387 to 145,660,034

The MMAA gene is located on the long (q) arm of chromosome 4 at position 31.21.

The MMAA gene is located on the long (q) arm of chromosome 4 at position 31.21.

More precisely, the MMAA gene is located from base pair 145,619,387 to base pair 145,660,034 on chromosome 4.

See How do geneticists indicate the location of a gene? in the Handbook.

Where can I find additional information about MMAA?

You and your healthcare professional may find the following resources about MMAA 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 MMAA gene or gene products?

  • cblA
  • methylmalonic aciduria (cobalamin deficiency) type A
  • methylmalonic aciduria type A
  • MMAA_HUMAN

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 MMAA?

aciduria ; amino acid ; cholesterol ; CoA ; cobalamin ; cofactor ; compound ; deficiency ; developmental delay ; enzyme ; gene ; mitochondria ; 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 (9 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.

 
Reviewed: July 2011
Published: April 7, 2014