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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed July 2011

What is the official name of the MCEE gene?

The official name of this gene is “methylmalonyl-CoA epimerase.”

MCEE is the gene's official symbol. The MCEE gene is also known by other names, listed below.

What is the normal function of the MCEE gene?

The MCEE gene provides instructions for making an enzyme called methylmalonyl CoA epimerase, which converts one form of the molecule methylmalonyl CoA to another. Specifically, the enzyme converts D-methylmalonyl CoA to L-methylmalonyl CoA. This conversion takes place within the pathway that converts the molecule propionyl-CoA to succinyl-CoA. This pathway is important in the breakdown of certain protein building blocks (amino acids), specific fats (lipids), and cholesterol.

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

methylmalonic acidemia - caused by mutations in the MCEE gene

At least three mutations in the MCEE gene have been found to cause methylmalonic acidemia, a condition characterized by feeding difficulties, developmental delay, and long-term health problems. These mutations are thought to result in the production of a methylmalonyl CoA epimerase enzyme with little or no function. People with methylmalonic acidemia caused by mutations in the MCEE gene typically have milder signs and symptoms than people with the condition caused by mutations in other genes. The features may be milder because there is an alternate pathway for the conversion of propionyl-CoA to succinyl-CoA that does not involve methylmalonyl CoA epimerase, so some succinyl-Co is produced even when there are mutations in the MCEE gene. This alternate pathway cannot compensate for the breakdown of certain molecules that occurs in the regular pathway, so people with MCEE gene mutations still have a buildup of the byproducts of some amino acids and certain fats. As a result, these toxic compounds build up in the body's organs and tissues, causing the signs and symptoms of methylmalonic acidemia.

Where is the MCEE gene located?

Cytogenetic Location: 2p13.3

Molecular Location on chromosome 2: base pairs 71,109,676 to 71,130,288

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The MCEE gene is located on the short (p) arm of chromosome 2 at position 13.3.

The MCEE gene is located on the short (p) arm of chromosome 2 at position 13.3.

More precisely, the MCEE gene is located from base pair 71,109,676 to base pair 71,130,288 on chromosome 2.

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

Where can I find additional information about MCEE?

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

  • DL-methylmalonyl-CoA racemase
  • GLOD2
  • glyoxalase domain containing 2
  • methylmalonyl CoA epimerase
  • methylmalonyl-CoA epimerase, mitochondrial
  • methylmalonyl-CoA epimerase, mitochondrial precursor

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding MCEE?

acids ; breakdown ; cholesterol ; CoA ; developmental delay ; domain ; enzyme ; gene ; molecule ; precursor ; protein ; toxic

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Bikker H, Bakker HD, Abeling NG, Poll-The BT, Kleijer WJ, Rosenblatt DS, Waterham HR, Wanders RJ, Duran M. A homozygous nonsense mutation in the methylmalonyl-CoA epimerase gene (MCEE) results in mild methylmalonic aciduria. Hum Mutat. 2006 Jul;27(7):640-3. (
  • Dobson CM, Gradinger A, Longo N, Wu X, Leclerc D, Lerner-Ellis J, Lemieux M, Belair C, Watkins D, Rosenblatt DS, Gravel RA. Homozygous nonsense mutation in the MCEE gene and siRNA suppression of methylmalonyl-CoA epimerase expression: a novel cause of mild methylmalonic aciduria. Mol Genet Metab. 2006 Aug;88(4):327-33. Epub 2006 May 11. (
  • Gradinger AB, Bélair C, Worgan LC, Li CD, Lavallée J, Roquis D, Watkins D, Rosenblatt DS. Atypical methylmalonic aciduria: frequency of mutations in the methylmalonyl CoA epimerase gene (MCEE). Hum Mutat. 2007 Oct;28(10):1045. (
  • NCBI Gene (


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: February 8, 2016