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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 2007

What is the official name of the PCCB gene?

The official name of this gene is “propionyl CoA carboxylase, beta polypeptide.”

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

What is the normal function of the PCCB gene?

The PCCB gene provides instructions for making part of an enzyme called propionyl-CoA carboxylase, specifically, the beta subunit of this enzyme. Six beta subunits come together with six alpha subunits (produced from the PCCA gene) to form a functioning enzyme.

Propionyl-CoA carboxylase plays a role in the normal processing of proteins. It is responsible for a particular step in the breakdown of several protein building blocks (amino acids) called isoleucine, methionine, threonine, and valine. Propionyl-CoA carboxylase also helps break down certain types of lipids (fats) and cholesterol. First, several chemical reactions convert the amino acids, lipids, or cholesterol to a molecule called propionyl-CoA. Using the B vitamin biotin, propionyl-CoA carboxylase then converts propionyl-CoA to a molecule called methylmalonyl-CoA. Additional enzymes break down methylmalonyl-CoA into other molecules that are used for energy.

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

propionic acidemia - caused by mutations in the PCCB gene

More than 55 mutations in the PCCB gene have been identified in people with propionic acidemia. These mutations include changes in single DNA building blocks (nucleotides) and insertions or deletions of genetic material in the PCCB gene. PCCB mutations prevent the production of functional propionyl-CoA carboxylase or reduce the enzyme's activity. The altered or missing enzyme prevents certain parts of proteins and lipids from being broken down properly. As a result, propionyl-CoA and other potentially toxic compounds can build up to toxic levels in the body. This buildup damages the brain and nervous system, causing the serious health problems associated with propionic acidemia.

Where is the PCCB gene located?

Cytogenetic Location: 3q21-q22

Molecular Location on chromosome 3: base pairs 136,250,324 to 136,332,588

The PCCB gene is located on the long (q) arm of chromosome 3 between positions 21 and 22.

The PCCB gene is located on the long (q) arm of chromosome 3 between positions 21 and 22.

More precisely, the PCCB gene is located from base pair 136,250,324 to base pair 136,332,588 on chromosome 3.

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

Where can I find additional information about PCCB?

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

  • PCCase beta subunit
  • propanoyl-CoA:carbon dioxide ligase beta subunit
  • propionyl-CoA carboxylase, beta subunit

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

What glossary definitions help with understanding PCCB?

acids ; biotin ; breakdown ; carboxylase ; cholesterol ; CoA ; DNA ; enzyme ; gene ; isoleucine ; ligase ; methionine ; molecule ; nervous system ; protein ; subunit ; threonine ; toxic ; valine

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


  • Desviat LR, Clavero S, Perez-Cerdá C, Navarrete R, Ugarte M, Perez B. New splicing mutations in propionic acidemia. J Hum Genet. 2006;51(11):992-7. Epub 2006 Oct 19. (
  • Desviat LR, Pérez B, Pérez-Cerdá C, Rodríguez-Pombo P, Clavero S, Ugarte M. Propionic acidemia: mutation update and functional and structural effects of the variant alleles. Mol Genet Metab. 2004 Sep-Oct;83(1-2):28-37. Review. (
  • NCBI Gene (
  • Pérez B, Desviat LR, Rodríguez-Pombo P, Clavero S, Navarrete R, Perez-Cerdá C, Ugarte M. Propionic acidemia: identification of twenty-four novel mutations in Europe and North America. Mol Genet Metab. 2003 Jan;78(1):59-67. (
  • Pérez-Cerdá C, Clavero S, Pérez B, Rodríguez-Pombo P, Desviat LR, Ugarte M. Functional analysis of PCCB mutations causing propionic acidemia based on expression studies in deficient human skin fibroblasts. Biochim Biophys Acta. 2003 May 20;1638(1):43-9. (


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 2007
Published: March 2, 2015