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


Reviewed November 2010

What is the official name of the SLC25A20 gene?

The official name of this gene is “solute carrier family 25 (carnitine/acylcarnitine translocase), member 20.”

SLC25A20 is the gene's official symbol. The SLC25A20 gene is also known by other names, listed below.

What is the normal function of the SLC25A20 gene?

The SLC25A20 gene provides instructions for making a protein called carnitine-acylcarnitine translocase (CACT). This protein is essential for fatty acid oxidation, a multistep process that breaks down (metabolizes) fats and converts them into energy. Fatty acid oxidation takes place within mitochondria, which are the energy-producing centers in cells. A group of fats called long-chain fatty acids must be attached to a substance known as carnitine to enter mitochondria. Once these fatty acids are joined with carnitine, the CACT protein transports them into mitochondria. Carnitine is then removed from the long-chain fatty acid and transported back out of mitochondria by the CACT protein. Fatty acids are a major source of energy for the heart and muscles. During periods of fasting, fatty acids are also an important energy source for the liver and other tissues.

Does the SLC25A20 gene share characteristics with other genes?

The SLC25A20 gene belongs to a family of genes called SLC (solute carriers).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? ( in the Handbook.

How are changes in the SLC25A20 gene related to health conditions?

carnitine-acylcarnitine translocase deficiency - caused by mutations in the SLC25A20 gene

At least 27 mutations in the SLC25A20 gene have been found to cause carnitine-acylcarnitine translocase (CACT) deficiency. Although these mutations change the structure of the CACT protein in different ways, they all lead to a shortage (deficiency) of the protein. Without enough functional CACT protein, long-chain fatty acids cannot be transported into mitochondria. As a result, these fatty acids are not converted to energy. Reduced energy production can lead to some of the features of CACT deficiency, such as low blood sugar (hypoglycemia) and low levels of the products of fat breakdown (hypoketosis). Fatty acids and long-chain acylcarnitines (fatty acids still attached to carnitine) may also build up in cells and damage the liver, heart, and muscles. This abnormal buildup causes the other signs and symptoms of the disorder.

Where is the SLC25A20 gene located?

Cytogenetic Location: 3p21.31

Molecular Location on chromosome 3: base pairs 48,856,923 to 48,898,993

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

The SLC25A20 gene is located on the short (p) arm of chromosome 3 at position 21.31.

The SLC25A20 gene is located on the short (p) arm of chromosome 3 at position 21.31.

More precisely, the SLC25A20 gene is located from base pair 48,856,923 to base pair 48,898,993 on chromosome 3.

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

Where can I find additional information about SLC25A20?

You and your healthcare professional may find the following resources about SLC25A20 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 SLC25A20 gene or gene products?

  • CAC
  • CACT
  • carnitine-acylcarnitine carrier
  • carnitine/acylcarnitine translocase

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

What glossary definitions help with understanding SLC25A20?

acids ; breakdown ; carnitine ; carrier ; deficiency ; fasting ; fatty acids ; gene ; hypoglycemia ; mitochondria ; oxidation ; protein ; solute

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


  • Costa C, Costa JM, Slama A, Boutron A, Vequaud C, Legrand A, Brivet M. Mutational spectrum and DNA-based prenatal diagnosis in carnitine-acylcarnitine translocase deficiency. Mol Genet Metab. 2003 Jan;78(1):68-73. (
  • Galron D, Birk OS, Kazanovitz A, Moses SW, Hershkovitz E. Carnitine-acylcarnitine translocase deficiency: identification of a novel molecular defect in a Bedouin patient. J Inherit Metab Dis. 2004;27(2):267-73. Review. (
  • Iacobazzi V, Invernizzi F, Baratta S, Pons R, Chung W, Garavaglia B, Dionisi-Vici C, Ribes A, Parini R, Huertas MD, Roldan S, Lauria G, Palmieri F, Taroni F. Molecular and functional analysis of SLC25A20 mutations causing carnitine-acylcarnitine translocase deficiency. Hum Mutat. 2004 Oct;24(4):312-20. (
  • Iacobazzi V, Pasquali M, Singh R, Matern D, Rinaldo P, Amat di San Filippo C, Palmieri F, Longo N. Response to therapy in carnitine/acylcarnitine translocase (CACT) deficiency due to a novel missense mutation. Am J Med Genet A. 2004 Apr 15;126A(2):150-5. (
  • Korman SH, Pitt JJ, Boneh A, Dweikat I, Zater M, Meiner V, Gutman A, Brivet M. A novel SLC25A20 splicing mutation in patients of different ethnic origin with neonatally lethal carnitine-acylcarnitine translocase (CACT) deficiency. Mol Genet Metab. 2006 Dec;89(4):332-8. Epub 2006 Aug 17. (
  • Longo N, Amat di San Filippo C, Pasquali M. Disorders of carnitine transport and the carnitine cycle. Am J Med Genet C Semin Med Genet. 2006 May 15;142C(2):77-85. Review. (
  • NCBI Gene (
  • Ramsay RR, Gandour RD, van der Leij FR. Molecular enzymology of carnitine transfer and transport. Biochim Biophys Acta. 2001 Mar 9;1546(1):21-43. Review. (
  • Rubio-Gozalbo ME, Bakker JA, Waterham HR, Wanders RJ. Carnitine-acylcarnitine translocase deficiency, clinical, biochemical and genetic aspects. Mol Aspects Med. 2004 Oct-Dec;25(5-6):521-32. Review. (


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: November 2010
Published: February 1, 2016