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SLC25A20 gene

solute carrier family 25 member 20

Normal Function

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.

Health Conditions Related to Genetic Changes

Carnitine-acylcarnitine translocase deficiency

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 glucose (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.

More About This Health Condition

Other Names for This Gene

  • CAC
  • CACT
  • carnitine-acylcarnitine carrier
  • carnitine/acylcarnitine translocase
  • solute carrier family 25 (carnitine/acylcarnitine translocase), member 20

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Gene and Variant Databases


  • 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. doi: 10.1016/s1096-7192(02)00205-6. Citation on PubMed
  • 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. doi: 10.1023/B:BOLI.0000028780.01670.61. Citation on PubMed
  • 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. doi: 10.1002/humu.20085. Citation on PubMed
  • 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. doi: 10.1002/ajmg.a.20573. Citation on PubMed
  • 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. doi: 10.1016/j.ymgme.2006.06.009. Epub 2006 Aug 17. Citation on PubMed
  • 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. doi: 10.1002/ajmg.c.30087. Citation on PubMed or Free article on PubMed Central
  • Morales Corado JA, Lee CU, Enns GM. Carnitine-Acylcarnitine Translocase Deficiency. 2022 Jul 21. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Bean LJH, Gripp KW, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. Available from Citation on PubMed
  • 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. doi: 10.1016/s0167-4838(01)00147-9. Citation on PubMed
  • 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. doi: 10.1016/j.mam.2004.06.007. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.