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CPT1A gene
URL of this page: https://medlineplus.gov/genetics/gene/cpt1a/

CPT1A gene

carnitine palmitoyltransferase 1A

Normal Function

The CPT1A gene provides instructions for making an enzyme called carnitine palmitoyltransferase 1A, which is found in the liver. This enzyme is essential for fatty acid oxidation, a multistep process that breaks down (metabolizes) fats and converts them into energy. During periods of fasting, long-chain fatty acids are an important energy source for the liver and other tissues. Within liver cells, fatty acid oxidation takes place within mitochondria, which are the energy-producing centers. Before entering mitochondria, a group of fats called long-chain fatty acids must first be attached to a substance known as carnitine. Carnitine palmitoyltransferase 1A connects carnitine to long-chain fatty acids so they can cross the inner membrane of mitochondria. Inside mitochondria, carnitine is removed from the fatty acids, and they can be metabolized to produce energy.

Health Conditions Related to Genetic Changes

Carnitine palmitoyltransferase I deficiency

Variants (also called mutations) in the CPT1A gene have been found to cause carnitine palmitoyltransferase I (CPT I) deficiency. CPT I deficiency is a condition that prevents the body from using certain fats for energy. This condition can cause serious health problems, particularly during periods of fasting.

Most of the CPT1A gene variants lead to changes in single protein building blocks (amino acids) within carnitine palmitoyltransferase 1A. These changes severely reduce or eliminate the activity of this enzyme. As a result, there are not enough enzymes available to attach carnitine to long-chain fatty acids when energy demands are high. Without carnitine, these fatty acids cannot enter mitochondria to be broken down and used for energy. Reduced energy production can lead to some of the features of CPT I deficiency, such as low levels of glucose in the blood (hypoglycemia) and low levels of the products of fat breakdown (hypoketosis). Fatty acids may also build up in cells and damage the liver, heart, and brain. This abnormal buildup causes the other signs and symptoms of the disorder.

More About This Health Condition

Other disorders

CPT1A gene variants appear to increase the risk of a serious liver disorder that can develop in women during pregnancy. This disorder, called acute fatty liver of pregnancy (AFLP), begins with abdominal pain and can rapidly progress to liver failure. Signs of AFLP include an abnormal accumulation of fat in the liver, hypoglycemia, increased levels of ammonia in the blood (hyperammonemia), and abnormalities in liver enzymes.

A small percentage of women who have a variant in one copy of the CPT1A gene in each cell and who are pregnant with a fetus who has variants in both copies of the CPT1A gene develop AFLP. Little is known about the relationship between CPT1A gene variants and liver problems during pregnancy.

Other Names for This Gene

  • carnitine palmitoyltransferase 1A (liver)
  • carnitine palmitoyltransferase I, liver
  • CPT1
  • CPT1-L
  • CPT1A_HUMAN
  • L-CPT1

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases

References

  • Akkaoui M, Cohen I, Esnous C, Lenoir V, Sournac M, Girard J, Prip-Buus C. Modulation of the hepatic malonyl-CoA-carnitine palmitoyltransferase 1A partnership creates a metabolic switch allowing oxidation of de novo fatty acids. Biochem J. 2009 May 27;420(3):429-38. doi: 10.1042/BJ20081932. Citation on PubMed
  • Balci MC, Karaca M, Selamioglu A, Korbeyli HK, Durmus A, Ak B, Kozanoglu T, Gokcay GF. A different perspective into clinical symptoms in CPT I deficiency. Mol Genet Metab Rep. 2023 Nov 30;38:101032. doi: 10.1016/j.ymgmr.2023.101032. eCollection 2024 Mar. Citation on PubMed
  • Bennett MJ, Boriack RL, Narayan S, Rutledge SL, Raff ML. Novel mutations in CPT 1A define molecular heterogeneity of hepatic carnitine palmitoyltransferase I deficiency. Mol Genet Metab. 2004 May;82(1):59-63. doi: 10.1016/j.ymgme.2004.02.004. Citation on PubMed
  • Bonnefont JP, Djouadi F, Prip-Buus C, Gobin S, Munnich A, Bastin J. Carnitine palmitoyltransferases 1 and 2: biochemical, molecular and medical aspects. Mol Aspects Med. 2004 Oct-Dec;25(5-6):495-520. doi: 10.1016/j.mam.2004.06.004. Citation on PubMed
  • Brown NF, Mullur RS, Subramanian I, Esser V, Bennett MJ, Saudubray JM, Feigenbaum AS, Kobari JA, Macleod PM, McGarry JD, Cohen JC. Molecular characterization of L-CPT I deficiency in six patients: insights into function of the native enzyme. J Lipid Res. 2001 Jul;42(7):1134-42. Citation on PubMed
  • Gobin S, Bonnefont JP, Prip-Buus C, Mugnier C, Ferrec M, Demaugre F, Saudubray JM, Rostane H, Djouadi F, Wilcox W, Cederbaum S, Haas R, Nyhan WL, Green A, Gray G, Girard J, Thuillier L. Organization of the human liver carnitine palmitoyltransferase 1 gene ( CPT1A) and identification of novel mutations in hypoketotic hypoglycaemia. Hum Genet. 2002 Aug;111(2):179-89. doi: 10.1007/s00439-002-0752-0. Epub 2002 Jul 16. Citation on PubMed
  • Gobin S, Thuillier L, Jogl G, Faye A, Tong L, Chi M, Bonnefont JP, Girard J, Prip-Buus C. Functional and structural basis of carnitine palmitoyltransferase 1A deficiency. J Biol Chem. 2003 Dec 12;278(50):50428-34. doi: 10.1074/jbc.M310130200. Epub 2003 Sep 29. Citation on PubMed
  • Lee K, Pritchard A, Ahmad A. Carnitine Palmitoyltransferase 1A Deficiency. 2005 Jul 27 [updated 2025 Feb 20]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. Available from http://www.ncbi.nlm.nih.gov/books/NBK1527/ 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
  • Ramsay RR, Zammit VA. Carnitine acyltransferases and their influence on CoA pools in health and disease. Mol Aspects Med. 2004 Oct-Dec;25(5-6):475-93. doi: 10.1016/j.mam.2004.06.002. Citation on PubMed
  • Vockley J. Long-chain fatty acid oxidation disorders and current management strategies. Am J Manag Care. 2020 Aug;26(7 Suppl):S147-S154. doi: 10.37765/ajmc.2020.88480. 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.