(often shortened to CPT I deficiency)
Reviewed November 2010
What is CPT I deficiency?
Carnitine palmitoyltransferase I (CPT I) deficiency is a condition that prevents the body from using certain fats for energy, particularly during periods without food (fasting). The severity of this condition varies among affected individuals.
Signs and symptoms of CPT I deficiency often appear during early childhood. Affected individuals usually have low blood sugar (hypoglycemia) and a low level of ketones, which are produced during the breakdown of fats and used for energy. Together these signs are called hypoketotic hypoglycemia. People with CPT I deficiency can also have an enlarged liver (hepatomegaly), liver malfunction, and elevated levels of carnitine in the blood. Carnitine, a natural substance acquired mostly through the diet, is used by cells to process fats and produce energy. Individuals with CPT I deficiency are at risk for nervous system damage, liver failure, seizures, coma, and sudden death.
Problems related to CPT I deficiency can be triggered by periods of fasting or by illnesses such as viral infections. This disorder is sometimes mistaken for Reye syndrome, a severe disorder that may develop in children while they appear to be recovering from viral infections such as chicken pox or flu. Most cases of Reye syndrome are associated with the use of aspirin during these viral infections.
How common is CPT I deficiency?
CPT I deficiency is a rare disorder; fewer than 50 affected individuals have been identified. This disorder may be more common in the Hutterite and Inuit populations.
What genes are related to CPT I deficiency?
Mutations in the CPT1A gene cause CPT I deficiency. This gene provides instructions for making an enzyme called carnitine palmitoyltransferase 1A, which is found in the liver. Carnitine palmitoyltransferase 1A is essential for fatty acid oxidation, which is the 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 cannot enter mitochondria unless they are attached to carnitine. Carnitine palmitoyltransferase 1A connects carnitine to long-chain fatty acids so they can enter mitochondria and be used to produce energy. During periods of fasting, long-chain fatty acids are an important energy source for the liver and other tissues.
Mutations in the CPT1A gene severely reduce or eliminate the activity of carnitine palmitoyltransferase 1A. Without enough of this enzyme, carnitine is not attached to long-chain fatty acids. As a result, these fatty acids cannot enter mitochondria and be converted into energy. Reduced energy production can lead to some of the features of CPT I deficiency, such as hypoketotic hypoglycemia. 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.
Changes in this gene are associated with carnitine palmitoyltransferase I deficiency.
How do people inherit CPT I deficiency?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
Where can I find information about diagnosis or management of CPT I deficiency?
These resources address the diagnosis or management of CPT I deficiency and may include treatment providers.
- FOD Family Support Group: Diagnostic Approach to Disorders of Fat Oxidation - Information for Clinicians (http://www.fodsupport.org/clinicians.htm)
- Gene Review: Carnitine Palmitoyltransferase IA Deficiency (http://www.ncbi.nlm.nih.gov/books/NBK1527/)
- Genetic Testing Registry: Carnitine palmitoyltransferase I deficiency (http://www.ncbi.nlm.nih.gov/gtr/conditions/C0342789)
You might also find information on the diagnosis or management of CPT I deficiency in
Educational resources (http://www.ghr.nlm.nih.gov/condition/carnitine-palmitoyltransferase-i-deficiency/show/Educational+resources) and Patient support (http://www.ghr.nlm.nih.gov/condition/carnitine-palmitoyltransferase-i-deficiency/show/Patient+support).
General information about the diagnosis (http://ghr.nlm.nih.gov/handbook/consult/diagnosis) and management (http://ghr.nlm.nih.gov/handbook/consult/treatment) of genetic conditions is available in the Handbook.
Read more about genetic testing (http://ghr.nlm.nih.gov/handbook/testing), particularly the difference between clinical tests and research tests (http://ghr.nlm.nih.gov/handbook/testing/researchtesting).
To locate a healthcare provider, see How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.
Where can I find additional information about CPT I deficiency?
You may find the following resources about CPT I deficiency helpful. These materials are written for the general public.
MedlinePlus - Health information
- Health Topic: Metabolic Disorders (http://www.nlm.nih.gov/medlineplus/metabolicdisorders.html)
- Health Topic: Newborn Screening (http://www.nlm.nih.gov/medlineplus/newbornscreening.html)
- Genetic and Rare Diseases Information Center - Information about genetic conditions and rare diseases (http://rarediseases.info.nih.gov/gard/1120/resources/resources/1)
Educational resources - Information pages
- Children Living with Inherited Metabolic Diseases (CLIMB): Carnitine Palmitoyltransferase I Deficiency Fact Sheet (http://www.climb.org.uk/IMD/Charlie/CarnitinePalmitoylTransferaseDeficiencyType%201.pdf)
- Iowa Department of Public Health (http://idph.state.ia.us/genetics/common/pdf/cpt1.pdf)
- New England Consortium of Metabolic Programs (http://newenglandconsortium.org/for-families/other-metabolic-disorders/fatty-acid-oxidation-disorders/cpt-i-deficiency/)
- Orphanet (http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Lng=EN&Expert=156)
- Screening, Technology, and Research in Genetics (http://www.newbornscreening.info/Parents/fattyaciddisorders/CPT1.html)
Patient support - For patients and families
- Children Living with Inherited Metabolic Diseases (CLIMB) (http://www.climb.org.uk/)
- Fatty Oxidation Disorders Family Support Group (http://www.fodsupport.org/index.htm)
- National Organization for Rare Disorders (http://www.rarediseases.org/rare-disease-information/rare-diseases/byID/915/viewAbstract)
- United Mitochondrial Disease Foundation (http://www.umdf.org/site/c.8qKOJ0MvF7LUG/b.7929671/k.BDF0/Home.htm)
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
- Gene Reviews - Clinical summary (http://www.ncbi.nlm.nih.gov/books/NBK1527/)
Genetic Testing Registry - Repository of genetic test information
- Genetic Testing Registry: Carnitine palmitoyltransferase I deficiency (http://www.ncbi.nlm.nih.gov/gtr/conditions/C0342789)
ACT Sheets - Newborn screening follow up
- Elevated C0/C16+C18 (http://www.ncbi.nlm.nih.gov/books/NBK55827/bin/C0_C16_C18.pdf)
- PubMed - Recent literature (http://www.ncbi.nlm.nih.gov/pubmed?term=((carnitine%20palmitoyltransferase%201a%20deficiency%5BALL%5D)%20OR%20(carnitine%20palmitoyltransferase%201%20deficiency%5BALL%5D)%20OR%20(CPT1A%20deficiency%5BALL%5D)%20OR%20(carnitine%20palmitoyltransferase%20type%201a))%20AND%20human%5Bmh%5D)
- OMIM - Genetic disorder catalog (http://omim.org/entry/255120)
What other names do people use for CPT I deficiency?
- carnitine palmitoyltransferase IA deficiency
- CPT 1A deficiency
- CPT deficiency, hepatic, type I
- liver form of carnitine palmitoyltransferase deficiency
For more information about naming genetic conditions, see the Genetics Home Reference
Condition Naming Guidelines (http://ghr.nlm.nih.gov/ConditionNameGuide)
How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
What if I still have specific questions about CPT I deficiency?
Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/GARD/).
What glossary definitions help with understanding CPT I deficiency?
autosomal recessive ;
fatty acids ;
liver failure ;
nervous system ;
newborn screening ;
You may find definitions for these and many other terms in the Genetics Home Reference
- 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. (http://www.ncbi.nlm.nih.gov/pubmed/19302064?dopt=Abstract)
- 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. (http://www.ncbi.nlm.nih.gov/pubmed/15110323?dopt=Abstract)
- 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. (http://www.ncbi.nlm.nih.gov/pubmed/11441142?dopt=Abstract)
- 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. Epub 2003 Sep 29. (http://www.ncbi.nlm.nih.gov/pubmed/14517221?dopt=Abstract)
- Greenberg CR, Dilling LA, Thompson GR, Seargeant LE, Haworth JC, Phillips S, Chan A, Vallance HD, Waters PJ, Sinclair G, Lillquist Y, Wanders RJ, Olpin SE. The paradox of the carnitine palmitoyltransferase type Ia P479L variant in Canadian Aboriginal populations. Mol Genet Metab. 2009 Apr;96(4):201-7. doi: 10.1016/j.ymgme.2008.12.018. Epub 2009 Feb 13. (http://www.ncbi.nlm.nih.gov/pubmed/19217814?dopt=Abstract)
- Innes AM, Seargeant LE, Balachandra K, Roe CR, Wanders RJ, Ruiter JP, Casiro O, Grewar DA, Greenberg CR. Hepatic carnitine palmitoyltransferase I deficiency presenting as maternal illness in pregnancy. Pediatr Res. 2000 Jan;47(1):43-5. (http://www.ncbi.nlm.nih.gov/pubmed/10625081?dopt=Abstract)
- 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. (http://www.ncbi.nlm.nih.gov/pubmed/16602102?dopt=Abstract)
- Olpin SE, Allen J, Bonham JR, Clark S, Clayton PT, Calvin J, Downing M, Ives K, Jones S, Manning NJ, Pollitt RJ, Standing SJ, Tanner MS. Features of carnitine palmitoyltransferase type I deficiency. J Inherit Metab Dis. 2001 Feb;24(1):35-42. (http://www.ncbi.nlm.nih.gov/pubmed/11286380?dopt=Abstract)
- OMIM: CARNITINE PALMITOYLTRANSFERASE I DEFICIENCY (http://omim.org/entry/255120)
- Prasad C, Johnson JP, Bonnefont JP, Dilling LA, Innes AM, Haworth JC, Beischel L, Thuillier L, Prip-Buus C, Singal R, Thompson JR, Prasad AN, Buist N, Greenberg CR. Hepatic carnitine palmitoyl transferase 1 (CPT1 A) deficiency in North American Hutterites (Canadian and American): evidence for a founder effect and results of a pilot study on a DNA-based newborn screening program. Mol Genet Metab. 2001 May;73(1):55-63. (http://www.ncbi.nlm.nih.gov/pubmed/11350183?dopt=Abstract)
- Prip-Buus C, Thuillier L, Abadi N, Prasad C, Dilling L, Klasing J, Demaugre F, Greenberg CR, Haworth JC, Droin V, Kadhom N, Gobin S, Kamoun P, Girard J, Bonnefont JP. Molecular and enzymatic characterization of a unique carnitine palmitoyltransferase 1A mutation in the Hutterite community. Mol Genet Metab. 2001 May;73(1):46-54. (http://www.ncbi.nlm.nih.gov/pubmed/11350182?dopt=Abstract)
- Rajakumar C, Ban MR, Cao H, Young TK, Bjerregaard P, Hegele RA. Carnitine palmitoyltransferase IA polymorphism P479L is common in Greenland Inuit and is associated with elevated plasma apolipoprotein A-I. J Lipid Res. 2009 Jun;50(6):1223-8. doi: 10.1194/jlr.P900001-JLR200. Epub 2009 Jan 29. (http://www.ncbi.nlm.nih.gov/pubmed/19181627?dopt=Abstract)
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
See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.