Carnitine palmitoyltransferase I deficiency
Other names	CPT-I, CPT1
Carnitine

Carnitine palmitoyltransferase I deficiency is a rare metabolic disorder that prevents the body from converting certain fats called long-chain fatty acids(LCFA) into energy, particularly during periods without food. ^[1] It is caused by a mutation in CPT1A on chromosome 11.^{[ citation needed]}

Carnitine, a natural substance acquired mostly through the diet, is used by cells to process fats and produce energy. People with this disorder have a faulty enzyme, carnitine palmitoyltransferase I, that prevents these long-chain fatty acids from being transported into the mitochondria to be broken down.^{[ citation needed]}

Signs and symptoms of this disorder include low levels of ketones (hypoketosis) and low blood sugar ( hypoglycemia). Together these signs are called hypoketotic hypoglycemia. People with this disorder typically also have an enlarged liver ( hepatomegaly), muscle weakness, and elevated levels of carnitine in the blood. ^[2]

Mutations in the CPT1A gene cause carnitine palmitoyltransferase I deficiency by producing a defective version of an enzyme called carnitine palmitoyltransferase I. Without this enzyme, long-chain fatty acids from food and fats stored in the body cannot be transported into mitochondria to be broken down and processed. As a result, excessive levels of long-chain fatty acids may more rapidly build up in tissues, damaging the liver, heart and/or brain.^{[ citation needed]} This condition has an autosomal recessive inheritance pattern, which means the defective gene must be inherited from both parents. The parents of a child with an autosomal recessive disorder are carriers of one copy of the defective gene, but are usually not affected by the disorder.^{[ citation needed]}

The prevalence of mutations associated with this condition reach 68% to 81% in certain arctic coastal populations, suggesting that the condition had some adaptive value in those habitats at some time. ^{[3] [4]} Fewer than 50 people have been identified with this condition. ^[5]

Genetic testing is necessary for diagnosis.

This condition is sometimes mistaken for fatty acid and ketogenesis disorders such as Medium-chain acyl-coenzyme A dehydrogenase deficiency (MCAD), other long-chain fatty acid oxidation disorders such as Carnitine palmitoyltransferase II deficiency (CPT-II) and Reye syndrome. ^[6]

Treatment for this condition is supportive. There is no cure. Affected people should eat a high-carbohydrate, low-fat diet and avoid fasting. ^[7]

• Primary carnitine deficiency
• Carnitine palmitoyltransferase II deficiency

This article incorporates public domain text from The U.S. National Library of Medicine