Carnitine Palmitoyltransferase I Deficiency

What is carnitine palmitoyltransferase I deficiency?

Carnitine palmitoyltransferase I deficiency is a condition that prevents the body from converting certain fats called long-chain fatty acids into energy, particularly during periods without food (fasting). Carnitine, a natural substance acquired mostly through the diet, is required by cells to process fats and produce energy. People with this disorder have a faulty enzyme that disrupts carnitine's role in processing long-chain fatty acids.

The main signs of this disorder include low levels of ketones (products of fat breakdown that are used for energy) 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.

This condition is sometimes mistaken for Reye syndrome, a severe disorder that develops 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 carnitine palmitoyltransferase I deficiency?

This condition is rare, there are fewer than 50 individuals identified with this disorder. The incidence of this disorder may be increased in the Hutterite populations of the northern United States and Canada, and in the Inuit populations of northern Canada, Alaska, and Greenland.

What genes are related to carnitine palmitoyltransferase I deficiency?

Mutations in the CPT1A gene cause carnitine palmitoyltransferase I deficiency.

Mutations in the CPT1A gene lead to the production of a defective version of an enzyme called carnitine palmitoyltransferase I. Together with carnitine, this enzyme helps transport long-chain fatty acids into mitochondria, the energy-producing centers within cells. If this enzyme is defective, long-chain fatty acids from food and fats stored in the body cannot be broken down and processed. As a result, these fatty acids are not converted into energy, which can lead to characteristic signs and symptoms of this disorder, such as weakness and hypoketotic hypoglycemia. Excessive levels of long-chain fatty acids may build up in tissues, damaging the liver, heart, and brain.

How do people inherit carnitine palmitoyltransferase I deficiency?

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.

What other names do people use for carnitine palmitoyltransferase I deficiency?

• carnitine palmityltransferase 1 deficiency
• CPT deficiency, hepatic, type I
• CPT I deficiency
• Liver form of carnitine palmitoyltransferase deficiency