Carnitine palmitoyltransferase I deficiency

Carnitine palmitoyltransferase I deficiency is a rare condition that prevents the body from converting certain fats called long-chain fatty acids into energy, particularly during periods without food. 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 that prevents these long-chain fatty acids from being transported into the mitochondria to be broken down.

Signs
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.

Differential diagnosis
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.

Causes
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. 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 build up in tissues, damaging the liver, heart, and brain.

This condition is inherited in an autosomal recessive pattern.