carnitine palmitoyltransferase IA deficiency
What Is Carnitine Palmitoyltransferase IA Deficiency?
Carnitine palmitoyltransferase IA (CPT1A) deficiency, caused by mutations in the CPT1A gene, is an inherited disease in which the body cannot convert long-chain fatty acids into energy to fuel the body. Symptoms occur in severe episodes, often during long periods without eating (fasting) and/or during times of fever or gastrointestinal illness.
Symptoms of CPT1A deficiency usually begin in infancy. One key symptom of the disease is low blood sugar (hypoglycemia) combined with low blood levels of ketones, a byproduct of fat breakdown that can be burned for energy. Together, these symptoms are known as hypoketotic hypoglycemia. Prolonged periods of hypoketotic hypoglycemia can lead to loss of consciousness or seizures. Other symptoms of CPT1A deficiency include an enlarged liver (hepatomegaly), muscle weakness, and damage to the liver, heart, and brain due to excess fatty acid buildup. If untreated, these symptoms can be life-threatening.
Though most individuals with CPT1A deficiency will experience episodes of hypoketotic hypoglycemia in infancy or childhood, some may not begin showing symptoms until later in life.
How Common Is Carnitine Palmitoyltransferase IA Deficiency?
CPT1A deficiency is extremely rare. Fewer than 50 cases have been identified worldwide. The disease is thought to be more common among the Hutterite population in the northern United States and Canada as well as the Inuit population in northern Canada, Alaska, and Greenland.
How Is Carnitine Palmitoyltransferase IA Deficiency Treated?
A key goal of treatment is to combat low blood sugar (hypoglycemia). A physician will recommend a modified diet, typically with high-carbohydrate, low-fat foods. Infants will need to eat frequently during the day. Infants can also be given cornstarch overnight in order to provide a slow release of energy that prevents blood sugar from dipping to dangerously low levels.
Individuals with CPT1A deficiency should never go for long periods without eating. When blood sugar is low, it needs to be quickly treated with an intravenous sugar solution in order to prevent damage to the brain. Women who are carriers of CPT1A deficiency and become pregnant should undergo testing for liver-enzyme levels, especially during times of fasting or illness.
What Is the Prognosis for an Individual with Carnitine Palmitoyltransferase IA Deficiency?
After fasting or illness, individuals with CPT1A deficiency can be at risk for life-threatening liver failure. These episodes can also cause permanent damage to the brain and liver. With early diagnosis and careful management, however, individuals with CPT1A deficiency can often have normal or near-normal lives.
Additional Considerations for Carriers
Carriers of fatty-acid oxidation defects, including CPT1A deficiency, do not typically show symptoms of the disease. However, there may be an increased risk of serious pregnancy complications, particularly in the third trimester, in women carrying a fetus affected with a fatty-acid oxidation defect. A woman whose pregnancy may be affected by a fatty-acid oxidation defect, such as CPT1A deficiency, should speak with her physician for recommendations and may benefit from consultation with a high-risk physician.