Carnitine palmitoyl transferase I (CPT I) deficiency, also called carnitine palmitoyltransferase 1A (CPT 1A) deficiency, CPT deficiency, hepatic, type I, or liver form of carnitine palmitoyltransferase deficiency, is a very rare inherited deficiency of a particular enzyme (Carnitine palmitoyl transferase I) prevents fatty acids being transported to the part of the cell that converts it to energy. There are two main subtypes of the disorder with each involving a slightly different form of the enzyme. Type I can be readily managed through diet.
Source: Genetics home reference
The list of signs and symptoms mentioned in various sources for Carnitine palmitoyl transferase 1 deficiency includes the 13 symptoms listed below:
- Hypoketotic hypoglycemia
- Enlarged liver
- High blood level of carnitine
- Mild metabolic acidosis
- Lactic acidemia
- Increased transaminases
- Low blood sugar
- Loss of consciousness
- Muscle weakness
- Nervous system damage
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.
The definitive diagnosis of CPT I deficiency is made by measuring enzyme activity in fibroblasts, leukocytes, or liver. A variety of mutations have been detected in the gene for hepatic CPT I, but no common mutations have been found to allow easy DNA diagnosis.
After fasting or illness, people with CPT I deficiency are at risk for life-threatening liver failure. These episodes can also cause permanent damage to the brain and liver. However when the disease is carefully managed, people with CPT I deficiency can live fairly normal lives.
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. A corn starch solution consumed regularly overnight will provide a slow release of energy that prevents blood sugar from dipping to dangerously low levels. People with CPT I deficiency should never go long periods without eating.
When hypoglycemia does occur, it needs to be quickly treated with an intravenous sugar solution in order to prevent damage to the brain.
Women who are carriers of CPT I deficiency and become pregnant should undergo testing for liver enzyme levels, especially during times of fasting or illness.
Fatty Oxidation Disorders (FOD) Family Support Group