Carnitine Palmitoyltransferase II Deficiency

Carnitine palmitoyltransferase II (CPT II) deficiency is an inherited disorder in which the body is defective in using certain fats for energy. There are three main types of CPT II deficiency. The first type is the most severe. Symptoms may appear soon after birth, including respiratory failure, seizures, liver failure, weakened heart muscles, irregular heartbeat, brain and kidney abnormalities, low blood sugar levels and a low level of ketones. Individuals affected with this form of CPT II deficiency usually live for a few days to a few months. In the second type, symptoms appear within the first year of life, including an enlarged liver, weakened heart, irregular heartbeat, seizures, low blood sugar levels and a low level of ketones. These problems are often triggered by periods without food (fasting) or illness. Individuals affected with this form of CPT II deficiency are at risk for liver failure, nervous system damage, coma, and sudden death. The third type is the least severe type of CPT II deficiency. Symptoms may appear in infancy, childhood or adulthood. Individuals with this form of CPT II deficiency experience recurrent episodes of muscle pain and weakness after exercise, stress, exposure to extreme temperatures, infections or fasting. In between these episodes, the affected individuals are often symptom free. Generally, intellectual conditions are not affected by CPT II deficiency. Currently, there are no effective treatments for CPT II deficiency. However, the symptoms can be alleviated if the affected individual avoids fasting and exercise, and manages nutrition intake properly. CPT II deficiency is caused by pathogenic variants in the CPT2 gene.

CPT II deficiency is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

There are generally no signs or symptoms associated with being a carrier for CPT II deficiency. However, in rare circumstances, carriers can have symptoms of CPT II deficiency. Carriers have increased risk to have children affected with the CPT II deficiency. Testing of reproductive partners is recommended for carriers of CPT II deficiency.

CPT II deficiency is a rare disorder. Currently, the exact occurence of CPT II is unknown. It is estimated that CPT II is found in less than 1 in 1,000,000 people.

Genetics Home Reference: Carnitine palmitoyltransferase II deficiency (http://ghr.nlm.nih.gov/)

OMIM: [CPT2:600650] (http://www.ncbi.nlm.nih.gov/omim)
GeneReviews: Carnitine palmitoyltransferase II deficiency (http://www.ncbi.nlm.nih.gov/books/NBK1116/)

• Full gene sequencing