Primary carnitine deficiency (Primary carnitine deficiency) - Gen SLC22A5.

Primary carnitine deficiency is a condition that prevents the body assimilates certain fats for energy, particularly during periods of fasting. Carnitine, a natural substance primarily acquired through the diet, is used by cells to process fats and produce energy. Signs and symptoms of primary carnitine deficiency usually appear during infancy or early childhood and may include encephalopathy, cardiomyopathy, confusion, vomiting, muscle weakness and hypoglycemia. The severity of this disease varies among affected individuals. Some people are asymptomatic. All individuals with primary carnitine deficiency are at risk for heart failure, liver problems, coma and sudden death.

Problems related to primary carnitine deficiency can be triggered by periods of fasting or diseases, such as viral infections. Sometimes this condition is confused with Reye syndrome. Most cases of Reye 's syndrome associated with aspirin use during viral infections.

This disease is due to mutations in SLC22A5 gene, located on the long arm of chromosome 5 (5q23.3). This gene encodes a protein called OCTN2 transports carnitine in that cell. Cells need carnitine to transport fatty acids into the mitochondria. Fatty acids are an important source of energy for the heart and muscles. During periods of fasting, the fatty acids are also an important source of energy source for the liver and other tissues.

They have identified 60 mutations in the SLC22A5 gene in people with primary carnitine deficiency. Some of these mutations create a premature stop signal in the coding of the OCTN2 protein, resulting in an abnormally short, nonfunctional protein. Other mutations change the amino acids in protein OCTN2. Mutations in the gene give rise to an absent or dysfunctional protein OCTN2. Consequently, there is a deficiency of carnitine in the cells. Without carnitine, fatty acids can not enter the mitochondria and used for energy production, which can lead to some of the characteristics of primary carnitine deficiency, such as muscle weakness and hypoglycaemia. Fatty acids may also accumulate in the cells and damage the liver, heart and muscles. This abnormal accumulation causes the other signs and symptoms of the disease.

The primary carnitine deficiency is inherited as an autosomal recessive pattern, meaning that two copies of the gene in each cell have mutations. Too often, parents of a person with an autosomal recessive disorder are carriers, which means that each carry one copy of the mutated gene. Carriers of mutations in the SLC22A5 gene can have some signs and symptoms related to the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with primary carnitine deficiency, by complete PCR amplification of exons SLC22A5 gene, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).