Carnitine-acylcarnitine translocase (CACT) deficiency is a disorder of long chain fatty acid oxidation. About 30 cases of this disorder have been reported. In most patients the presenting features were neonatal neurological distress (lethargy, poor feeding), cardiac rhythm disorders and hypoketotic hypoglycemia with hyperammonemia. Hepatomegaly and hypertrophic cardiomyopathy may develop secondarily. The disorder is inherited as an autosomal recessive trait. The carnitine-acylcarnitine carrier is an inner mitochondrial membrane protein that catalyzes the mole-to-mole exchange between internal carnitine and external acylcarnitines. Human CACT has been cloned and the structure and organization of the gene have been elucidated. Determination of the blood acylcarnitine profile and in vitro fatty acid oxidation studies in lymphocytes or fibroblasts are the two main ways to establish the diagnosis, which can be confirmed by the specific determination of carnitine-acylcarnitine exchange in digitonin-permeabilized cells. Urine organic acids are more or less informative for the biological diagnosis. Prenatal diagnosis is available by enzymatic or molecular analyses. Treatment mainly involves the blockade of lipolysis and avoiding fasting by glucose infusion or frequent meals and nocturnal nasogastric feeding with a high-carbohydrate/low-fat diet. L-Carnitine supplementation is now also considered helpful. Long chain fatty acid intake should be restricted and medium chain triglycerides should be used instead. CACT deficiency is a severe disease that can cause neonatal or infantile sudden death.
Last update: October 2004