Carnitine-acylcarnitine translocase (also known as CACT) deficiency is a very rare inherited fatty acid oxidation disorder. To date, less than 60 cases have been reported worldwide. This disorder most often follows an autosomal recessive inheritance pattern and usually presents in the neonatal period with severe hypoketotic hypoglycemia, hyperammonemia, cardiomyopathy and/or arrhythmia, hepatic dysfunction, skeletal muscle weakness, and encephalopathy. The prognosis of CACT is poor; many infants with this deficiency do not survive the newborn period.
Mutations in the SLC25A20 gene have been identified in patients with CACT deficiency. SLC25A20 encodes a protein called carnitine-acylcarnitine translocase (CACT), which transports long-chain fatty acid carnitine esters into the mitochondrial matrix. CACT enzyme is an essential component for fatty acid beta-oxidation and energy production in the mitochondria. Deficiency of this transport protein results in impaired long-chain fatty acid oxidation and causes the accumulation of long-chain acylcarnitines outside the mitochondria and in plasma.