Acyl-CoA dehydrogenase, medium chain (MCAD) deficiency is a congenital metabolic disorder that affects the mitochondrial fatty acid beta-oxidation pathway. Fatty acid oxidation, which fuels hepatic ketogenesis, is an essential process that converts certain fats into energy, particularly when carbohydrates are scarce. In hepatic cells, ketogenesis is the major source of energy after the depletion of hepatic glycogen, during prolonged fasting, and periods of high energy demands. Several enzymes work in a step-wise fashion during fatty acid oxidation. Due to defects in the ACADM gene, patients with MCAD deficiency have inadequate levels of medium-chain acyl-CoA dehydrogenase enzyme required for metabolizing a group of fats called medium-chain fatty acids. This results in the accumulation of medium-chain fatty acids in various tissues causing serious complications.
MCAD deficiency has an early onset and it is characterized by hypoketotic hypoglycemia, vomiting, and lethargy triggered by fasting or certain viral infections. In addition, serious complications can also be associated with MCAD deficiency such as seizures, breathing difficulties, liver problems, brain damage, coma, and sudden unexpected death.