NEONATAL HYPERAMMONEMIA CAUSED BY A DEFECT OF CARNITINE-ACYLCARNITINETRANSLOCASE

Carnitine-acylcarnitine translocase deficiency is a newly recognized i nborn error of metabolism that involves transport of long-chain fatty acids into mitochondria, which in turn impairs mitochondrial beta-oxid ation, and ketogenesis. We report a new familial example; the affected twins had neonatal distress, hyperammonemia, and transient intracardi ac conduction defects. Clinical and biochemical analysis of both our p atients and the two previously reported patients revealed that this in herited defect could be manifested during the neonatal period without any of the signs classically associated with fatty oxidation defects. In contrast, all four patients had sustained and ''isolated'' hyperamm onemia, which could be misinterpreted as being caused by urea cycle de fects. We conclude that carnitine-acylcarnitine translocase deficiency is a potential differential diagnosis in neonates with unexplained ne onatal hyperammonemia. Cardiac and muscle involvement may represent fu rther early pivotal symptoms.