Neonatal carnitine palmitoyltransferase II deficiency: failure of treatment despite prolonged survival.

Carnitine palmitoyltransferase (CPT) deficiencies are disorders of mitochondrial fatty acid oxidation (FAO). In fatty acid oxidation, long-chain fatty acids need the carnitine cycle to be transported from the cytosol to the mitochondria. In CPT II deficiency, long-chain acylcarnitines cannot be metabolised to carnitine and acyl-CoA, leading to accumulation of toxic long-chain acylcarnitines. Three clinical presentations of CPT II deficiency have been identified: the adult form, the infantile form and the neonatal form. The neonatal form of CPT II is the most severe and all reported patients died within a few days to 6 weeks after birth. The first case of a patient with neonatal CPT II deficiency surviving beyond the neonatal period is described. Unfortunately, the infant died at the age of 6 months due to untreatable cardiac arrhythmias.