Defects in mitochondrial fatty acid oxidation: clinical presentations and their role in sudden infant death.

Defects in mitochondrial beta-oxidation may result in severe metabolic crisis after metabolic stress. The combination of hypoketotic hypoglycaemia and concurrent collapse of mitochondrial metabolic function may be very similar to that in Reye syndrome. Chronic effects on cardiac and skeletal muscle may be seen in some patients with defective long-chain fatty acid oxidation. Less common symptoms include peripheral neuropathy, pigmentary retinopathy, and failure to thrive with recurrent diarrhoea or vomiting. Collectively, such disorders are relatively common and their association with sudden infant death leads to a considerable demand for laboratory investigation. Currently the laboratory methods available are not capable of dealing with this demand in a rational and cost-effective manner and it is necessary to have careful clinically- and pathologically-based selection procedures if a useful service is to result.