1276 MEDIUM CHAIN ACYL CoA DEHYDROGENASE DEFICIENCY: EVIDENCE FOR AUTOSOMAL RECESSIVE INHERITANCE AND A URINARY MARKER FOR SCREENING

Abstract

A 3 1/2 year old white male presented with a history of recurrent severe nonketotic hypoglycemia. Evaluation revealed C6-C10 dicarboxylic aciduria and low serum levels of total carnitine (16.2 n moles/ml), free carnitine (6.2 n moles/ml), and short chain acyl carnitine (5.9 n moles/ml). Urinary carnitine was also low (919 n moles/24hr) but showed markedly increased acyl carnitine to free carnitine ratio (10.9 to 1; normal approx. 0.65 to 1). These findings are indicative of medium chain acyl CoA dehydrogenase deficiency. Family history revealed that a female sibling died at age 10 mos after a sudden collapse during a minor illness. Her autopsy revealed an intraocular glucose of 0 mg/dl (indicating severe hypoglycemia at the time of death) and increased vacuolated fat was observed in the liver and skeletal muscle. These findings are also consistent with medium chain acyl CoA dehydrogenase deficiency. Previous reports in the literation include a pair of fraternal twins with a similar defect in medium chain acyl CoA dehydrogenation and a patient with short chain acyl CoA dehydrogenase deficiency with an elevated urinary acyl carnitine to free carnitine ration of 3.48 to 1. We conclude that, 1) medium chain acyl CoA dehydrogenase deficiency may be inherited as an autosomal recessive; and 2) the urinary acyl carnitine to free carnitine ratio may be a useful non-invasive screen for these conditions.