MEDIUM-CHAIN ACYL-COA DEHYDROGENASE-DEFICIENCY DOES NOT CORRELATE WITH APPARENT LIFE-THREATENING EVENTS AND THE SUDDEN-INFANT-DEATH-SYNDROME - RESULTS FROM PHENYLPROPIONATE LOADING TESTS AND DNA ANALYSIS

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is the most comm on inherited disorder of fatty acid metabolism and typically presents in early childhood as potentially fatal hypoketotic, hypo,olycaemic cr isis often associated with Reye-like symptoms. Re-investigations of ca ses of sudden infant death syndrome (SLDS) have revealed in some insta nces a deficiency of MCAD, suggesting that this metabolic disorder may lead to sudden infant death without prior clinical symptoms. In the p resent study, we examined 142 infants who had suffered from an apparen t Life-threatening event (ALTE) or were otherwise considered at risk f or SLDS for MCAD deficiency by phenylpropionate loading. In no case ex cretion of phenylpropionylglycine, the hallmark of MCAD deficiency, wa s increased. In contrast, 3 out of 55 children with symptoms of metabo lic disorders showed increased phenylpropionylglycine excretion, and i n all three cases MCAD deficiency was confirmed by DNA analysis. In ad dition, we investigated 142 cases of sudden unexplained child death an d 100 control subjects for the A985G mutation in the MCAD gene which i s associated with about 98% of enzyme deficiencies. We found one case of heterozygosity each in the patient and control group. Our data indi cate that MCAD deficiency is not a major cause of ALTE and, in agreeme nt with results from similar studies in other countries, its frequency is not increased in children who died of SIDS.