[Screening of A985 to G mutation of medium-chain acyl-CoA dehydrogenase (MCAD) gene in Normandy. Evaluation of the role of MCAD deficiency in sudden infant death].

MCAD deficiency is recognized as the most common hereditary defect of hepatic fatty acid oxidation. Clinical signs are somnolence progressing to lethargy potentially leading to coma. Death is the outcome of the first attack in about 20% of cases, suggesting sudden infant death syndrome (SIDS). A point mutation (adenine to guanine at position 985) in exon 11 of the MCAD gene represents 90% of alleles causing MCAD deficiency. The high prevalence of this mutation allows the estimation of the incidence of MCAD deficiency in the general population and in SIDS. The study was performed after PCR amplification from blood spots on filter paper in 1,432 randomly selected newborns (group I), in 225 SIDS (group II) and in 47 infants of SIDS family (group III). In group I, 10 newborns were found to have the G985 mutation in the heterozygous form. In group II, among 225 SIDS cases, the G985 MCAD mutation was found once in the heterozygote state. In group III, the mutation was not found. The estimated frequency of the mutation was 1/143 in the reference group and the incidence of MCAD deficiency was calculated as 1/67,000 in Normandy.