The only genetic metabolic disorder clearly linked thus far to sudden infant death syndrome (SIDS) is medium-chain acylcoenzyme A dehydrogenase (MCAD) deficiency. There has been no evidence for an association between SIDS and other hereditary metabolic disorders. A few studies, which were often carried out retrospectively on single subjects, have involved the measurement of various metabolites including organic acids, carnitine, free amino acids, and the enzymes implicated in the oxidation of fatty acids, and these have not linked SIDS to inborn errors of metabolism. The study of Harpey et al1 reported that 15% of SIDS infants have a fatty acid β-oxidation defect.
A large neuroblastoma screening study was recently started in the province of Quebec, Canada. This project, a collaboration between the Quebec Network for Genetic Medicine and the University of Minnesota, is studying the impact of screening infants for the preclinical detection of neuroblastoma on the population-based mortality caused by this tumor. All infants born in Quebec during a 5-year period will be screened twice, at 3 weeks and at 6 months. Urinary homovanillic acid and vanillylmandelic acid determination from dried filter paper samples is used for screening. Initial qualitative screening is done by means of thin-layer chromatography with confirmatory quantitative screening by gas chromatography-mass spectrometry (GC-MS). During the initial 6 months of 3-week screening, 41 673 neonates (92% compliance rate) were screened and 10.6% of them were tested also by GC-MS. Nine of these neonates had positive results on two GC-MS tests and were referred for evaluation to rule out the presence of neuroblastoma. Four had the tumor, 1 had a calcified adrenal gland, and 4 had no tumor detected. Three additional neonates had clinical diagnosis of neuroblastoma before they reached the screening age of 3 weeks. A neuroblastoma that did not secrete homovanillic acid or vanillylmandelic acid was diagnosed clinically in 1 additional patient who tested negative by screening.