No association of SIDS with two polymorphisms in genes relevant for the noradrenergic system: COMT and DBH

Aim: Recent research suggests that genetic variance determining the strength of noradrenergic transmitting might contribute to the aetiology of SIDS. We have typed 2 functional polymorphisms of relevance for both biosynthesis and catabolism of noradrenalin: The Val158Met single-nucleotide polymorphism (SNP) of the Catechol-O-methyl transferase gene (COMT) and the 1021C/T SNP of the dopamine dehydroxylase gene (DBH). Methods: COMT and DBH were typed in 171 and 196 SIDS cases and 213 and 244 controls, respectively, using PCR followed by digestion with restriction enzymes. Typing was performed using a QIAxcel automatic electrophoresis unit. Results: Both SNPs were in Hardy-Weinberg equilibrium, and for none of these polymorphisms, an association with SIDS could be demonstrated. The allelic frequencies of the DBH locus were C: 78.32% and T: 21.68% in SIDS and C: 77.66% and T: 22.34% in controls. For the COMT locus, the allelic frequencies were A: 51.17% and G: 48.83% in SIDS and A: 52.82% and G: 47.18% in controls. Conclusion: Despite these negative results, the noradrenergic system is still an attractive candidate as modulator of SIDS risk to our eyes. There are several genes involved in this system that have not been studied up to now.