Sudden infant death: no evidence for linkage to common polymorphisms in the uncoupling protein-1 and the beta3-adrenergic receptor genes

Thermal stress has been postulated to play a major role in the aetiology of sudden infant death (SID). The human uncoupling protein-1 (UCP-1), expressed in brown adipose tissue dissipates the transmitochondrial proton gradient as heat and plays a central role in energy homeostasis and thermogenesis. A common Bcl I polymorphism in the promoter region of the UCP-1 gene is associated with reduced UCP-1 adipose tissue mRNA and obesity. In addition, a common sequence variation in the beta3-adrenergic receptor gene (beta3-AR), Trp64Arg, has been linked to a decreased resting metabolic rate. To determine whether the UCP-1 Bcl I polymorphism and/or the Trp64Arg variant of beta3-AR are associated with the occurrence of SID, we determined the allele frequencies of these polymorphisms in 53 Austrian SID victims and 54 controls by nested PCR and restriction digestion using DNA extracted from Guthrie cards. We found that the allele frequencies of both polymorphisms did not differ between the SID and control groups (0.65/0.35 versus 0.72/0.28 for UCP-1 Bcl I, and 0.89/0.11 versus 0.93/0.07 for beta3-AR Trp64Arg in SID victims versus controls, respectively).

Our data do not support a major association between the occurrence of sudden infant death and two common functional polymorphisms in the human uncoupling protein-1 and beta3-adrenergic receptor genes.