Aquaporin-4 gene variation and sudden infant death syndrome.

The purpose of this study was to investigate the aquaporin-4 (AQP4) gene in cases of sudden infant death syndrome (SIDS) and controls and to elucidate the hypothesis that a genetically determined disturbed water homeostasis in the brain is involved as a predisposing factor in SIDS. The single nucleotide polymorphisms (SNPs) rs2075575, rs4800773, rs162004, and rs3763043 in the AQP4 gene were investigated in 141 SIDS cases and 179 controls. For each SIDS case, a brain/body weight ratio was calculated. The study revealed an association between the T allele and the CT/TT genotypes of rs2075575 and SIDS (C versus T, p < 0.01; CC versus CT/TT, p = 0.03). For the other three investigated SNPs, there were no differences in genotype frequencies between SIDS cases and controls. For the SNP rs2075575, it was also found an association between brain/body weight ratio and genotype in the SIDS cases aged 0.3-12 wk (p = 0.014, median ratio CC 10.6, CT/TT 12.1). In conclusion, this study indicates that rs2075575 may be of significance as a predisposing factor for SIDS, and that the CT/TT genotypes are associated with an increased brain/body weight ratio in infants dying from SIDS during the vulnerable period from birth up to 3 mo of age.