Meta-analysis of the Association between Serotonin Transporter Polymorphisms and Sudden Infant Death Syndrome

Abstract

The serotonin transporter (5-HTT) gene has been considered one of the risk factors for sudden infant death syndrome (SIDS), but the association remains unconfirmed. This meta-analysis was performed to quantitatively summarize the evidence for such a relationship. PubMed, EMBASE, and China National Knowledge Infrastructure databases were searched for eligible studies within a range of published years from 1990 to December 2015. The odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the different associations. A total of 8 studies with 624 cases and 796 controls were included for 5-HTT promoter polymorphism, 5 studies with 418 cases and 542 controls for intron 2, and 3 studies with 253 cases and 334 controls for haplotype. The pooled examinations showed an overall increased SIDS risk for the 5-HTT promoter polymorphism (OR = 1.65, 95% CI = 1.03-2.63, P = 0.035 for LL vs. LS and SS; OR = 1.46, 95% CI = 1.04-2.04, P = 0.028 for L vs. S), but no association (OR = 1.00, 95% CI = 0.75-1.33, P = 0.994 for 10 + 9 carriers vs. 12/12; OR = 0.97, 95% CI = 0.79-1.19, P = 0.753 for 10 + 9 vs. 12) for intron 2 polymorphism, and an unreliable association (OR = 0.52, 95% CI = 0.31-0.87, P = 0.013) for S-9 and S-10 haplotypes. This meta-analysis suggests that the L allele or LL homozygote of 5-HTT promoter polymorphism has an increased risk for SIDS, while intron 2 polymorphism has no association with SIDS.