IFITM3 rs12252 T>C polymorphism is associated with the risk of severe influenza: a meta-analysis

The interferon-inducible transmembrane protein 3 (IFITM3), as one of the key genes involved in the interferon pathway, is critical for defending the host against influenza virus, and the rs12252 T>C variant in IFITM3 might be associated with susceptibility to severe influenza. Owing to contradictory and inconclusive results, we performed a meta-analysis to assess the association between rs12252 T>C polymorphism and severe influenza risk. A comprehensive literature search up to 1 August 2014 was conducted in EMBASE, Pubmed, Web of Science, VIP, Wanfang and CNKI databases. Four eligible studies with a total of 445 influenza patients and 3396 controls were included in this meta-analysis. Overall, our results demonstrated a significant association between the IFITM3 rs12252 T>C polymorphism and influenza risk [C vs. T: odds ratio (OR) 1.68, 95% confidence interval (CI) 1.32-2.13; CC vs. CT+TT: OR 2.38, 95% CI 1.52-3.73; CC+CT vs. TT: OR 1.62, 95% CI 1.18-2.22]. Stratification by ethnicity indicated that the variant C allele was associated with an 88% increased risk of influenza in Asians (C vs. T: OR 1.88, 95% CI 1.34-2.62). Moreover, subjects carrying the variant C allele had an increased risk of developing severe illness upon influenza infection (C vs. T: OR 2.70, 95% CI 1.86-3.94). However, no significant association was observed in patients with mild infection (C vs. T: OR 1.26, 95% CI 0.93-1.71). Our meta-analysis suggests that IFITM3 rs12252 T>C polymorphism is significantly associated with increased risk of severe influenza but not with the chance of initial virus infection.