No Correlation of the Disease Severity of Influenza A Virus Infection with the rs12252 Polymorphism of the Interferon-Induced Transmembrane Protein 3 Gene.

The 2009 H1N1 influenza pandemic, which involved a more pathogenic virus than seasonal influenza viruses, rapidly spread around the world and caused many deaths in humans. The members of the interferon-induced transmembrane (IFITM) protein family prevent viral replication and are crucial for defending the host cell against influenza A virus (IAV). Several studies suggest that the CC genotype at the single nucleotide polymorphism (SNP) rs12252 of IFITM3 confers a genetic predisposition to pandemic influenza A in Europeans and Han Chinese, although one study in a British cohort failed to show an association. In order to examine whether an SNP of the IFITM3 gene is correlated with the disease severity of pandemic IAV (H1N1) infection in a Korean population, we investigated the genotype and allele frequencies of this polymorphism in 300 healthy Koreans by automatic direct sequencing and compared the disease severity based on epidemiological studies of the H1N1 virus reported in several countries. The frequencies of the CC genotype and the C allele in the IFITM3 polymorphism were higher in the Korean population than in the European populations, but not in Chinese and Japanese populations. The prevalence of severe cases of the pandemic 2009 IAV infection in Koreans was similar to that in Europeans (p = 0.106). In addition, the prevalence of deaths among all positive cases with pandemic 2009 IAV infection in Koreans was significantly lower than that in Europeans. These results suggest that the IFITM3 genotype may not be a determinant of disease severity of IAV infection.