IFITM3 and influenza: Several potential genetic polymorphisms have recently been described for the susceptibility to influenza infection; including genes which encode complement decay-accelerating factor (CD55), complement 1 C1q binding protein (C1QBP), Fc fragment of IgG receptor IIa (FCGR2A), interferon induced transmembrane protein 3 (IFITM3), tumor necrosis factor (TNF), replication protein A interacting protein (RPAIN), lymphotoxin alpha (LTA), and killer-cell inhibitory receptor (KIR) [14–18].