IFITM3 and influenza: Notably, the minor rs12252-C allele in IFITM3, which has an allelic frequency of 0.03 and 0.5 in European white and Han Chinese populations, respectively (16, 17), is associated with impaired restriction of influenza replication (15, 16, 18), increased susceptibility to severe influenza-associated disease (16, 17), and HIV progression (19).