The A subfamily regroups all IFITMs which in humans are IFITM1, 2, and 3, which we will refer to hereafter as IFITMs, that are IFN-induced proteins essentially studied in the context of viral infection (3); IFITM5 that plays undefined roles in Osteogenesis imperfecta type V, a bone-specific disease (4) and IFITM10 whose functions are unknown. Here, IFITM5 is linked to osteogenesis imperfecta type 5.