It has been shown that the binding of IFITM5 to FKBP11 disrupts binding of CD9 with the FKBP11-CD81-CD9/FPRP complex and increases expression of interferon-induced genes.9,10 Thus, there may be an immune component to OI type V clinical manifestations. This evidence concerns the gene PTGFRN and osteogenesis imperfecta type 5.