IFITM5 and osteogenesis imperfecta: Following reports stating that no major abnormality is seen in the osteogenesis of Ifitm5-deficient mice, many research groups have reported that patients with osteogenesis imperfecta (OI) type V have a heterozygous point mutation (c.-14C > T) in the 5 ' untranslated region of the IFITM5 gene5–16.