Individuals with OI type I often carry a pathogenic variant caused by a quantitative defect that results from haploinsufficiency, while individuals with OI types II, III and IV typically harbor pathogenic variants that result in a structurally abnormal collagen type I protein, leading to a qualitative defect in collagen type I. OI type V is specifically caused by a pathogenic variant in the 5’ UTR region of the IFITM5(OMIM #614757) gene, which encodes a protein involved in bone formation and mineralization [2]. Here, IFITM5 is linked to osteogenesis imperfecta type 5.