Genetic studies have confirmed that type V OI was caused by a point mutation in the 5′ UTR of IFITM5 gene (c.-14C>T), resulting in the addition of 5 amino acids (Met-Ala-Leu-Glu-Pro, MALEP) at its N-terminus.9–12. The gene discussed is IFITM5; the disease is osteogenesis imperfecta type 5.