First description of a type v osteogenesis imperfecta clinical case with severe skeletal deformities caused by a mutation p.119C> T in IFITM5 gene in Russia

Osteogenesis imperfecta (OI) is a hereditary connective tissue disorder. Main clinical manifestations include recurring pathological fractures and progressive skeletal deformation. Five types of OI are distinguished based on clinical symptoms. In most cases, the disease is caused by mutations in the COL1A1 and COL1A2 genes, leading to a defect of type 1 collagen synthesis, which is the main component of the bone matrix. Up to 5% of patients with OI have a mutation in IFITM5 gene, which leads to the development of OI type V. Approximately 150 cases of the OI type V are described in the literature, and mutation c.-14C T in IFITM5 gene is found in most of the cases. Only 5 patients have a c.119C T: p.S40L.mutation. Pathogenesis of OI type V is not fully understood. It is assumed that mutations in the IFITM5 gene cause impaired osteoblastogenesis, decreased bone mineral density and multiple low-traumatic fractures. There is probably a phenotype-genotypic correlation in cases with different mutations of the IFITM5. However, it is currently difficult to assess the relationship in view of the variability of the characters and the low prevalence of the OI type V. We present the first description in Russia of the clinical case of an adult patient with OI type V due to a rare mutation p.119C T: p.S40L in the IFITM5 gene.