In 2012, a heterozygous mutation (c.-14C>T) in the 5’-untranslated region (UTR) of the IFITM5 gene was identified as the main cause of OI type V, greatly simplifying the diagnosis, and in 2014, a c.119C>T mutation was identified, with minor differences in the phenotype. The gene discussed is IFITM5; the disease is osteogenesis imperfecta type 5.