COL1A1 and osteogenesis imperfecta: Variants in COL1A1 and COL1A2 were the most commonly detected alterations responsible for OI (71.6% and 25.6%, respectively); nevertheless, variants in non-collagen genes (CRTAP, FKBP10, IFITM5, LEPRE1, PLS3, SERPINF1) were found in 2.7% of the patients.