COL1A1 and osteogenesis imperfecta: Due to Estonia’s small population (1.3 million) and centered treatment, follow-up, and research of all OI patients at the OI Center of the Traumatology and Orthopedics Clinic, Tartu University (TU) Hospital, it was possible to perform analysis of COL1A1/2 mutations among the whole Estonian OI population [22].