SCN9A and osteogenesis imperfecta: Three patients from two independent consanguineous families with clinical features suggestive of OI proved to have mutations in SCN9A (two patients) and NRTK1 (one patient) which are associated with CIP, and an additional patient had a missense change in the FBS gene SLC2A2. Hence, these two conditions should be considered in the differential diagnosis of OI, especially during the first years of life when other distinctive clinical signs of CIP or FBS are not evident.