A very rare dominantly inherited syndrome characterized mainly by increased bone density. The increased bone density results because old bone is not resorbed and replaced with new bone. Only 33 cases in 3 families have been reported. In type I, the increased bone density occurs throughout the body with the skull being the most affected. There is no associated increase in risk of fractures. Many cases are asymptomatic. See also Osteopetrosis autosomal dominant type 1