Osteopetrosis

Thickening of the bones which become abnormally dense due an inherited defect in bone resorption -- the process in which old bone is broken down and removed so that new bone can be added to the skeleton. Osteoclasts are the cells responsible for bone resorption. In osteopetrosis the osteoclasts do not perform normally. This flaw in bone resorption results in bones that are abnormally dense, yet are fragile and easily broken. Men and women are equally affected by the disease.