Autosomal dominant osteopetrosis.

Autosomal dominant osteopetrosis is radiographically characterized by universal osteosclerosis, primarily involving the axial skeleton, and by symmetrical affections of the long bones without modeling defects. Based on standard radiographs, it is possible to describe two different subtypes with different clinical, biochemical, and histologic manifestations. Type I is radiographically characterized by pronounced osteosclerosis of the cranial vault, whereas Type II has end-plate thickening of the vertebrae (Rugger-Jersey spine) and endobones in the pelvis. Both types are strictly family related and seen in childhood. Combined radiogrammetric, biochemical, and histologic investigations indicate states of defective bone resorption, whereas bone formation seems to be normal in both types of patients. Patients with autosomal dominant osteopetrosis are often asymptomatic, and the diagnosis may be reached by chance. However, by systematic investigations, nearly all patients have manifestations related to the disorder. Symptoms are progressive with age, and correlated with osteosclerosis. The fracture frequency is increased in Type II patients, and normal in Type I, where biomechanical investigations have shown normal, or even increased trabecular bone strength. Treatment has been symptomatic. A rational treatment consists of stimulation of bone resorption, in combination with inhibition of bone formation if possible.