Autosomal recessive osteopetrosis.

Osteopetrosis is a genetic disease that is relatively common in Saudi Arabia because of the high rate of consanguineous marriages. It is thought to be due to a lysosomal defect of the osteoclast. It is characterized by marked increase in bone density, frequent fractures and cranial nerve palsies. It is transmitted as an autosomal recessive or autosomal dominant. The autosomal recessive type is common in children and has three forms: severe (malignant), mild (intermediate), and the one associated with cerebral calcification and renal tubular acidosis. Bone marrow transplantation is the treatment of choice for the severe (malignant) type.