Osteopetrosis literally means "stone bone". This hereditary disorder results from defective osteoclasts and overgrowth of bone which makes bones to become sclerotic and thick, but their abnormal structure results in them being both weak and brittle, which increases the likelihood of fractures. The x-ray above shows relatively thickened and dense ribs, humerus and vertebrae. Patients may suffer from anemia, recurrent infections, and hepatosplenomegaly due to bone expansion leading to bone marrow narrowing and extramedullary hematopoiesis.Treatment is with bone marrow transplant and resultant normalisation of bone production.