OsteopetrosisOsteopetrosis is an autosomal recessive heredofamilial disorder in which partly calcified cartilaginous intercellular ground substance is not regularly reabsorbed & replaced by regular osteoid tissue & bone. Manifested by : Increased bone density masking the distinction between cortex & medulla, bone within bone appearance (Marble's bone). Brittle bone & easily fracturability Fracture healing satisfactory resulting in skeletal deformities. Myelophthisic anemia Hepatosplenomegaly & presence of immature leukocytes & normoblasts in the peripheral blood. Growth retardation,Macrocephaly. Thickening of cranial foramina & thus causing pressure on optic nerve & optic atrophy. Deafness & blindness Dental problems & osteomyelitis of the mandible. Learning disorder but may have normal intelligence despite hearing & visual loss.