In the rare hereditary bone disorder of osteopetrosis, reduced bone resorption function leads to both the development of densely sclerotic fragile bones and progressive obliteration of the marrow spaces and cranial foramina. Marrow obliteration, typically associated with extramedullary hemopoiesis and hepatosplenomegaly, results in anemia and thrombocytopenia; and nerve entrapment accounts for progressive blindness and hearing loss. Severe infantile or malignant osteopetrosis is the worst type of the disease which has poor prognosis. In this study we report two cases of severe infantile or malignant type of the disease in an Iranian family.

Our two patients were children of a family where the wife is a grandchild of the husband’s aunt. The first patient had episodes of seizure and spastic in extremities 2 weeks after birth. Gradually, the patient showed upper and lower respiratory problems and horizontal nystagmus. X-Ray of hand and foot showed widening and increased bone density and physical examination showed hepatosplenomegallay and petechiae in extremities. The patient expired due to cardiopulmonary arrest. The second patient had also episodes of seizure 2 weeks after birth. Gradually, dissymmetry in eyes appeared and blindness was confirmed by ophthalmologist. Finally the patient expired because of severe pneumonia.

Autosomal recessive osteopetrosis has been reported in most ethnic groups although it is more frequently seen in ethnic groups where consanguinity is common. We report for the first time two cases of severe infantile or malignant type of the disease in an Iranian family.