Multiple childhood osteosarcomas in an American Indian family with erythroid macrocytosis and skeletal anomalies.

Three of nine children of possibly consanguineous American Indian parents developed typical osteosarcoma in a 2-year period. Etiologic investigations detected limb anomalies and elevated mean corpuscular volumes (98--109 micrometer3) in the surviving tumor patient, several of her sibs, and her father. Limb anomalies included simple clinodactyly with brachymesophalangy, absence of one digital ray of the foot, and bilateral radioulnar synostosis. The red cell macrocytosis was not accompanied by anemia or explained by the usual causes. No unusual environmental exposures were found and screening for possible oncogenic viruses by culture, electron microscopy, and serology was negative. All family members had elevated antibody titers to Epstein-Barr viral antigens. The proband and her father had excessive chromosomal breaks in the bone marrow. This unusual familial pattern of osseous malignancy and malformation and defective erythropoiesis, tentatively called OSLAM syndrome, may represent impaired regulation of bone development.