A fatal myeloproliferative syndrome in a family with thrombocytopenia and platelet dysfunction.

Three siblings with a lifelong history of a bleeding disorder and thrombocytopenia died from a myeloproliferative disease. In 2, the terminal event resembled juvenile chronic myelogenous leukemia, and in the third, the diagnosis was acute monocytic leukemia. A family study revealed that the mother and 5 other siblings had a variety of hematologic abnormalities. These included chronic thrombocytopenia, abnormal platelet function, elevated concentrations of HgbF or serum vitamin B12, and low leukocyte alkaline phosphatase (LAP) scores either singly or in combination. At the time of study, none had evidence of malignancy. Members of this family have a myeloproliferative disorder that has the potential for terminating in nonlymphocytic leukemia, a combination of events which appears not to have been reported previously.