Autosomal dominant thrombocytopenia with microthrombocytes: a family study.

A family demonstrating autosomal dominant thrombocytopenia is described. A 28-year-old Malay housewife was found to have a platelet count of 40 x 10(9)/l with a low mean platelet volume (6.8 fl) while being investigated prior to ovarian cystectomy. The bone marrow was consistent with immune thrombocytopenia but she failed to respond to appropriate therapy. Five siblings, one parent and one nephew have easy bruising and platelet counts of 39-82 x 10(9)/l. Platelet aggregation studies excluded a major functional defect. Survival of homologous platelets in the circulation was normal. Familial thrombocytopenias are rare but important to differentiate from the common acquired thrombocytopenias in order to spare the patient unnecessary treatments.