An autosomal dominant disorder caused by mutation(s) of the MYH9 gene, encoding myosin-9. Clinical features include thrombocytopenia, giant platelets, and characteristic inclusions in peripheral blood leukocytes, and may be associated with other organ dysfunction. It comprises the Epstein syndrome, Fechtner syndrome, May-Hegglin anomaly, and Sebastian syndrome-- all of which were previously believed to be distinct entities. [ ]