[Case of an hemodialysis patient with MYH9 disorders]

A 70-year-old woman was admitted to our hospital for repair of vascular access for maintenance hemodialysis. She had been undergoing the maintenance hemodialysis for 20 years, however, her underlying renal disease had not been identified. The laboratory data on admission revealed marked thrombocytopenia with giant platelets and a Dohle body-like cytoplasmic inclusion body in granulocytes. The same hematological abnormalities were also detected in the peripheral blood smear of her daughter. We suspected hereditary macrothrombocytopenia and performed gene analysis of the MYH9 gene that encodes the nonmuscle myosin heavy chain-II A (NMMHC- II A). Mutational analysis showed the heterozygous mutation, c. 1841 G>A, in exon 38 of the MYH9 gene (E1841 K). We further examined intracellular NMMHC- II A localization in granulocytes by immunofluorescent analysis. The results revealed that one or two NMMHC- II A-positive granules were observed in neutrophils, whereas these granules were not detected in the granulocytes of normal healthy volunteers. From these analyses, we diagnosed her disease as MYH9 disorder, especially as a May-Hegglin abnormality. Thrombocytopenia is sometimes observed in maintenance hemodialysis patients. To avoid inappropriate medical intervention for the thrombocytopenia, MYH9 disorders should be differentiated.