Currently, the May-Hegglin anomaly (MHA), Sebastian (SBS), Fechtner (FTNS) and Epstein (EPS) syndrome are considered to be distinct clinical manifestations of a single disease caused by mutations of the MYH9 gene encoding the heavy chain of non-muscle myosin IIA (NMMHC-IIA). Manifestations of these disorders include giant platelets, thrombocytopenia and combinations of the presence of granulocyte inclusions, deafness, cataracts and renal failure. We examined 15 patients from 10 unrelated families on whom we performed immunostaining of NMMHC-IIA in blood samples. Polymerase chain reaction (PCR) analysis of selected exons of the MYH9 gene revealed mutations in nine samples with one novel mutation. Results of fluorescence and mutational analysis were compared with clinical manifestations of the MYH9 disorder. We also determined the number of glycoprotein sites on the surface of platelets. Most patients had an increased number of glycoproteins, which could be due to platelet size.