Immunocytochemistry for the heavy chain of the non-muscle myosin IIA as a diagnostic tool for MYH9-related disorders

May-Hegglin anomaly (MHA), Sebastian syndrome (SBS) and Fechtner syndrome (FTNS) are autosomal-dominant macrothrombocytopenias with Dohle-like leucocyte inclusions. These diseases are due to mutations of the MHY9 gene, encoding the heavy chain of non-muscle myosin IIA (NMMHC-A). We investigated the NMMHC-A localization in blood cells from eight MHA, SBS or FTNS patients with known MYH9 mutations. All the patients showed an altered localization of NMMHC-A in granulocytes and platelets, suggesting that Dohle-like bodies are due to the aggregation of NMMHC-A in the cytoplasm. Therefore, immunocytochemistry for NMMHC-A is a simple and sensitive method to detect pathological phenotypes of granulocytes and platelets in the diagnosis of MYH9 -related disorders.