OBJECTIVETo study the changes of platelet in May-Hegglin anomaly (MHA) and the molecular pathogenesis mechanism.

METHODSPeripheral blood was drawn from the MHA proband, her father and her uncle. Platelet count and morphology were examined by automatic blood cell counter and microscopy, respectively. The platelet membrane protein was examined by flow cytometry. Membrane antibodies were determined by ELISA. PCR was used to amplify the exons 25, 31 approximately 32, 38 and 40 of the MYH 9 gene in the MHA patient and her diseased father. Furthermore, PCR products were sequenced, a specific point mutation was identified and inclusions (Dohle's body) in the neutrophil was detected by indirect immunofluorescence technique.

RESULTSIt was proved that in MHA patients, platelet count was higher by cell counter than by microscope (P < 0.01). Giant platelet was 94% but platelet membrane proteins (CD41, CD61, CD42A, CD42b) were in normal range. Membrane antibodies was undetectable. An A5521G mutation (GAG-->AAG) in the exon 38 was found in the proband and her diseased father, resulting in a characteristic change of NMMHC-A1841 (Glutamic acid-->Arginine), which was not found in other members of the family and in normal controls. Spindle-like inclusions with fluorescence were clearly displayed in neutrophil cytoplasm.

CONCLUSIONThe molecular pathogenesis mechanism of May-Hegglin anomaly is the mutation in MYH 9 gene.