OBJECTIVE To explore the molecular basis for a pedigree affected with May-Hegglin anomaly (MHA). METHODS Peripheral blood samples were collected and subjected to DNA extraction. Exons 1, 10, 16, 24, 25, 26, 30, 31, 33, 38 and 40 and flanking sequences of the MYH9 gene were subjected to PCR amplification and Sanger sequencing. Changes in protein expression were determined by an indirect immunofluorescence assay. Platelet aggregation function of the proband was assessed by thromboelastogram. RESULTS The proband and his second son both carried a heterozygous 5521G>A (GAG to AAG) missense variant in exon 38 of the MYH9 gene, leading to p.Glu1841Lys substitution at position 1841 of amino acid sequence. Immunofluorescence showed inclusions containing NMMHC-II A. Thromboelastogram suggested enhanced platelet aggregation function of the proband. CONCLUSIONS The c.5521G>A variant of MYH9 gene has co-segregated with the phenotype of MHA in this pedigree. To assess the aggregation function of platelet by thromboelastogram can predict the risk of bleeding in MHA patients.