OBJECTIVESTo identify the nonmuscle myosin heavy chain 9 (MYH9) gene mutation site in a May-Hegglin anomaly(MHA) patient, and to analyze the genotype of her relatives to exclude the inherit correlation between the proband and her family members.

METHODSInclusion bodies in neutrophils of the proband were examined by transmission electron microscope, and giant platelets by scanning electron microscope. The mutation "hot spot" on the MYH9 gene of the proband and her family members was amplified with polymerase chain reaction(PCR), and then sequenced in both directions to identify the mutant site.

RESULTS(1) The proband manifested with the typical MHA triad of giant platelet, thrombocytopenia and Dohle-like inclusion bodies in neutrophil. However, all of the proband's family members had no such anomaly. (2) Transmission electron microscope and scanning electron microscope confirmed that giant platelets and neutrophils inclusion bodies existed in the proband peripheral blood cells. (3) There was a missense mutation 5797 C-->T in the exon 40 of MYH9 gene which led to Arg changing into termination codon (Arg1933 stop). The proband also had a heterozygous mutation 4876A-->G in exon 33. There was no abnormal finding in the sites mentioned above in her mother, while her father carried the homozygous 4876A-->G mutation.

CONCLUSIONSThis MHA case is a sporadic one, in whose family a mode for autosomal dominant inheritance can not be established. The 5797C-->T substitution in MYH9 gene is a pathogenic mutation, however, 4876A-->G is simply a polymorphism.