[Usefulness of immunofluorescence analysis of neutrophil nonmuscle myosin heavy chain-A for diagnosing in two sisters with May-Hegglin anomaly].

May-Hegglin anomaly (MHA) is a rare autosomal dominant disorder characterized by thrombocytopenia, giant platelets, and unique leukocyte inclusion bodies. The diagnosis of MHA has been made by identifying leukocyte inclusion bodies on May-Giemsa stained blood film, however, it is not always easy to detect these findings. Therefore, patients with MHA are often misdiagnosed and managed as having idiopathic thrombocytopenic purpura. MHA is caused by mutations in the MYH9 gene, which encodes the nonmuscle mysosin heavy chain-A (NMMCH-A). Currently, MHA is definitively diagnosed by immunofluorescence study of leukocyte NMMHC-A localization and MYH9 gene analysis. In this study, we reported two sisters with MHA, who showed consistently decreased platelet counts and giant platelets. However, we could not detect inclusion bodies in their leukocytes. Immunofluorescence analysis of NMMHC-A in leukocytes of both sisters showed abnormal NMMHC-A localization. Furthermore, MYH9 gene analysis of both patients showed heterozygous R116C mutation in exon 26. Based on these findings, the two sisters were diagnosed as having MHA. Immunofluorescence analysis of neutrophil NMMHC-A is useful for diagnosis in patients without leukocyte inclusion bodies who are suspected of having MHA.