MYH9 disorder: Identification and a novel mutation in patients with macrothrombocytopenia

Abstract

The diagnosis of MYH9 disorder is guided by recognizing granulocyte Döhle body-like inclusion bodies and large/giant platelets in the peripheral blood smear. Immunofluorescence study of nonmuscle myosin heavy chain IIA is a sensitive screening method for diagnosis of MYH9 disorder. The diagnosis can then be confirmed by genetic analysis. A total of 67 patients with macrothrombocytopenia were included, of which 11 patients (16%), aged 4 months to 22 years, were ultimately diagnosed with MYH9 disorder. One novel mutation in exon 30 at c.4338T>C (p.F1446A) was detected. This mutation was associated with nonhematologic manifestations presenting in late adolescence with cataracts, hearing loss, and hematuria.

Diagnostic delay of MYH9‐related disorder in Japan

“…10 Döhle-like bodies are relatively easy to detect in the coil/tail variant group compared to the head variant group. [19][20][21] This information suggests that detectable Döhle-like bodies in the coil/ tail variants play an important role as a trigger to suspect MYH9-RD. Furthermore, we have previously reported that IPF% can be an adjunctive diagnostic factor, as IPF% is high at any variant site.…”

“…RNA content is responsible for the morphological appearance of conventionally stained blood films and the amount of RNA is decreased in head variants 10 . Döhle‐like bodies are relatively easy to detect in the coil/tail variant group compared to the head variant group 19–21 . This information suggests that detectable Döhle‐like bodies in the coil/tail variants play an important role as a trigger to suspect MYH 9‐RD.…”