目的　探讨非肌性肌球蛋白重链9基因相关疾病（MYH9-RD）的基因突变及临床特征。方法　回顾分析同 一家系2例MYH9-RD患者的临床资料，并复习相关文献。结果　先证者（男， 1岁5个月）及其父亲（30岁）均有巨大血小 板、血小板减少和粒细胞内包涵体，先证者之父还存在神经性耳聋，均曾误诊免疫性血小板减少症，接受激素治疗无效。 先证者及其父亲存在MYH9基因c.4270G＞A杂合突变，导致氨基酸改变p.D1424N，为错义突变。国内已报道48个家系 MYH9-RD，38个有基因测序结果，其中c.4270G＞A（p.D1424N）为国内报道最多的MYH9基因突变类型。结论　结合细 胞形态学及基因检测有利于MYH9-RD的早期诊断，c.4270G＞A（p.D1424N）为国内最为常见的MYH9基因突变类型。

Objective　To investigate the genetic mutations and clinical characteristics of nonmuscle myosin heavy chain 9 related diseases (MYH9-RD). Methods　The clinical data of 2 patients with MYH9-RD in the same family were retrospectively analyzed and the relevant literature was reviewed. Results　The proband (male, 17 months) and his father presented with a triad of giant platelets, decreased platelet count and inclusion bodies in neutrophils. The father of the proband also had neuropathic deafness. Both of them had been misdiagnosed of immune thrombocytopenia and had hormone therapy was not effective. Both the proband and his father had heterozygous mutations of MYH9 gene (c.4270G >A), which led to an amino acid change (p.D1424N) and was a missense mutation. In China, 38 have gene sequencing results in 48 reported families of MYH9-RD, among which c.4270G>A (p.D1424N) is the most reported mutation type of MYH9 gene. Conclusions　Combining cell morphology and gene detection is beneficial to the early diagnosis of MYH9-RD, and c.4270G>A (p.D1424N) is the most common MYH9 gene mutation type in China.