A Chinese Family with MYH9-RD Caused by MYH9 p.E1841K Mutation Exhibiting Widespread May-Hegglin Inclusions

Xiaoqiang Lian¹Haixia Li²Jihong Hao³Haixin Li¹Ling Xu¹Shuxia Zhang¹Li Cao¹Ruimin Li^1*

• ¹Clinical Laboratory, HanDan Central Hospital, Handan, Hebei Province, China
• ²Anesthesiology, HanDan Central Hospital, Handan, Hebei Province, China
• ³Clinical Laboratory, Second Hospital of Hebei Medical University, Shijiazhuang, Hebei Province, China

MYH9-related disease (MYH9-RD) is a rare autosomal dominant genetic syndrome characterized by congenital thrombocytopenia associated with the risk of developing progressive nephropathy, sensorineural deafness, and presenile cataract. This disorder is often misdiagnosed as immune thrombocytopenic purpura (ITP), particularly in patients presenting with isolated thrombocytopenia. Here, we report the case of a 10-year-old girl initially diagnosed with ITP due to isolated thrombocytopenia and intermittent epistaxis. Further evaluation revealed giant platelets on peripheral blood and bone marrow smears, along with blue inclusions in neutrophils, eosinophils, and monocytes. Family history indicated thrombocytopenia in her mother and maternal grandmother, with her mother also having mild hearing impairment and her grandmother having died of renal failure, both of which are common non-hematological manifestations of MYH9-RD. Genetic testing confirmed the presence of an MYH9 p.E1841K mutation inherited from her mother, leading to a definitive diagnosis of MYH9-RD. This case underscores the importance of considering MYH9-RD in the differential diagnosis of unexplained thrombocytopenia, particularly in the presence of characteristic cytological findings and relevant family history. It also highlights the phenotypic consistency within affected families, emphasizing the necessity of ongoing monitoring and follow-up for relatives carrying the mutation.