Partial tandem duplication of KMT2A gene in patient afflicted with hypereosinophilic syndrome: A case report.

Eosinophilia is defined as a condition with increased eosinophil cell counts in blood more than the standard value. In this regard, when extensive evaluation fails to reveal the underlying causes of this disease, hypereosinophilic syndrome (HES) diagnosis should be considered. Moreover, it is possible that the mutation of the tyrosine kinase genes, as the most common type of cryptic mutations, is associated with HES syndrome. We report a case of a 47-year-old man who was initially diagnosed with HES by Microscopic examination of bone marrow aspiration and peripheral blood cell analysis. After diagnosis, the patient was administered with cortisone acetate, leading to an initial remission. One month after the initial remission, the disease relapsed, and the patient eventually died. This case report provides the first report of HES, in which a novel variant of partial tandem duplication (PTD) was detected in the KMT2A gene.