While reactive eosinophilia is induced by eosinopoietic cytokines, such as IL‐5, IL‐3, or GM‐CSF, clonal eosinophilia is typically triggered by rearrangements in certain oncogenic target genes, including PDGFRA, PDGFRB, fibroblast growth factor receptor‐1 (FGFR1), JAK2, ABL1, and ETV6.6, 7, 8, 9, 10, 11, 14, 15, 16, 17. This evidence concerns the gene JAK2 and Increased total eosinophil count.