The S3FB1 mutation is necessary for diagnosis, with or without other myeloid neoplasm-associated mutations or abnormal cytogenetics, but always without BCR-ABL1 translocation or other genetic abnormalities of myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusion [3]. The gene discussed is ABL1; the disease is Increased total eosinophil count.