We report on 10 JAK2 V617Fpos/BCR::ABL1pos patients in whom both mutations were identified simultaneously in 5/10 (50%) patients or in whom BCR::ABL1 appeared a median of 14 years after the primary diagnosis of JAK2 V617Fpos myeloproliferative neoplasia (MPN) in the remaining 5 patients. The gene discussed is JAK2; the disease is myeloproliferative disorder.