Indeed, the molecular background underlying progression is still largely unexplored even though ASXL1, IDH1/2, SRSF2, and TP53 mutations, together with adverse karyotypic changes, place the patient at high risk of leukemic transformation.<h4>Case presentation</h4>Our patient, a 64-year old man with a diagnosis of JAK2 (V617F) primary myelofibrosis (PMF) had an unusually rapid leukemic transformation. The gene discussed is ASXL1; the disease is primary myelofibrosis.