They are commonly found in hematologic myeloid neoplasms, with JAK2V617F as the most common site for JAK2 mutation, which is the most common driver mutation for myeloproliferative neoplasm (MPN) and is present in 95% of patients with polycythemia vera (PV), and 50%–60% of patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF) [2]. The gene discussed is JAK2; the disease is myeloproliferative disorder.