According to the World Health Organization (WHO) (2016), these neoplasms have been divided into three main subgroups based on JAK2/CALR/MPL mutation; that is, Essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF), and four clinicopathologic conditions including chronic myeloid leukemia (CML), chronic neutrophilic leukemia (CNL), chronic eosinophilic leukemia, and unclassifiable (MPN‐U).1, 2, 3, 4, 5, 6. The gene discussed is CALR; the disease is acquired polycythemia vera.