JAK2 and acquired polycythemia vera: A somatic point mutation (c.1849G>T) in the JAK2 gene, part of the JAK2-STAT signal-transduction pathway, causes substitution of phenylalanine for valine (V617F) in the JAK2 protein and has been identified in Ph-neg MPNs especially in polycythemia vera (PV) [1–5].