Th17 cells, secreting IL17, played a crucial role in tumor immune surveillance [22], and was raised after JAK inhibitor treatment in MPN patient, especially in clinically responded patients [23], suggesting genes involving Th17 cell differentiation and IL17 signaling in the ‘tan’ module played a role in immune microenvironment of PV. The gene discussed is IL17A; the disease is acquired polycythemia vera.