In addition to Th2 cells, Th2 cytokine levels are significantly higher in the serum of patients with PV than controls, suggesting an imbalance between Dsg3-reactive Th2 and Th1 cells in the pathogenesis of PV (Satyam et al., 2009; Lee et al., 2017). The gene discussed is DSG3; the disease is acquired polycythemia vera.