Besides the increased expression of Notch1 and its target gene Hes-1 in psoriatic peripheral CD4+ T cells, we also found that both Notch1 and Hes-1 expression were positively correlated with the ratios of Th17/Treg and RORγt/Foxp3, which signifies a direct link between Notch1 and Th17/Treg immune imbalance in PV. The gene discussed is NOTCH1; the disease is acquired polycythemia vera.