Several genes encoding key markers and transcriptional regulators of EMT had significantly lower expression in high-grade HT samples compared to ET samples, such as VIM, SNAI1, SNAI2, ZEB1/2 and TWIST1/2, while genes encoding epithelial cell markers, such as CDH1, EPCAM and CLDN1, had significantly higher expression in high-grade HT samples (Fig. 3d). This evidence concerns the gene CLDN1 and hematocrit.