Although there is a strong genotype-phenotype relationship regarding cancer-causing and non-cancer-causing HIF2α mutations, patients presenting with PPGL display a wide range of clinical outcomes, ranging from a single PPGL tumor and no polycythemia to multiple PPGL tumors with polycythemia to PPGL tumors comorbid with both polycythemia and somatostatinoma (Tarade et al., 2018). Here, EPAS1 is linked to polycythemia.