EPAS1 and hereditary pheochromocytoma-paraganglioma: HIF2A mutations may be associated with neuroendocrine tumors with a recent genotype/phenotype study describing the clinical spectrum of HIF2A mediated diseases (n = 66): class 1a (n = 6, sporadic) with pheochromocytoma, paraganglioma, somatostatinoma and erythrocytosis; class 1b (n = 12; 1 familial, 11 sporadic) with pheochromocytoma, paraganglioma and erythrocytosis; class 1c (n = 20; all sporadic) with pheochromocytoma and paraganglioma, and class 2 (n = 28; 9 familial, 6 sporadic) with erythrocytosis alone.