In one study developed by Neumann et al., it was found that 24% of the patients with apparently non-syndromic pheochromocytomas and no family history of the disease had mutations in VHL, RET, SDHD, and SDHB genes; these patients presented at a younger age (average of 24 years), and they had multiple tumors and 28% extra-adrenal tumors (62). Here, SDHB is linked to hereditary pheochromocytoma-paraganglioma.