Complex II mutations, principally affecting SDHB and SDHD subunits, have been associated with various cancers including hereditary paraganglioma and pheochromocytoma (i.e., neuroendocrine tumors of the paraganglionic tissue), gastrointestinal stromal tumors [60], and renal cell carcinoma [61]. This evidence concerns the gene SDHB and hereditary pheochromocytoma-paraganglioma.