SDHB and pheochromocytoma: Pathogenic variants in SDHB and SDHC in particular, have been associated with the development of paragangliomas (PGLs) and pheochromocytomas (PHEOs); these are usually benign catecholamine-secreting tumours that are derived from the chromaffin cells of the adrenal medulla in the case of PGL, and the extra adrenal ganglia in the case of PHEOs [16].