Only somatic mutations associated with paragangliomas/pheochromocytomas have been detected in the HRAS, ATRX, TP53, and KMT2D genes whereas only germline mutations have been identified in the SDHA, SDHC, SDHAF2, FH, KIF1B, and TMEM127 genes. The gene discussed is KMT2D; the disease is hereditary pheochromocytoma-paraganglioma.