Endocrine tumors, paragangliomas, and pheochromocytomas may also be caused by mutations in common oncogenes, in particular the genes encoding the cyclin-dependent kinase inhibitor (p16), transformation related protein 53 (p53), breast cancer associated protein 1 (BAP1), breast cancer 1 and breast cancer 2 (BRCA1 and BRCA2), α-thalassemia/mental retardation syndrome X-linked (ATRX), and lysine (K)-specific methyltransferase 2D (KMT2D). The gene discussed is ATRX; the disease is pheochromocytoma.