TMEM127 is a tumor suppressor gene initially identified as a pheochromocytoma susceptibility gene [37] and later also associated with the development of paragangliomas of head and neck and extra-adrenal abdominal paragangliomas [126–130]. TMEM127 gene encodes a highly conserved transmembrane protein, transmembrane protein 127, which is associated with several cellular organelles and thought to limit mTORC1 activation thus controlling protein synthesis and cell survival [37]. This evidence concerns the gene TMEM127 and pheochromocytoma.