The first RET pathogenic variants were reported in 1993 by two independent groups [7,8], and since then, more than 100 pathogenic RET variants have also been identified in a large percentage of MEN2A patients who were clinically diagnosed with MTC, pheochromocytoma, or both [6,9,10]. This evidence concerns the gene RET and hereditary pheochromocytoma-paraganglioma.