<b>Background</b>: Multiple endocrine neoplasia type 2A (MEN2A) is a rare, hereditary syndrome resulting from a germline mutation in the <i>RET</i> proto-oncogene and characterized primarily by medullary thyroid cancer (MTC), pheochromocytoma (PHEO), and hyperparathyroidism. This evidence concerns the gene RET and hyperparathyroidism.