MEN1 and tumor of parathyroid gland: The molecular pathogenesis of parathyroid tumors has already been partly elucidated; Heppner and Carling have reported that inactivating somatic mutations of tumor suppressor genes multiple endocrine neoplasia type 1 (MEN1), RET, and HRPT2/CDC73 have been identified in parathyroid tumors [2, 3].