MEN1 and multiple endocrine neoplasia type 1: Germline genetic alterations in MEN1 (multiple endocrine neoplasia type 1) gene are associated with PHPT in the context of MEN1 syndrome, and mutations in HRPT2 (hyperparathyroidism 2) gene are associated with HPT-JT (Hyperparathyroidism-Jaw tumor) familial syndrome.