Hereditary pHPT may be associated to other endocrine or non-endocrine neoplasms, as a part of syndromic disease, as occurs in case of multiple endocrine neoplasia (MEN) type 1, 2 A or 4 and hyperparathyroidism-jaw tumor (HPT-JT) Syndrome (caused by mutations in MEN1, RET, CDKN, CDC73 genes, respectively), or as familial isolated hyperparathyroidism (FIHPT), without any association with further syndromic features [1–3]. The gene discussed is RET; the disease is familial isolated hyperparathyroidism.