The complexity of hereditary forms of PHPT was reflected by a 28-year-old male who developed asymptomatic PHPT, multifocal MTC, and bilateral PC in the setting of two pathogenic variants of the RET gene (Cys630Tyr) and of the MEN1 gene (p.Ala176Leufs*10) [139]. This evidence concerns the gene RET and medullary thyroid gland carcinoma.