Individuals with suspected familial (also called genetic or hereditary) primary hyperparathyroidism, meaning those displaying a non-MEN phenotype with a single manifestation at the parathyroid level, might harbor pathogenic variants of the CDC73 gene [137], CASR (the calcium-sensing receptor), and RET (rearranged during transfection) genes (in MEN2) [138]. Here, CASR is linked to multiple endocrine neoplasia.