Parafibromin is associated with tumor-suppressive properties, as (a) the majority of CDC73 germline mutations in HPT-JT and FIHP kindred as well as the bulk of somatic mutations in sporadic parathyroid carcinomas are disruptive [35, 43, 79–81, 87–89], (b) the majority of tumors with CDC73 mutations exhibit loss of parafibromin expression [57, 89–95], and (c) functional experiments with CDC73 plasmids support an anti-proliferative effect of the wild-type protein [96]. This evidence concerns the gene CDC73 and parathyroid gland carcinoma.