Heterozygous inactivating germline mutation of the cell division cycle 73 (CDC73) tumor suppressor gene encoding parafibromin, is the major genetic abnormality and is detectable in about 70% of classically affected kindreds.(128, 129)CDC73 mutations can also be found in 5%–10% of probands presenting with FIHP(125) and, importantly, in 20%–30% of patients with sporadically‐presenting parathyroid carcinoma.(130, 131, 132). This evidence concerns the gene CDC73 and parathyroid gland carcinoma.