Diffuse or focal loss of parafibromin expression as determined by immunohistochemistry was found in the majority of PC, in one-third of atypical adenomas, and very rarely in parathyroid adenomas (8, 9, 10, 11, 12, 13, 19, 20, 21, 22, 23, 24). This evidence concerns the gene CDC73 and parathyroid gland adenoma.