The rates of loss of parafibromin expression were 0.522 (95% CI: 0.444-0.599), 0.291 (95% CI: 0.207-0.391), 0.027 (95% CI: 0.011-0.064), and 0.032 (95% CI: 0.008-0.119) in PC, atypical parathyroid adenoma (APA), parathyroid adenoma (PA), and parathyroid hyperplasia, respectively.
No CDC73 LOH was found in PC tissue, nor any differences in expression levels for CDC73 gene, miR-155 and miR-664 between PC and parathyroid adenoma control tissues.
Thus, cell division cycle 73 (CDC73) germline mutations cause HPT-JT, and CDC73 mutations occur in 70% of sporadic PC, but in only ∼2% of parathyroid adenomas.
We present three siblings with familial isolated hyperparathyroidism due to solitary parathyroid adenoma and favorable evolution post-parathyroidectomy.Genetic tests revealed HRPT2 mutation.
However, proponents have found immunohistochemistry for parafibromin useful to definitively confirm a pathological diagnosis of parathyroid carcinoma, predict a worse outcome in definite parathyroid carcinomas, triage formal genetic testing for HPT-JT syndrome, and predict the outcome of histologically atypical parathyroid adenomas.
Gross deletion analysis of the HRPT2 gene is indicated for all patients negative for mutation, presenting with HPT-JT or familial isolated hyperparathyroidism, parathyroid carcinoma, or in patients with apparently sporadic parathyroid adenoma diagnosed at a young age, having a severe hypercalcemia.
Our data could suggest that CDC73-mutated parathyroid adenomas exhibit a partly unique cytogenetic profile in addition to that of carcinomas and unselected adenomas.
The purpose of this study was to investigate the underlying HRPT2 defect in a young patient with symptomatic hyperparathyroidism due to an apparently sporadic parathyroid adenoma with cystic features.
Genetic analysis of tumor samples demonstrated a second somatic CDC73 mutation only in a parathyroid adenoma and no cases with the loss of the wild-type allele or methylation of the CDC73 promoter, even though immunohistochemical analysis demonstrated the loss of nuclear parafibromin expression in all tumors, including a uterine polyp.
In this study, 46 cases of cystic parathyroid adenomas previously investigated for HRPT2 mutations were characterized with regard to MEN1 gene mutations, cyclin D1 expression and parafibromin expression.
Recently, the candidate tumor suppressor gene HRPT2 was identified and alterations in this gene were related with the Hyperparathyroidism-jaw tumor syndrome that is characterized by parathyroid adenoma or carcinoma, fibro-osseous lesions (mainly OF) of the jaws, and renal lesions.
Our observations encourage additional study of the diagnostic potential of HRPT2 in parathyroid neoplasia and support the view that HRPT2 inactivation is not an important participant in the pathogenesis of typical parathyroid adenomas.
The proposed role of HRPT2 as a tumor suppressor was supported by mutation screening in 48 parathyroid adenomas with cystic features, which identified three somatic inactivating mutations, all located in exon 1.
Recurrent mutations in the MEN1 gene have been confirmed by the whole-exome sequencing in 35% of PAs, suggesting that non-protein-coding genes, regulatory elements or epigenetic derangements may also have roles in the majority of PAs.