HRPT2

Gene Summary

Gene:HRPT2; hyperparathyroidism 2 (with jaw tumor)
Aliases: HPT-JT
Location:1q21-q31
Summary:-
Databases:OMIM, HGNC, GeneCard, Gene
Source:NCBIAccessed: 06 August, 2015

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 06 August 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Parathyroid Hormone
  • Uterine Cancer
  • Multiple Endocrine Neoplasia Type 1
  • Adolescents
  • Receptors, Calcium-Sensing
  • Childhood Cancer
  • Chromosome 1
  • Tumor Markers
  • Jaw Neoplasms
  • Germ-Line Mutation
  • Genetic Testing
  • Genetic Predisposition
  • DNA Methylation
  • Base Sequence
  • DNA Mutational Analysis
  • Molecular Sequence Data
  • Immunohistochemistry
  • Loss of Heterozygosity
  • Hyperparathyroidism, Primary
  • Cyclin D1
  • Carcinoma
  • Tumor Suppressor Gene
  • Proto-Oncogene Proteins
  • Young Adult
  • Cancer Gene Expression Regulation
  • Adenoma
  • Proteins
  • Parathyroid Cancer
  • Cancer DNA
  • Mutation
  • RTPCR
  • Multiple Endocrine Neoplasia Type 2a
  • Parathyroidectomy
  • Hyperparathyroidism
  • Parathyroid Glands
  • Up-Regulation
  • Fibroma, Ossifying
  • Pedigree
  • Tumor Suppressor Proteins
Tag cloud generated 06 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: HRPT2 (cancer-related)

Parfitt J, Harris M, Wright JM, Kalamchi S
Tumor suppressor gene mutation in a patient with a history of hyperparathyroidism-jaw tumor syndrome and healed generalized osteitis fibrosa cystica: a case report and genetic pathophysiology review.
J Oral Maxillofac Surg. 2015; 73(1):194.e1-9 [PubMed] Related Publications
Hyperparathyroidism-jaw tumor (HPT-JT) was first observed by Jackson in 1958 in a family who exhibited hyperparathyroidism and recurrent pancreatitis. The author noticed the presence of jaw tumors in the affected family and reported them as fibrous dysplasia. However, it was not until 1990 that a familial variety of hyperparathyroidism with fibro-osseous jaw tumors was recognized as HPT-JT syndrome and reported as a clinically and genetically distinct syndrome. Hyperparathyroidism generally arises from glandular hyperplasia or parathyroid adenomas, with only about 1% of cases resulting from parathyroid carcinoma. However, parathyroid carcinoma develops in about 15% of HPT-JT patients. The true incidence of HPT-JT is unknown, although the prevalence of about 100 published cases suggests its rarity. Twenty percent of HPT-JT cases have renal hamartomas or tumors, and female patients with HPT-JT have been reported to have carcinoma of the uterus. This syndrome appears to arise from a variety of mutations that deactivate the tumor suppressor gene CDC73 (also known as HRPT2) and its production of the tumor suppressor protein parafibromin. Functional parafibromin has 531 amino acids, and mutations result in a short nonfunctional protein. CDC73 disorders exhibit dominant germline gene behavior, with varying degrees of penetration. In most cases an affected person has 1 parent with the condition, which raises the need for family investigation and genetic counseling. We report a case of HPT-JT syndrome in a male patient who presented to the local community hospital 6 years previously with a history of back pain. Investigations showed elevated serum parathyroid hormone and calcium levels, and a technetium 99m sestamibi parathyroid scan showed increased activity at the site of the lower left gland that proved to be a substernal parathyroid carcinoma. The patient's parathyroid hormone level dropped from 126 to 97 pg/mL at 5 minutes and was 65 pg/mL at 10 minutes after excision of the gland, and the calcium chemistry findings returned to normal. Parathyroid histologic analysis showed substantial cytologic atypia with nuclear pleomorphism and prominent nucleoli, but infrequent mitoses. Although the capsule was described as showing foci of vascular invasion by the carcinoma, there has been no evidence of recurrence. Six years later, the patient presented with bilateral mandibular cemento-ossifying fibromas, but no evidence of hyperparathyroidism. The larger left tumor was excised and immediately reconstructed with an autogenous iliac crest bone graft, and the right lesion was enucleated. There has been no recurrence in 12 months. This case illustrates that the hyperparathyroidism and the fibro-osseous tumors are independent features of the persistent germline tumor suppressor gene (CDC73) mutation. The syndromic fibro-osseous tumors are odontogenic cemento-ossifying fibromas, which only occur in the jaws.

Mehta A, Patel D, Rosenberg A, et al.
Hyperparathyroidism-jaw tumor syndrome: Results of operative management.
Surgery. 2014; 156(6):1315-24; discussion 1324-5 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
BACKGROUND: Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is a rare, autosomal-dominant disease secondary to germline-inactivating mutations of the tumor suppressor gene HRPT2/CDC73. The aim of the present study was to determine the optimal operative approach to parathyroid disease in patients with HPT-JT.
METHODS: A retrospective analysis of clinical and genetic features, parathyroid operative outcomes, and disease outcomes in 7 unrelated HPT-JT families.
RESULTS: Seven families had 5 distinct germline HRPT2/CDC73 mutations. Sixteen affected family members (median age, 30.7 years) were diagnosed with primary hyperparathyroidism (PHPT). Fifteen of the 16 patients underwent preoperative tumor localization studies and uncomplicated bilateral neck exploration at initial operation; all were in biochemical remission at most recent follow-up. Of these patients, 31% had multiglandular involvement; 37.5% of the patients developed parathyroid carcinoma (median overall survival, 8.9 years; median follow-up, 7.4 years). Long-term follow-up showed that 20% of patients had recurrent PHPT.
CONCLUSION: Given the high risk of malignancy and multiglandular involvement in our cohort, we recommend bilateral neck exploration and en bloc resection of parathyroid tumors suspicious for cancer and life-long postoperative follow-up.

Chiofalo MG, Sparaneo A, Chetta M, et al.
A novel CDC73 gene mutation in an Italian family with hyperparathyroidism-jaw tumour (HPT-JT) syndrome.
Cell Oncol (Dordr). 2014; 37(4):281-8 [PubMed] Related Publications
PURPOSE: The CDC73 gene, encoding parafibromin, has been identified as a tumour suppressor gene both in hyperparathyroidism-jaw tumour (HPT-JT) syndrome and in sporadic parathyroid carcinoma. While the vast majority of CDC73 mutations affect the N-terminus or the central core of the encoded protein, as yet few mutations have been reported affecting the C-terminus. Here, we report a case (Caucasian female, 28 years) with an invasive ossifying fibroma of the left mandible and hyperparathyroidism (sCa = 16 mg/dl, PTH = 660 pg/mL) due to a parathyroid lesion of 20 mm, hystologically diagnosed as carcinoma.
METHODS: The whole CDC73 gene was screened for the presence of mutations by Sanger sequencing. Immunohistochemistry, in vitro functional assays, Western blotting, MTT assays and in-silico modelling were performed to assess the effect of the detected mutation.
RESULTS: Sequence analysis of the CDC73 gene in the proband revealed the presence of a novel deletion affecting the C-terminus of the encoded protein (c.1379delT/p.L460Lfs*18). Clinical and genetic analyses of the available relatives led to the identification of three additional carriers, one of whom was also affected by a parathyroid lesion. Immunohistochemistry, Western blotting, MTT and in-silico modelling assays revealed that the deletion leads to down-regulation of the mutated protein, most likely through a proteasome-mediated pathway. We also found that the deletion may cause a conformational change in the C-terminus of the protein, possibly affecting its interaction with partner proteins. Finally, we found that the mutant protein enhances cellular growth.
CONCLUSIONS: We report a novel mutation in the CDC73 gene that may underlie HPT-JT syndrome. This mutation appears to affect the C-terminal moiety of the encoded protein, which is thought to interact with other protein partners. The identification of these partners may be instrumental for our understanding of the CDC73-associated phenotype.

Lee JY, Kim SY, Mo EY, et al.
Upregulation of FGFR1 expression is associated with parathyroid carcinogenesis in HPT-JT syndrome due to an HRPT2 splicing mutation.
Int J Oncol. 2014; 45(2):641-50 [PubMed] Related Publications
Mutations of the HRPT2 gene, which are responsible for hyperparathyroidism-jaw tumor (HPT-JT) syndrome, have been implicated in the development of a high proportion of parathyroid carcinomas. The aim of this study was to investigate differences in expression of the most important genes connected with parathyroid carcinoma between HPT-JT syndrome due to an HRPT2 splicing mutation, normal parathyroid tissue and sporadic parathyroid adenoma. Total RNAs were extracted from parathyroid carcinoma in HPT-JT syndrome harbouring HRPT2 splicing mutation or sporadic parathyroid adenoma and normal parathyroid gland, and subjected to Illumina DASL-based gene expression assay. Unsupervised hierarchical clustering analysis was used to compare gene expression in HPT-JT syndrome, sporadic parathyroid adenoma and normal parathyroid glands. We identified differentially regulated genes in HPT-JT syndrome and sporadic parathyroid adenoma relative to normal parathyroid glands using a combination of Welch's t-test and fold-change analysis. Quantitative PCR, RT-PCR and IHC were used for validation. Sixteen genes differentially regulated in the parathyroid carcinoma were associated with signal pathways, MAPK, regulation of actin cytoskeleton, prostate cancer and apoptosis. FGFR1 expression was confirmed to be significantly upregulated by validation experiments. Our gene expression profiling experiments suggest that upregulated FGFR1 expression appears to be associated with parathyroid carcinoma in HPT-JT syndrome due to an HRPT2 splicing mutation.

Korpi-Hyövälti E, Cranston T, Ryhänen E, et al.
CDC73 intragenic deletion in familial primary hyperparathyroidism associated with parathyroid carcinoma.
J Clin Endocrinol Metab. 2014; 99(9):3044-8 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
CONTEXT: CDC73 mutations frequently underlie the hyperparathyroidism-jaw tumor syndrome, familial isolated hyperparathyroidism (FIHP), and parathyroid carcinoma. It has also been suggested that CDC73 deletion analysis should be performed in those patients without CDC73 mutations.
OBJECTIVE: To investigate for CDC73 deletion in a family with FIHP previously reported not to have CDC73 mutations.
PATIENTS AND METHODS: Eleven members (six affected with primary hyperparathyroidism and five unaffected) were ascertained from the family, and multiplex ligation-dependent probe amplification was performed to detect CDC73 deletion using leukocyte DNA.
RESULTS: A previously unreported deletion of CDC73 involving exons 1-10 was detected in five affected members and two unaffected members who were 26 and 39 years of age. Two affected members had parathyroid carcinomas at the ages of 18 and 32 years, and they had Ki-67 proliferation indices of 5 and 14.5% and did not express parafibromin, encoded by CDC73. Primary hyperparathyroidism in the other affected members was due to adenomas and atypical adenomas, and none had jaw tumors. Two affected members had thoracic aortic aneurysms, which in one member occurred with parathyroid carcinoma and renal cysts.
CONCLUSION: A previously unreported intragenic deletion of exons 1 to 10 of CDC73 was detected in a three-generation family with FIHP, due to adenomas, atypical adenomas, and parathyroid carcinomas. In addition, two affected males had thoracic aortic aneurysms, which may represent another associated clinical feature of this disorder.

Kong J, Wang O, Nie M, et al.
Familial isolated primary hyperparathyroidism/hyperparathyroidism-jaw tumour syndrome caused by germline gross deletion or point mutations of CDC73 gene in Chinese.
Clin Endocrinol (Oxf). 2014; 81(2):222-30 [PubMed] Related Publications
OBJECTIVE: Hyperparathyroidism-jaw tumour syndrome (HPT-JT) and familial isolated primary hyperparathyroidism (FIHP) are two subtypes of familial primary hyperparathyroidism, which are rarely reported in Chinese population. Here, we reported three FIHP families and one HPT-JT family with long-term follow-up and genetic analysis.
DESIGN AND METHODS: A total of 22 patients, from four FIHP/HPT-JT families of Chinese descent, were recruited and genomic DNA was extracted from their peripheral blood lymphocytes. Direct sequencing for MEN1, CDC73, CASR gene was conducted. Reverse transcription PCR (RT-PCR) and quantitative real-time PCR (qRT-PCR) were used to study the effect of splice site mutations and gross deletion mutations. Immunohistochemistry was performed to analyse parafibromin expression in parathyroid tumours. Genotype-phenotype correlations were assessed through clinical characteristics and long-term follow-up data.
RESULTS: Genetic analysis revealed four CDC73 germline mutations that were responsible for the four kindreds, including two novel point mutation (c.157 G>T and IVS3+1 G>A), one recurrent point mutation (c.664 C>T) and one deletion mutation (c.307+?_513-?del exons 4, 5, 6). RT-PCR confirmed that IVS3+1 G>A generated an aberrant transcript with exon3 deletion. Immunohistochemical analysis demonstrated reduced nuclear parafibromin expression in tumours supporting the pathogenic effects of these mutations.
CONCLUSIONS: This study supplies information on mutations and phenotypes of HPT-JT/FIHP syndrome in Chinese. Screening for gross deletion and point mutations of the CDC73 gene is necessary in susceptible subjects.

Pazienza V, la Torre A, Baorda F, et al.
Identification and functional characterization of three NoLS (nucleolar localisation signals) mutations of the CDC73 gene.
PLoS One. 2013; 8(12):e82292 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Hyperparathyroidism Jaw-Tumour Syndrome (HPT-JT) is characterized by primary hyperparathyroidism (PHPT), maxillary/mandible ossifying fibromas and by parathyroid carcinoma in 15% of cases. Inactivating mutations of the tumour suppressor CDC73/HRPT2 gene have been found in HPT-JT patients and also as genetic determinants of sporadic parathyroid carcinoma/atypical adenomas and, rarely, typical adenomas, in familial PHPT. Here we report the genetic and molecular analysis of the CDC73/HRPT2 gene in three patients affected by PHPT due to atypical and typical parathyroid adenomas, in one case belonging to familial PHPT. Flag-tagged WT and mutant CDC73/HRPT2 proteins were transiently transfected in HEK293 cells and functional assays were performed in order to investigate the effect of the variants on the whole protein expression, nuclear localization and cell overgrowth induction. We identified four CDC73/HRPT2 gene mutations, three germline (c.679_680delAG, p.Val85_Val86del and p.Glu81_Pro84del), one somatic (p.Arg77Pro). In three cases the mutation was located within the Nucleolar Localisation Signals (NoLS). The three NoLS variants led to instability either of the corresponding mutated protein or mRNA or both. When transfected in HEK293 cells, NoLS mutated proteins mislocalized with a predeliction for cytoplasmic or nucleo-cytoplasmic localization and, finally, they resulted in overgrowth, consistent with a dominant negative interfering effect in the presence of the endogenous protein.

Rather MI, Swamy S, Gopinath KS, Kumar A
Transcriptional repression of tumor suppressor CDC73, encoding an RNA polymerase II interactor, by Wilms tumor 1 protein (WT1) promotes cell proliferation: implication for cancer therapeutics.
J Biol Chem. 2014; 289(2):968-76 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
The Wilms tumor 1 gene (WT1) can either repress or induce the expression of genes. Inconsistent with its tumor suppressor role, elevated WT1 levels have been observed in leukemia and solid tumors. WT1 has also been suggested to act as an oncogene by inducing the expression of MYC and BCL-2. However, these are only the correlational studies, and no functional study has been performed to date. Consistent with its tumor suppressor role, CDC73 binds to RNA polymerase II as part of a PAF1 transcriptional regulatory complex and causes transcriptional repression of oncogenes MYC and CCND1. It also represses β-catenin-mediated transcription. Based on the reduced level of CDC73 in oral squamous cell carcinoma (OSCC) samples in the absence of loss-of-heterozygosity, promoter methylation, and mutations, we speculated that an inhibitory transcription factor is regulating its expression. The bioinformatics analysis predicted WT1 as an inhibitory transcription factor to regulate the CDC73 level. Our results showed that overexpression of WT1 decreased CDC73 levels and promoted proliferation of OSCC cells. ChIP and EMSA results demonstrated binding of WT1 to the CDC73 promoter. The 5-azacytidine treatment of OSCC cells led to an up-regulation of WT1 with a concomitant down-regulation of CDC73, further suggesting regulation of CDC73 by WT1. Exogenous CDC73 attenuated the protumorigenic activity of WT1 by apoptosis induction. An inverse correlation between expression levels of CDC73 and WT1 was observed in OSCC samples. These observations indicated that WT1 functions as an oncogene by repressing the expression of CDC73 in OSCC. We suggest that targeting WT1 could be a therapeutic strategy for cancer, including OSCC.

Costa-Guda J, Arnold A
Genetic and epigenetic changes in sporadic endocrine tumors: parathyroid tumors.
Mol Cell Endocrinol. 2014; 386(1-2):46-54 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Parathyroid neoplasia is most commonly due to benign parathyroid adenoma but rarely can be caused by malignant parathyroid carcinoma. Evidence suggests that parathyroid carcinomas rarely, if ever, evolve through an identifiable benign intermediate, with the notable exception of carcinomas associated with the familial hyperparathyroidism-jaw tumor syndrome. Several genes have been directly implicated in the pathogenesis of typical sporadic parathyroid adenoma; somatic mutations in the MEN1 tumor suppressor gene are the most frequent finding, and alterations in the cyclin D1/PRAD1 oncogene are also firmly established molecular drivers of sporadic adenomas. In addition, good evidence supports mutation in the CDKN1B/p27 cyclin-dependent kinase inhibitor (CDKI) gene, and in other CDKI genes as contributing to disease pathogenesis in this context. Somatic defects in additional genes, including β-catenin, POT1 and EZH2 may contribute to parathyroid adenoma formation but, for most, their ability to drive parathyroid tumorigenesis remains to be demonstrated experimentally. Further, genetic predisposition to sporadic presentations of parathyroid adenoma appears be conferred by rare, and probably low-penetrance, germline variants in CDKI genes and, perhaps, in other genes such as CASR and AIP. The HRPT2 tumor suppressor gene is commonly mutated in parathyroid carcinoma.

Zhao S, Sun HZ, Zhu ST, et al.
Effects of parafibromin expression on the phenotypes and relevant mechanisms in the DLD-1 colon carcinoma cell line.
Asian Pac J Cancer Prev. 2013; 14(7):4249-54 [PubMed] Related Publications
BACKGROUND: Parafibromin is a protein encoded by the HRPT2 (hyperparathyroidism 2) oncosuppressor gene and its down-regulated expression is involved in pathogenesis of parathyroid, breast, gastric and colorectal carcinomas. This study aimed to clarify the effects of parafibromin expression on the phenotypes and relevant mechanisms of DLD-1 colon carcinoma cells.
METHODS: DLD-1 cells transfected with a parafibromin-expressing plasmid were subjected to examination of phenotype, including proliferation, differentiation, apoptosis, migration and invasion. Phenotype-related proteins were measured by Western blot. Parafibromin and ki-67 expression was detected by immunohistochemistry on tissue microarrays.
RESULTS: The transfectants showed higher proliferation by CCK-8, better differentiation by electron microscopy and ALP activity and more apoptotic resistance to cisplatin by DNA fragmentation than controls. There was no difference in early apoptosis by annexin V, capase-3 activity, migration and invasion between DLD-1 cells and their transfectants. Ectopic parafibromin expression resulted in down-regulated expression of smad4, MEKK, GRP94, GRP78, GSK3β-ser9, and Caspase-9. However, no difference was detectable in caspase-12 and -8 expression. A positive relationship was noted between parafibromin and ki-67 expression in colorectal carcinoma.
CONCLUSIONS: Parafibromin overexpression could promote cell proliferation, apoptotic resistance, and differentiation of DLD-1 cells.

Muntean AG, Chen W, Jones M, et al.
MLL fusion protein-driven AML is selectively inhibited by targeted disruption of the MLL-PAFc interaction.
Blood. 2013; 122(11):1914-22 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
MLL rearrangements are common in leukemia and considered an adverse risk factor. Through interactions with the polymerase-associated factor complex (PAFc), mixed lineage leukemia (MLL) fusion proteins activate genes critical for blocking differentiation, such as HOXA9. Here we investigate whether the MLL-PAFc interaction can be exploited therapeutically using both genetic and biochemical approaches. We tested the genetic requirement of the PAFc in acute myeloid leukemia (AML) using a conditional allele of the PAFc subunit, Cdc73. We show that the PAFc is indiscriminately necessary for the proliferation of AML cells through the epigenetic regulation of proleukemogenic target genes, such as MEIS1 and Bcl2. To investigate the therapeutic potential of targeting the MLL-PAFc interaction, we engineered a dominant negative fragment of MLL capable of binding to the PAFc. Disruption of the MLL-PAFc interaction selectively inhibits the proliferation of MLL leukemic cells without affecting cells transformed by an unrelated E2A-HLF fusion protein. Using in vivo hematopoietic reconstitution assays, we demonstrate that disruption of the MLL-PAFc does not alter normal hematopoietic stem cell function. Together, our data show a selective growth inhibition of MLL-associated leukemic cells and tolerance of normal hematopoiesis to disruption of the MLL-PAFc interaction establishing the MLL-PAFc interaction as an attractive therapeutic target.

Sulaiman L, Juhlin CC, Nilsson IL, et al.
Global and gene-specific promoter methylation analysis in primary hyperparathyroidism.
Epigenetics. 2013; 8(6):646-55 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Epigenetic mechanisms involved in primary hyperparathyroidism are poorly understood as studies are limited. In order to understand the role of aberrant DNA promoter methylation in the pathogenesis of parathyroid tumors, we have quantified the CpG island promoter methylation density of several candidate genes including APC (promoter 1A and 1B), β-catenin (CTNNB1), CASR, CDC73/HRPT2, MEN1, P16 (CDKN2A), PAX1, RASSF1A, SFRP1 and VDR in 72 parathyroid tumors and 3 normal parathyroid references using bisulfite pyrosequencing. Global methylation levels were assessed for LINE-1. We also compared methylation levels with gene expression levels measured by qRT-PCR for genes showing frequent hypermethylation. The adenomas displayed frequent hypermethylation of APC 1A (37/66; 56%), RASSF1A (34/66; 52%) and β-catenin (19/66; 29%). One of the three atypical adenomas was hypermethylated for APC 1A. The three carcinomas were hypermethylated for RASSF1A and SFRP1, and the latter was only observed in this subtype. The global methylation density was similar in tumors (mean 70%) and parathyroid reference samples (mean 70%). In general, hypermethylated genes had reduced expression in the parathyroid adenomas using qRT-PCR. Among the adenomas, methylation of APC 1A correlated with adenoma weight (r = 0.306, p < 0.05). Furthermore, the methylation status of RASSF1A correlated with each of APC 1A (r = 0.289, p < 0.05) and β-catenin (r = 0.315, p < 0.01). Our findings suggest a role for aberrant DNA promoter methylation of APC 1A, β-catenin and RASSF1A in a subset of parathyroid tumors.

Abdulla AG, O'Leary EM, Isorena JP, et al.
Recurrent hyperparathyroidism and a novel nonsense mutation in a patient with hyperparathyriodism-jaw tumor syndrome.
Endocr Pract. 2013 Nov-Dec; 19(6):e134-7 [PubMed] Related Publications
OBJECTIVE: To present the case of a hyperparathyroidism-jaw tumor (HPT-JT) patient with a novel nonsense mutation of the CDC73 gene.
METHODS: We present the case of a patient with a history of three prior maxillectomies and two prior parathyroidectomies who presented with recurrent primary hyperparathyroidism (PHPT). We also briefly review the literature pertaining to HPT-JT.
RESULTS: Genetic analysis revealed a novel nonsense mutation (c.85G>T; pGlu29) in exon 1 of CDC73. The patient's son underwent genetic testing for a CDC73 mutation and was found to be negative.
CONCLUSION: HPT-JT is a rare condition characterized by PHPT and benign tumors of the mandible and maxilla. Up to 15% of HPT-JT patients with PHPT have parathyroid carcinoma. HPT-JT is associated with an inactivating mutation of CDC73, a gene that codes for the tumor suppressor protein parafibromin. This report expands our understanding of the genetics underlying this rare disorder and emphasizes the importance of early detection in order to prevent hypercalcemic complications such as parathyroid carcinoma.

Hendy GN, Cole DE
Genetic defects associated with familial and sporadic hyperparathyroidism.
Front Horm Res. 2013; 41:149-65 [PubMed] Related Publications
Primary hyperparathyroidism (PHPT) occurs sporadically, but occasionally it may be a feature of a familial condition, such as multiple endocrine neoplasia type 1 (MEN1), MEN2A, or the HPT-jaw tumor syndrome (HPT-JT), and familial hypocalciuric hypercalcemia/neonatal severe hyperparathyroidism (FHH/NSHPT). PHPT may also occur as familial isolated hyperparathyroidism (FIHP), and has been observed as a consequence of mutations in the CDKN1B gene (MEN4). Tumorigenesis in these conditions may be the result of protooncogene activation (e.g. RET in MEN2) or two-hit losses of a tumor suppressor (e.g. MEN1, HPT-JT). In patients with MEN1, HPT-JT or FHH/NSHPT, the hyperparathyroidism manifests at a younger age and affects both sexes equally. In MEN1, mutations of the MEN1 gene also cause enteropancreatic and anterior pituitary tumors. In MEN2, activating mutations in the RET protooncogene also cause medullary thyroid carcinoma and pheochromocytoma. In HPT-JT, mutations of CDC73/HRPT2 are associated with parathyroid carcinoma, but tumors of the kidneys and uterus are additional features. In some FIHP families, a CASR mutation may be identified. In parathyroid carcinoma, even if sporadic, molecular diagnostics for CDC73/HRPT2 should be considered, as it should be for younger patients. Further exploration of these hereditary syndromes may shed light on the molecular mechanisms giving rise to nonhereditary PHPT.

Kasaian K, Wiseman SM, Thiessen N, et al.
Complete genomic landscape of a recurring sporadic parathyroid carcinoma.
J Pathol. 2013; 230(3):249-60 [PubMed] Related Publications
Parathyroid carcinoma is a rare endocrine malignancy with an estimated incidence of less than 1 per million population. Excessive secretion of parathyroid hormone, extremely high serum calcium level, and the deleterious effects of hypercalcaemia are the clinical manifestations of the disease. Up to 60% of patients develop multiple disease recurrences and although long-term survival is possible with palliative surgery, permanent remission is rarely achieved. Molecular drivers of sporadic parathyroid carcinoma have remained largely unknown. Previous studies, mostly based on familial cases of the disease, suggested potential roles for the tumour suppressor MEN1 and proto-oncogene RET in benign parathyroid tumourigenesis, while the tumour suppressor HRPT2 and proto-oncogene CCND1 may also act as drivers in parathyroid cancer. Here, we report the complete genomic analysis of a sporadic and recurring parathyroid carcinoma. Mutational landscapes of the primary and recurrent tumour specimens were analysed using high-throughput sequencing technologies. Such molecular profiling allowed for identification of somatic mutations never previously identified in this malignancy. These included single nucleotide point mutations in well-characterized cancer genes such as mTOR, MLL2, CDKN2C, and PIK3CA. Comparison of acquired mutations in patient-matched primary and recurrent tumours revealed loss of PIK3CA activating mutation during the evolution of the tumour from the primary to the recurrence. Structural variations leading to gene fusions and regions of copy loss and gain were identified at a single-base resolution. Loss of the short arm of chromosome 1, along with somatic missense and truncating mutations in CDKN2C and THRAP3, respectively, provides new evidence for the potential role of these genes as tumour suppressors in parathyroid cancer. The key somatic mutations identified in this study can serve as novel diagnostic markers as well as therapeutic targets.

de Mesquita Netto AC, Gomez RS, Diniz MG, et al.
Assessing the contribution of HRPT2 to the pathogenesis of jaw fibrous dysplasia, ossifying fibroma, and osteosarcoma.
Oral Surg Oral Med Oral Pathol Oral Radiol. 2013; 115(3):359-67 [PubMed] Related Publications
OBJECTIVE: To investigate HRPT2 in jaw ossifying fibroma (OF), fibrous dysplasia (FD), and osteosarcoma (OS).
STUDY DESIGN: We combined microsatellite loss of heterozygosity (LOH), HRPT2 sequence alterations at the mRNA level by reverse-transcription polymerase chain reaction (PCR), cDNA sequencing, and quantitative PCR (qPCR) and immunohistochemistry (IHC) in a total of 19 OF, 15 FD, and 9 OS. Because HRPT2 (parafibromin) interacts with cyclin D1, we investigated cyclin D1 expression with the use of qPCR and IHC.
RESULTS: LOH was detected in 3/5 FD, 6/9 OF, and 2/2 OS heterozygous samples. LOH was not associated with decreased mRNA levels or HRPT2 protein expression except for 1 OF which harbored an inactivating mutation. However, this tumor did not display altered transcription or protein levels of HRPT2 nor cyclin compared with the other OF.
CONCLUSIONS: The contribution of HRPT2 inactivation to the pathogenesis of OF, FD, and OS is marginal at best and may be limited to progression rather than tumor initiation.

Costa-Guda J, Imanishi Y, Palanisamy N, et al.
Allelic imbalance in sporadic parathyroid carcinoma and evidence for its de novo origins.
Endocrine. 2013; 44(2):489-95 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Parathyroid cancer is a rare, clinically aggressive cause of primary hyperparathyroidism, and whether these malignancies generally evolve from pre-existing benign adenomas or arise de novo is unclear. Furthermore, while inactivation of the CDC73 (HRPT2) tumor suppressor gene, encoding parafibromin, is a major contributor, other genes essential to parathyroid carcinogenesis remain unknown. We sought to identify genomic regions potentially harboring such oncogenes or tumor suppressor genes, and to gain insight into the origins and molecular relationship of malignant versus benign parathyroid tumors. We performed genome-wide copy-number and loss of heterozygosity analysis using Affymetrix 50K SNP mapping arrays and/or comparative genomic hybridization on 16 primary parathyroid carcinomas, local recurrences or distant metastases, and matched normal controls, from 10 individuals. Recurrent regions of allelic loss were observed on chromosomes 1p, 3, and 13q suggesting that key parathyroid tumor suppressor genes are located in these chromosomal locations. Recurrent allelic gains were seen on chromosomes 1q and 16, suggesting the presence of parathyroid oncogenes on these chromosomes. Importantly, the most common alteration in benign parathyroid adenomas, loss of 11q, was not found as a recurrent change in the malignant parathyroid tissues. Molecular allelotyping using highly polymorphic microsatellite markers provided further confirmation that the prevalence of 11q loss is markedly and significantly lower in carcinomas as compared with adenomas. Our observations provide molecular support for the concept that sporadic parathyroid cancer usually arises de novo, rather than evolving from a pre-existing typical benign adenoma. Furthermore, these results help direct future investigation to ultimately determine which of the candidate genes in these chromosomal locations make significant contributions to the molecular pathogenesis of parathyroid cancer.

Cui C, Lal P, Master S, et al.
Expression of parafibromin in major renal cell tumors.
Eur J Histochem. 2012; 56(4):e39 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Parafibromin, encoded by HRPT2 gene, is a recently identified tumor suppressor. Complete and partial loss of its expression have been observed in hyperparathyroidism-jaw tumor (HPT-JT), parathyroid carcinoma, breast carcinoma, lung carcinoma, gastric and colorectal carcinoma. However, little has been known about its expression in renal tumors. In order to study the expression of parafibromin in a series of the 4 major renal cell tumors - clear cell renal cell carcinoma (ccRCC), papillary renal cell carcinoma (pRCC), chromophobe renal cell carcinoma (chRCC) and oncocytoma. One hundred thirty nine renal tumors including 61 ccRCCs, 37 pRCCs, 22 chRCCs and 19 oncocytomas were retrieved and used for the construction of renal tissue microarrays (TMAs). The expression of parafibromin was detected by immunohistochemical method on the constructed TMAs. Positive parafibromin stains are seen in 4 out of 61 ccRCCs (7%), 7 out of 37 pRCCs (19%), 12 out of 23 chRCCs (52%) and all 19 oncocytomas (100%). Parafibromin expression varies significantly (P< 8.8 x10-16) among the four major renal cell tumors and were correlated closely with tumor types. No correlation of parafibromin expression with tumor staging in ccRCCs, pRCCs and chRCCs, and Fuhrman nuclear grading in ccRCCs and pRCCs. In summary, parafibromin expression was strongly correlated with tumor types, which may suggest that it plays a role in the tumorigenesis in renal cell tumors.

Bricaire L, Odou MF, Cardot-Bauters C, et al.
Frequent large germline HRPT2 deletions in a French National cohort of patients with primary hyperparathyroidism.
J Clin Endocrinol Metab. 2013; 98(2):E403-8 [PubMed] Related Publications
CONTEXT: Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is an autosomal dominant syndrome with incomplete penetrance that can associate in a single patient parathyroid adenoma or carcinoma, fibro-osseous jaw tumor, cystic kidney lesion, and uterine tumor. Germline mutations of the HRPT2 gene (CDC73) coding for parafibromin are identified in approximately 50%-75% of HPT-JT cases and in approximately 14% of familial isolated hyperparathyroidism. A whole deletion of this gene has recently been reported in 1 sporadic case and in a family presenting with HPT-JT.
OBJECTIVE: The objective of the study was to report molecular abnormalities of the HRPT2 gene in patients with primary hyperparathyroidism in a French National cohort from the Groupe d'Étude des Tumeurs Endocrines.
METHODS: Patients' genomic DNA was screened by PCR-based sequencing for point mutations affecting HRPT2 and real-time quantitative PCR analysis for gross deletions.
RESULTS: We report 20 index patients with a germinal HRPT2 abnormality. Median age at diagnosis of primary hyperparathyroidism was 23 years (range 14-65 years). Median serum total calcium level at diagnosis was 3.19 mmol/L (range 2.8-4.3 mmol/L). Thirteen different mutations were identified by routine sequencing, including 7 mutations never reported. Seven patients (35%) carried a gross deletion of this gene (3 complete and 4 partial deletions). No genotype-phenotype correlation could be identified. A gross deletion of the HRPT2 gene was identified in 7% of patients for whom a routine screening by direct sequencing came up as negative.
CONCLUSION: 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.

Bano G, Siedel V, Beharry N, et al.
A complex endocrine conundrum.
Fam Cancer. 2013; 12(3):577-80 [PubMed] Related Publications
We describe a case of recurrent primary hyperparathyroidism, manifested as 3 metachronous parathyroid adenomata, in a 50 year-old woman who also had Hashimoto hypothyroidism, gastric gastrointestinal stromal tumour (GIST), cysts in liver and kidneys, 5 intestinal polyps (one of these a villous adenoma), diverticulitis and telangiectasia of lips. She did not have medullary thyroid carcinoma (MTC). Genetic analysis of the CDC73 gene [for Hyperparathyroidism-jaw tumor (HPT-JT)], MEN1 for Multiple Endocrine Neoplasia Type1, CDKN1B for MEN4, SDHB and SDHD for Paraganglioma/Pheochromocytoma susceptibility, VHL for von Hippel-Lindau Syndrome, BMPR1A and SMAD4 for Juvenile Polyposis Syndrome (JPS) (sequencing and MLPA), karyotype and array CGH (44 K) were all normal. She was found to be homozygous for a synonomous germline variant in exon 14 (p. Ser836Ser) of the RET oncogene. This RET variant is of unclear clinical significance, and has been previously reported both in normal individuals and in individuals with MTC. It is unlikely that homozygosity for the RET variant has been casual in the multiple pathologies that our patient has developed.

Spinelli C, Liserre J, Pucci V, et al.
Primary hyperparathyroidism: fifth parathyroid intrathymic adenoma in a young patient.
J Pediatr Endocrinol Metab. 2012; 25(7-8):781-4 [PubMed] Related Publications
The clinical case described in this paper deals with a young female patient affected by primary hyperparathyroidism caused by an ectopic parathyroid adenoma of a supernumerary intrathymic parathyroid. The patient had hypercalcemia, in association with increased levels of parathormone, but was otherwise asymptomatic. Genetics tests for mutation of the MEN1, HRPT2, and CaSR genes were negative. She therefore underwent laboratory and instrumental tests but localization results in the neck were negative--only an intrathymic nodule was visualized. The complete surgical ablation of the thymus was conducted, which highlighted a nodule that, at histological examination, was shown to be an adenoma of a fifth parathyroid gland. The existence of a fifth, hyperfunctioning, intrathoracic parathyroid appears to be a rare cause of primary juvenile sporadic hyperparathyroidism. This peculiar clinical case could be of interest in similar cases evaluated by other surgeons.

Sulaiman L, Haglund F, Hashemi J, et al.
Genome-wide and locus specific alterations in CDC73/HRPT2-mutated parathyroid tumors.
PLoS One. 2012; 7(9):e46325 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
Mutations in the hyperparathyroidism type 2 (HRPT2/CDC73) gene and alterations in the parafibromin protein have been established in the majority of parathyroid carcinomas and in subsets of parathyroid adenomas. While it is known that CDC73-mutated parathyroid tumors display specific gene expression changes compared to CDC73 wild-type cases, the molecular cytogenetic profile in CDC73-mutated cases compared to unselected adenomas (with an expected very low frequency of CDC73 mutations) remains unknown. For this purpose, nine parathyroid tumors with established CDC73 gene inactivating mutations (three carcinomas, one atypical adenoma and five adenomas) were analyzed for copy number alterations and loss of heterozygosity using array-comparative genomic hybridization (a-CGH) and single nucleotide polymorphism (SNP) microarrays, respectively. Furthermore, CDC73 gene promoter methylation levels were assessed using bisulfite Pyrosequencing. The panel included seven tumors with single mutation and three with double mutations of the CDC73 gene. The carcinomas displayed copy number alterations in agreement with previous studies, whereas the CDC73-mutated adenomas did not display the same pattern of alterations at loci frequently deleted in unselected parathyroid tumors. Furthermore, gross losses of chromosomal material at 1p and 13 were significantly (p = 0.012) associated with parathyroid carcinomas as opposed to adenomas. Quantitative PCR-based copy number loss regarding CDC73 was observed in three adenomas, while all the carcinomas were diploid or showed copy number gain for CDC73 gene. Hypermethylation of the CDC73 gene promoter was not observed. Our data could suggest that CDC73-mutated parathyroid adenomas exhibit a partly unique cytogenetic profile in addition to that of carcinomas and unselected adenomas. Furthermore, CDC73-mutated carcinomas displayed losses at 1p and 13 which are not seen in CDC73-mutated adenomas, making these regions of interest for further studies regarding malignant properties in tumors from CDC73-mutated cases. However, due to the small sample size, validation of the results in a larger cohort is warranted.

Wang O, Wang C, Nie M, et al.
Novel HRPT2/CDC73 gene mutations and loss of expression of parafibromin in Chinese patients with clinically sporadic parathyroid carcinomas.
PLoS One. 2012; 7(9):e45567 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
OBJECTIVE: It is widely recognized that the diagnosis of parathyroid carcinoma (PC) is often difficult because of the overlap of characteristics between malignant and benign parathyroid tumors, especially at an early stage. Based on the identification of tumor suppressor gene HRPT2/CDC73 and its association with hereditary and sporadic PC, screening of gene mutations and detection of parafibromin immunoreactivity have been suggested as diagnostic instruments of PC in Whites. There is little information about HRPT2/CDC73 mutations and its corresponding protein expression in patients with sporadic PC in Chinese population, and the long-term follow-up data is scarce.
METHODS: Paraffin-embedded tissues were obtained from 13 patients with PC, 13 patients with parathyroid adenoma (PA) and 7 patients with parathyroid hyperplasia(PH), and 6 normal parathyroid (NP) tissues as controls. Peripheral blood from 11 patients with PC was collected. PCR products using Genomic DNA extracted from tumor tissues or blood as template was sequenced for HRPT2/CDC73 gene. Expression of parafibromin in tumor tissues was evaluated by immunohistochemical analysis.
RESULTS: Six mutations in 6 of 13 patients with PC were identified, with three being novel. Four of them were germ-line mutations. Patients with mutations were susceptible to recurrence of the PC. Complete (8/13, 61.5%) or partial (5/13, 38.5%) loss of parafibromin expression was observed in PC tissues. All of tissue samples from normal parathyroid or benign parathyroid tumors displayed positive immunostaining of parafibromin except one adenoma.
CONCLUSIONS: The present study supplies information on the mutations and protein expression of HRPT2/CDC73 gene and phenotypes of parathyroid carcinoma in Chinese population. And the expanded mutation database of this gene may benefit patients in the diagnosis and treatment of this disease.

Guarnieri V, Battista C, Muscarella LA, et al.
CDC73 mutations and parafibromin immunohistochemistry in parathyroid tumors: clinical correlations in a single-centre patient cohort.
Cell Oncol (Dordr). 2012; 35(6):411-22 [PubMed] Related Publications
OBJECTIVE: To determine if molecular and immunohistochemical (IHC) features of the HRPT2/CDC73 gene and its product, parafibromin, predict the natural history of parathyroid malignancy, particularly atypical adenoma, as seen in a single-centre patient cohort.
METHODS: Matched tumor and non-tumor tissues were obtained from 46 patients with parathyroid carcinoma (CA) (n = 15), atypical adenoma (AA) (n = 14) and typical adenoma (TA) (n = 17), as defined by standardized histopathological criteria. Exons and exon-intron boundaries of the CDC73 gene were sequenced to identify germline or somatic mutations. IHC staining for parafibromin was performed and scored as positive if nuclear staining was at least partially IHC-positive.
RESULTS: Mutations of CDC73 were observed in 9/15 (60 %) CA, 2/14 (14 %) AA, and 1/17 (6 %) TA tumors. A recurrent two basepair mutation in exon 7 -- c.679_680delAG -- accounted for half of all identified mutations. Absence of parafibromin nuclear staining was noted in 8/12 (67 %) CA, 2/13 (15 %) AA, and 3/17 (18 %) TA tumors. Median follow up times were 88 months for CA, 76 months for AA, and 104 months for TA patients. One patient, a member of a previously reported multiplex family with a germline CDC73 mutation was found to have a second adenoma after removal of an atypical adenoma.
CONCLUSIONS: Molecular screening and IHC are both useful tools in the differential diagnosis of parathyroid tumors, but both have limited sensitivity and specificity. CDC73 mutations and negative immunostaining were common in atypical adenomas, but no local recurrence was observed in any case with successful surgical removal after follow-up periods of 27 to 210 months.

Ghemigian A, Ghemigian M, Popescu I, et al.
Familial isolated primary hyperparathyroidism due to HRPT2 mutation.
Hormones (Athens). 2013 Jul-Sep; 12(3):454-60 [PubMed] Related Publications
Primary hyperparathyroidism is a common endocrine disorder that is mostly caused by solitary tumors within the parathyroid glands. Characterized by early debut and higher frequency of multiple parathyroid masses, familial forms of primary hyperparathyroidism are caused by the already known mutations of: menin (MEN1 syndrome), RET proto-oncogene (MEN2 syndrome), HRPT2-parafibromin (hyperparathyroidism-jaw tumor syndrome), calcium sensing receptor gene (familial hypocalciuric hypercalcemia). A specific mutation in FIHP has not been identified in the majority of affected families. Recent studies revealed menin, HRPT2 and calcium-sensing receptor mutations in patients with FIHP. Whether FIHP is a variant or an early stage of MEN1 syndrome or hyperparathyroidism-jaw tumor syndrome is yet to be established. We present three siblings with familial isolated hyperparathyroidism due to solitary parathyroid adenoma and favorable evolution post-parathyroidectomy. Genetic tests revealed HRPT2 mutation.

Sulaiman L, Nilsson IL, Juhlin CC, et al.
Genetic characterization of large parathyroid adenomas.
Endocr Relat Cancer. 2012; 19(3):389-407 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
In this study, we genetically characterized parathyroid adenomas with large glandular weights, for which independent observations suggest pronounced clinical manifestations. Large parathyroid adenomas (LPTAs) were defined as the 5% largest sporadic parathyroid adenomas identified among the 590 cases operated in our institution during 2005-2009. The LPTA group showed a higher relative number of male cases and significantly higher levels of total plasma and ionized serum calcium (P<0.001). Further analysis of 21 LPTAs revealed low MIB1 proliferation index (0.1-1.5%), MEN1 mutations in five cases, and one HRPT2 (CDC73) mutation. Total or partial loss of parafibromin expression was observed in ten tumors, two of which also showed loss of APC expression. Using array CGH, we demonstrated recurrent copy number alterations most frequently involving loss in 1p (29%), gain in 5 (38%), and loss in 11q (33%). Totally, 21 minimal overlapping regions were defined for losses in 1p, 7q, 9p, 11, and 15q and gains in 3q, 5, 7p, 8p, 16q, 17p, and 19q. In addition, 12 tumors showed gross alterations of entire or almost entire chromosomes most frequently gain of 5 and loss of chromosome 11. While gain of 5 was the most frequent alteration observed in LPTAs, it was only detected in a small proportion (4/58 cases, 7%) of parathyroid adenomas. A significant positive correlation was observed between parathyroid hormone level and total copy number gain (r=0.48, P=0.031). These results support that LPTAs represent a group of patients with pronounced parathyroid hyperfunction and associated with specific genomic features.

Cetani F, Pardi E, Borsari S, Marcocci C
Molecular pathogenesis of primary hyperparathyroidism.
J Endocrinol Invest. 2011; 34(7 Suppl):35-9 [PubMed] Related Publications
Primary hyperparathyroidism (PHPT) is a common endocrinopathy, mostly caused by a monoclonal parathyroid adenoma. The hereditary syndromes include multiple endocrine neoplasia types 1 (MEN 1) and 2A (MEN 2A), hereditary hyperparathyroidism-jaw tumor (HPTJT), familial isolated hyperparathyroidism (FIHP), familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NSHPT). Mutations of MEN1 and CDKN1B genes are responsible for MEN 1 in 70-80% and about 2% of cases, respectively. MEN1 and CDKN1B genes have also a role in the pathogenesis of sporadic parathyroid adenomas. HRPT2/CDC73 gene mutations are responsible for HPT-JT and sporadic parathyroid carcinoma. MEN1 and HRPT2/CDC73 genes mutations have also been found in a subset of FIHP families. FHH and NSHPT represent the mildest and severest variants of PHPT, caused by heterozygous and homozygous mutations in the calcium sensing receptor (CASR) gene, respectively.

Cascón A, Huarte-Mendicoa CV, Javier Leandro-García L, et al.
Detection of the first gross CDC73 germline deletion in an HPT-JT syndrome family.
Genes Chromosomes Cancer. 2011; 50(11):922-9 [PubMed] Related Publications
Hereditary primary hyperparathyroidism (HPT) may develop as a solitary endocrinopathy (FIHP) or as part of multiple endocrine neoplasia Type 1, multiple endocrine neoplasia Type 2A, or hereditary HPT-jaw tumor syndrome. Inactivating germline mutations of the tumor suppressor gene CDC73 account for 14 and 50% of all FIHP and HPT-JT patients, respectively, and have also been found in almost 20% of apparently sporadic parathyroid carcinoma patients. Although more than 60 independent germline mutations have been described, to date no rearrangement affecting the CDC73 locus has been identified. By means of multiplex-PCR we found a large germline deletion affecting the whole gene in a two-generation HPT-JT family. Subsequently array-CGH and specific PCR analysis determined that the mutation spanned ∼ 547 kb, and included four additional genes: TROVE2, GLRX2, B3GALT2, and UCHL5. Although no clear mutation-specific phenotype was found associated to the presence of the mutation, further studies are needed to assess whether the loss of the neighboring genes could modify the phenotype of carriers. There was complete absence of nuclear staining in the two HPT-JT-related tumors available. The finding of the first rearrangement affecting the CDC73 gene warrants screening for this tumor suppressor gene inactivation mechanism not only in high-risk CDC73 point mutation-negative HPT-JT families, but also in FIHP patients.

Siu WK, Law CY, Lam CW, et al.
Novel nonsense CDC73 mutations in Chinese patients with parathyroid tumors.
Fam Cancer. 2011; 10(4):695-9 [PubMed] Related Publications
Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is an autosomal dominant disease characterized by the occurrences of parathyroid tumors and ossifying fibroma of maxilla/mandible. It is caused by mutations in CDC73 gene and mutation carriers are at increased risk of parathyroid carcinoma. Hyperparathyroidism could be the sole manifestation. We reported two Chinese patients having parathyroid neoplasm with equivocal malignant potential and parathyroid carcinoma respectively with both germline and somatic CDC73 mutations detected. Both of them presented with severe hypercalcemia and primary hyperparathyroidism with no other HPT-JT associated tumors and negative family history. We identified one novel germline mutation CDC73 NM_024529.4: c.1475G > A; NP_078805.3: p.Trp492X and one novel somatic mutation CDC73 NM_024529.4: c.142G > T; NP_078805.3: p.Glu48X. The other germline mutation CDC73 NM_024529.4: c.226C > T; NP_078805.3: p.Arg76X and somatic mutation CDC73 NM_024529.4: c.85delG; NP_078805.3: p.Glu29SerfsX8 were previously reported. This is the first report of CDC73 mutations in the Chinese population. Genetic analysis is reliable to confirm the underlying hereditary basis of hyperparathyroidism. By identification of mutations, the patient and the family members could benefit from regular surveillance for early detection of tumors.

Niramitmahapanya S, Sunthornthepvarakul T, Deerochanawong C, et al.
Sensitivity of HRPT2 mutation screening to detect parathyroid carcinoma and atypical parathyroid adenoma of Thai patients.
J Med Assoc Thai. 2011; 94 Suppl 2:S17-22 [PubMed] Related Publications
OBJECTIVE: Detected HRPT2 mutation in parathyroid carcinoma or atypical parathyroid adenoma in sporadic hyperparathyroidism in Thai patients.
MATERIAL AND METHOD: Samples of parathyroid carcinoma, typical (atypical) adenoma or hyperplasia were obtained for HRPT2 gene (17 exons) study since September 2001 to August 2010 both somatic and germline by SyBr Green PCR method.
RESULTS: Parathyroid carcinomas and atypical parathyroid adenoma from 5 of 26 patients (10 of 32 samples) were tested for HRPT2 mutations. Only somatic HRPT2 mutations were found in tumor from 2 patients but three patients found both somatic and germline HRPT2 mutations. Exon 15 of HRPT2 gene was the best sensitivity (sensitivity 80.0%; p < 0.001, 95% CI 0.75-1.05) followed by exon 2 and exon 11 (sensitivity 60.0%; p = 0.007, 95% CI 0.60-0.99) to detected parathyroid carcinoma or atypical parathyroid adenoma.
CONCLUSION: HRPT2 mutations by SyBr Green PCR sensitive method to detected parathyroid carcinoma or atypical adenoma from benign parathyroid tissues. Exon 15 was the best sensitive to detected parathyroid carcinoma or atypical adenoma. Genotyping of such family members for germline mutation would focus implementation of clinical and biochemical monitoring of carriers of these mutations.

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