Sporadic Parathyroid Carcinoma Research Articles

7508 Primary Hyperparathyroidism Caused By A CDC73-related Atypical Parathyroid Tumor

Abstract Disclosure: R. Cardenas: None. S. Tariq: None. R. Habibi: None. N. Ebrahimi: None. E. Astiazaran-Symonds: None. Background: Primary hyperparathyroidism (PHPT) is a common endocrine disease, causes include: parathyroid adenomas (80-85%), parathyroid hyperplasia (10-15%), atypical parathyroid adenomas (APA) (1.2 %) and parathyroid carcinomas (PC) (1%). APA share many anatomic and histopathologic features with PC making the distinction between the two challenging. Although most are sporadic, some APA are caused by germline mutations in the CDC73 gene, which is associated with hyperparathyroidism-jaw tumor (HPT-JT) syndrome PC and familial isolated PHPT with APA. Clinical Case: A 42-year-old female presented to the clinic for evaluation of recurrent PHPT. She was diagnosed at age 22 when she experienced fatigue, polydipsia with hypercalcemia (12.9mg/dl). She underwent superior bilateral parathyroidectomy with pathology consistent with parathyroid adenoma. Twenty years later, symptoms recurred and tests showed hypercalcemia (13.0 mg/dl), elevated PTH (252 pg/dl), kidney function preserved (GFR: 82.5 ml/min), normal vitamin D 25 OH (31 ng/dl). Patient denied history of nephrolithiasis or fractures. Family history was positive for kidney stones in father and siblings, also history of a jaw tumor in niece. Sestamibi scan showed a left inferior parathyroid adenoma. Patient underwent resection of the adenoma; pathology revealed a left parathyroid adenoma with atypical parathyroid tumor, >95% cellularity with cytologic features concerning for malignancy, prominent macronucleoli, necrosis, elevated mitotic activity and Ki67 with 15% tumor cells without vascular invasion. Post-op Calcium and PTH normalized (9.6 mg/dl and 10.8 pg/ml, respectively). Genetic testing via multi-gene panel identified a whole gene deletion of CDC73, consistent with hyperparathyroidism-jaw tumor syndrome. Panoramic jaw x-rays did not show jaw tumors. Genetic testing for family members is underway. Conclusion: Although somatic mutations in CDC73 are frequently found in sporadic APA and PC, germline mutations are a rare cause of PHPT associated with these tumors. Histopathological examination is necessary to confirm the diagnosis of APA and to differentiate it from PC, which has a recurrence rate >50%. APA should be treated as a “tumor of uncertain malignant potential” and needs to be carefully and periodically followed up with measurement of Ca, PTH and vitamin D. Confirmation of a CDC73 mutation by genetic testing helped identify the increased risk for other associated tumors in jaw, kidneys and uterus prompting initiation of surveillance with panoramic jaw x-rays with neck shielding, renal US and pelvis US. Genetic testing of family members will allow timely detection and treatment of individuals at risk. Presentation: 6/3/2024

Phenotype of Parathyroid-targeted Cdc73 Deletion in Mice Is Strain-dependent.

Hyperparathyroidism jaw-tumor syndrome is an autosomal dominant disorder caused by mutations in the CDC73/HRPT2 tumor suppressor gene, encoding parafibromin, and manifesting benign or malignant parathyroid tumors, ossifying jaw fibromas, uterine tumors, and kidney lesions. Sporadic parathyroid carcinomas also frequently exhibit inactivating CDC73 mutations and loss of parafibromin. To study the role of CDC73 in parathyroid cell proliferation in vivo, we generated mice with a parathyroid-specific deletion of Cdc73. Homozygous knockout mice on a mixed B6/129/CD1 background had decreased serum calcium and PTH and smaller parathyroid glands compared with heterozygous or wild-type littermates, whereas homozygous Cdc73-null mice on other backgrounds exhibited no abnormalities in parathyroid gland function or development. No hypercalcemia or parathyroid hypercellularity was observed in mice of any background examined at any age. Thus, although postnatally acquired complete loss of CDC73 causes parathyroid cell proliferation and hyperparathyroidism, such as seen in human hyperparathyroidism jaw-tumor syndrome, our results suggest that earlier, developmentally imposed complete loss of Cdc73 can cause a primary defect in parathyroid gland structure/function in a strain-dependent manner. This striking disparity in parathyroid phenotype related to genetic background offers a unique opportunity in an in vivo model system to precisely dissect and identify the responsible molecular mechanisms.

FRI686 Phenotypic Profiling And Molecular Mechanisms In Hyperparathyroidism-jaw Tumor Syndrome

Abstract Disclosure: R. Tora: None. J. Welch: None. J. Sun: None. S.K. Agarwal: None. D.A. Bell: None. M. Merino: None. L.S. Weinstein: None. W.F. Simonds: None. S. Jha: None. Background: Hyperparathyroidism-Jaw Tumor (HPT-JT) syndrome is a heritable form of primary hyperparathyroidism (PHPT) that is associated with tumors in the parathyroid, jaw, kidney, and uterus. We previously presented on the clinical characteristics of primary hyperparathyroidism in our cohort. Methods: We now expand on the report through review of uterine tumors, immunohistochemical staining for parafibromin, sequencing of parathyroid and kidney tumor tissue, and RNA-seq of parathyroid tumors. Results: We identified 68 patients (36 males, 32 females) from 29 kindreds with HPT-JT with median age at last follow-up of 39 [29-53] years. Of these, 7 patients were unaffected (2 males, 5 females). Among females, 12/32 (38%) developed uterine tumors with multiple adenomyomatous polyps, an unusual form of endometrial polyps seen in 10/24 tumors (42%). Given that these types of lesions are very rare in the general population, it is likely that such epithelial-mesenchymal uterine proliferations are a characteristic feature of HPT-JT syndrome.Solid kidney tumors were seen in 4/61 patients (7%). Three had surgery for the tumors - 2/3 were female and had mixed epithelial stromal tumor, while the third patient, a 6-year old male, had metastatic Wilm’s tumor as his initial disease-related manifestation. Among these, two had a germline CDC73 variant at the p.M1 residue while the third patient had the germline variant p.L95P; however, sequencing of his tumor tissue showed a “second hit” at the p.M1 residue resulting in loss of heterozygosity in the tumor. The fourth patient, a female with p.Y55S variant, is being conservatively managed with no kidney surgery yet. All three women with kidney tumors also had a history of uterine tumors. Parafibromin staining of 19 available CDC73 related parathyroid tumors (13 adenomas and 6 carcinoma) did not correlate with histology or genotype. Pathway analysis of 21 parathyroid tumors (8 HPT-JT-related adenomas, 6 HPT-JT-related carcinomas and 7 sporadic parathyroid carcinoma with wild-type CDC73) showed a significant association of HPT-JT-related parathyroid carcinoma with growth, transmembrane receptor protein tyrosine kinase signaling and mesodermal commitment pathways. Conclusion: Multiple, recurrent atypical adenomyomatous uterine polyps appear to be characteristic of HPT-JT syndrome. Our findings support germline testing at a young age in first-degree relatives of patients with HPT-JT given onset of manifestations as early as 6 years. Variants at M1 residue appear to predispose to genitourinary tumors. At present, there are no therapeutic approaches to compensate for CDC73 inactivation. Future research to identify standards of care and therapeutics targets are warranted for this rare disease. Presentation: Friday, June 16, 2023

FRI692 Severe Hyperparathyroidism And Nephrolithiasis In An Adolescent Male Due To CDC73 Positive Parathyroid Carcinoma

Abstract Disclosure: J.T. Nguyen: None. D.H. Geller: None. A. Ryabets-Lienhard: None. Introduction: Parathyroid carcinoma is a rare cause of primary hyperparathyroidism in the pediatric population, with only 20 previously reported cases. Variations in the CDC73 gene have been associated with sporadic parathyroid carcinoma, autosomal dominant hyperparathyroidism-jaw tumor syndrome (HPT-JT), and familial isolated hyperparathyroidism (FIHP). To our knowledge, only 3 cases of pediatric parathyroid carcinoma with confirmed variants of CDC73 have been reported. We present a case of severe hyperparathyroidism and nephrolithiasis due to parathyroid carcinoma caused by a pathogenic variant in CDC73 in a pediatric patient, highlighting the importance of early recognition and management. Clinical Case: An otherwise asymptomatic 14-year-old male presented with one year of recurrent nephrolithiasis. Initial tests demonstrated hypercalcemia (13.8 mg/dL, 8.4-10.2 mg/dL), normal phosphorous, elevated PTH (1,379 pg/mL, 7.5-53.5 pg/mL), and elevated alkaline phosphatase (514 U/L, 30-250 U/L). The hypercalcemia was treated with hyperhydration, furosemide, and pamidronate. Sestamibi scan revealed a focus of abnormal uptake suggestive of a left parathyroid mass, with ultrasonographic demonstration of a predominantly solid, hypoechoic, and vascular mass centered posterior to the inferior left thyroid lobe. Skeletal survey was notable for trabecular abnormalities and osteopenia. He underwent a left parathyroid mass excision. Final pathology confirmed the parathyroid carcinoma, with multiple foci of vascular invasion without evidence of capsular involvement. Immunohistochemistry demonstrated diffuse positivity for PTH and loss of parafibromin expression by the tumor cells. Genetic testing revealed a pathogenic germline heterozygous nonsense variant in CDC73 (c.376C>T(p.Arg126Ter)) resulting in protein truncation. Post-operative PTH was undetectable with normal calcium and phosphorous. Calcitriol, cholecalciferol, and calcium carbonate supplementation were implemented to prevent further hypocalcemia due to transient hypoparathyroidism and hungry bone syndrome. Calcium supplementation was discontinued within one year of his surgery. Serial thyroid ultrasounds and CT scans have been negative for recurrent or residual disease without evidence of metastasis. Mandibular x-ray showed no evidence of tumors or lesions involving the jaw. He has been noted to have small right renal cysts without other kidney abnormalities. Conclusion: Severe hyperparathyroidism due to parathyroid carcinoma can present as recurrent nephrolithiasis in an otherwise asymptomatic individual. Pediatric patients with a longstanding history of kidney stones should undergo screening for hypercalcemia and hyperparathyroidism even in the absence of other signs and symptoms of elevated calcium to ensure timely diagnosis and appropriate management. Presentation: Friday, June 16, 2023

PSUN363 GCM2 variants in Parathyroid Carcinoma

Abstract Germline, in vitro activating GCM2 variants are notably overrepresented in patients with primary hyperparathyroidism (PHPT), in both the familial and sporadic settings. While increased compared with the general population, most individuals with such variants in the population have a very low risk of developing PHPT. However, for those individuals who do develop PHPT, the degree to which harboring such a variant might impact the disease severity remains unclear. An increased likelihood of multigland involvement and a lower rate of biochemical cure has been reported in GCM2variant-positive patients as compared with variant-negative patients. In the context of familial isolated primary hyperparathyroidism, one individual with a GCM2 Y394S variant was reported to have developed parathyroid carcinoma (Guan, 2016) and another developed parathyromatosis (Koh, 2021). In another family, carrying I383M, parathyroid carcinoma was seen in one individual and atypical adenoma in another (Canaff, 2022). No GCM2 variants were noted in two other kindreds which included at least one individual with parathyroid carcinoma, for which other known causes of FIHP had already been ruled out (Cetani, 2019). Rare GCM2 variants were reported in three patients with sporadic parathyroid carcinoma: two with K388E (Song, 2020) and one with V382M (Canaff, 2022). V382M was also observed in a patient with atypical adenoma (Song, 2020). No GCM2 variants have been reported in whole exome sequencing (WES) studies of parathyroid carcinoma. However, in 45% of reported cases subjected to WES, germline variants were specifically filtered out during data analysis. In the remaining reported cases for which germline DNA was unavailable, filtering would have excluded common variants, such as Y282D, but rare GCM2 variants may have been detectable. We sought to determine the frequency of GCM2 germline variants of interest in a series of 15 sporadic parathyroid carcinomas by direct DNA sequencing. No sequence variants were identified within the C-terminal conserved inhibitory domain (CCID) of GCM2, nor was the PHPT-associated Y282D variant found in any of our samples. Across all studies to date, GCM2 CCID variants have been detected in 3 of 48 (6.25%) sporadic parathyroid carcinomas and Y282D in 4 of 56 (7.14%) of cases. Our results demonstrating a dearth of GCM2 variants in individuals with parathyroid carcinoma, combined with the absence of malignancy in the overwhelming majority of patients harboring PHPT-associated GCM2 variants, suggest individuals in the general population with such variants are at exceedingly low risk of developing parathyroid carcinoma. However, some very rare variants, such as I383M, might be show higher penetrance. Given the potential implications for surveillance/monitoring approaches and/or surgical decision making, the hypothesis that in certain genetic and/or environmental contexts GCM2 variants may be associated with more severe clinical phenotypes merits further investigation. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Genetics and Epigenetics of Parathyroid Carcinoma.

Parathyroid carcinoma (PC) is an extremely rare malignancy, accounting less than 1% of all parathyroid neoplasms, and an uncommon cause of primary hyperparathyroidism (PHPT), characterized by an excessive secretion of parathyroid hormone (PTH) and severe hypercalcemia. As opposed to parathyroid hyperplasia and adenomas, PC is associated with a poor prognosis, due to a commonly unmanageable hypercalcemia, which accounts for death in the majority of cases, and an overall survival rate of 78-85% and 49-70% at 5 and 10 years after diagnosis, respectively. No definitively effective therapies for PC are currently available. The mainly employed treatment for PC is the surgical removal of tumoral gland(s). Post-surgical persistent or recurrent disease manifest in about 50% of patients. The comprehension of genetic and epigenetic bases and molecular pathways that characterize parathyroid carcinogenesis is important to distinguish malignant PCs from benign adenomas, and to identify specific targets for novel therapies. Germline heterozygote inactivating mutations of the CDC73 tumor suppressor gene, with somatic loss of heterozygosity at 1q31.2 locus, account for about 50-75% of familial cases; over 75% of sporadic PCs harbor biallelic somatic inactivation/loss of CDC73. Recurrent mutations of the PRUNE2 gene, a recurrent mutation in the ADCK1 gene, genetic amplification of the CCND1 gene, alterations of the PI3K/AKT/mTOR signaling pathway, and modifications of microRNA expression profile and gene promoter methylation pattern have all been detected in PC. Here, we review the current knowledge on gene mutations and epigenetic changes that have been associated with the development of PC, in both familial and sporadic forms of this malignancy.

Novel Glial Cells Missing-2 (GCM2) variants in parathyroid disorders.

ObjectiveThe aim of this study was to analyze variants of the gene glial cells missing-2 (GCM2), encoding a parathyroid cell-specific transcription factor, in familial hypoparathyroidism and in familial isolated hyperparathyroidism (FIHP) without and with parathyroid carcinoma.DesignWe characterized 2 families with hypoparathyroidism and 19 with FIHP in which we examined the mechanism of action of GCM2 variants.MethodsLeukocyte DNA of hypoparathyroid individuals was Sanger sequenced for CASR, PTH, GNA11 and GCM2 mutations. DNA of hyperparathyroid individuals underwent MEN1, CDKN1B, CDC73, CASR, RET and GCM2 sequencing. The actions of identified GCM2 variants were evaluated by in vitro functional analyses.ResultsA novel homozygous p.R67C GCM2 mutation which failed to stimulate transcriptional activity in a luciferase assay was identified in affected members of two hypoparathyroid families. Oligonucleotide pull-down assay and in silico structural modeling indicated that this mutant had lost the ability to bind the consensus GCM recognition sequence of DNA. Two novel (p.I383M and p.T386S) and one previously reported (p.Y394S) heterozygous GCM2 variants that lie within a C-terminal conserved inhibitory domain were identified in three affected individuals of the hyperparathyroid families. One family member, heterozygous for p.I138M, had parathyroid carcinoma (PC), and a heterozygous p.V382M variant was found in another patient affected by sporadic PC. These variants exerted significantly enhanced in vitrotranscriptional activity, including increased stimulation of the PTH promoter.ConclusionsWe provide evidence that two novel GCM2 R67C inactivating mutations with an inability to bind DNA are causative of hypoparathyroidism. Additionally, we provide evidence that two novel GCM2 variants increased transactivation of the PTH promoter in vitro and are associated with FIHP. Furthermore, our studies suggest that activating GCM2 variants may contribute to facilitating more aggressive parathyroid disease.

A case report of a patient with parathyroid carcinoma and a CDC73 germline mutation

Background: Parathyroid carcinoma (PC) is an uncommon cause of primary hyperparathyroidism (pHPT). Mutations of the cell division cycle protein 73 homolog (CDC73) gene are associated with both sporadic and familial pHPT and PC, including hyperparathyroidism-jaw tumor (HPT-JT) syndrome. Case Presentation: A 38-year-old man presented with severe hypercalcemia and acute renal injury due to pHPT. He had a palpable left cervical mass of 50 mm, characterized by both ultrasound and 99mTc-sestamibi scintigraphy as an enlarged hyperfunctioning parathyroid gland. Histological diagnosis after parathyroidectomy was of PC. During follow-up, patient developed metastasis of the skin, mediastinal lymph-nodes, and lungs. Even after surgical excision of all detectable metastasis parathyroid hormone (PTH) remained elevated. Genetic analysis found a germline mutation (c.766_767delGT) of the CDC73 gene, which was not previously reported in PC. Conclusion: Germline CDC73 analysis may be considered in HPT-JT syndrome, familial isolated pHPT, PC, and young individuals with pHPT.

SAT-334 A Genetic Cause of Primary Hyperparathyroidism

Background: Primary hyperparathyroidism is a relatively common endocrine condition, affecting up to 7 out of every 1000 adults. Median age of onset is during the sixth decade of life. When present in younger patients primary hyperparathyroidism may indicate an underlying genetic cause. Case: A 23-year-old woman is referred for evaluation of hypercalcemia that was found on labs drawn after surgery for bilateral ovarian cyst removal. At the time of presentation she felt well and was without complaint. Her medical history is otherwise unremarkable. Her family history includes multiple family members with nephrolithiasis. Physical exam revealed a well appearing Caucasian woman without a palpable neck mass. Laboratory results showed: serum calcium 11.7 mg/dL (ref 8.4–10.2), ionized calcium 1.44 mmol/L (ref 1.12–1.32) and serum PTH 192 pg/mL (ref 11–65). Technetium-99 sestamibi scan revealed a low attenuating mass with focal and persistent uptake just inferior to the left thyroid lobe. She subsequently underwent left inferior parathyroidectomy, which confirmed parathyroid adenoma, with resultant normalization of serum calcium and PTH. Due to her young age of diagnosis genetic testing was performed which revealed a mutation if CDC 73. Discussion: CDC 73 mutation is known cause of inheritable neoplasia’s with a high prevalence of parathyroid dysfunction. Although penetrance and expression is variable, the mutation is associated primarily with Hyperparathyroidism Jaw Tumor Syndrome (HPT-JT), Familial Isolated Hyperparathyroidism and sporadic parathyroid carcinoma. Our patient had an allele mutation associated with HPT-JT. This syndrome classically presents with parathyroid adenoma, ossifying tumors of the mandible and renal or uterine neoplasms. The mutation is inherited in an autosomal dominant pattern and family history plays a key role in diagnosis of this rare condition. This patient had an early age of onset for hyperparathyroidism and a family history suggestive of an inherited calcium metabolism disorder. A single parathyroid adenoma is the most common presentation and surgical resection is often curative of hyperparathyroidism. In Hyperparathyroidism Jaw Tumor Syndrome patients classically develop ossifying tumors of the mandible and renal or uterine neoplasms in addition to parathyroid lesions. Rarely patients with CDC 73 mutation can develop parathyroid carcinoma. For this reason it is recommended that all first degree relatives undergo testing for CDC 73 mutation. This patient currently has no evidence of jaw, uterine or renal tumors on screening imaging. Ovarian tumors have been described separately to be associated with CDC 73 mutation, this patient may actually have an unrecognized phenotype of CDC 73 mutation. Given the potential impact of inheritable neoplasia, all young patients with unexplained hyperparathyroidism should be considered for genetic screening.

MON-LB060 Atypical Presentation of Parathyroid Carcinoma: Case Report

Background: Parathyroid carcinoma is a rare cause of primary hyperparathyroidism (0.74%), with an incidence of 0.36 (2000-2012), age presentation between 44-54 y/o, and symptoms associated with neck mass, bone and renal disease, as a consequence of marked hypercalcemia and elevated Parathyroid Hormone (PTH)1. Clinical Case: 85 y/o male, with 12-month history of weight loss (20Kg) along with unstable gait, laboratory with incidental findings of hypercalcemia (serum Calcium: 15.5mg/dL) and elevated PTH (PTH: 1141pg/mL). SESTAMIBI SPECT showed increased uptake in the inferior left thyroid lobe. Patient is admitted for elective parathyroidectomy with diagnosis of parathyroid adenoma. Patient had well-controlled hypertension and denied bone fractures, kidney stones, neck nodules or tumors. On physical exam, no visible or palpable neck mass was evident. Repeat admission lab results confirm malignant hypercalcemia: calcium: 14.14mg/dL, PTH: 1262pg/mL, creatinine: 2.34mg/dL. Surgery Findings: calcified enlarged left thyroid mass with no clear parathyroid definition. Mass is removed along with lymph nodes. Hypercalcemia and elevated PTH persists postoperatively (Serum calcium: 15.2mg/dL, PTH: 1552pg/mL) and patient is started on zoledronic acid with good response. Final pathology report: neoplastic ovoid and round cells, fibrous bands circumscribing lobes, acinar and trabecular structures with plexiform vasculature, areas of necrosis and calcifications with venous angioinvasion: parathyroid carcinoma. Oncology discharges patient with palliative care upon family request. Being a sporadic parathyroid carcinoma, genetic testing for germline HRPT2 (CDC73) mutations is requested. No mutations were detected. Conclusion: Parathyroid carcinoma is a rare endocrine tumor, with a 5-year survival rate of 64,8% upon complete tumor resection. Our patient represents one of the few case reports on silent parathyroid carcinoma in an elderly patient with residual disease currently on pharmacological management for persistent hypercalcemia, and negative genetic testing. Key words: parathyroid carcinoma, hyperparathyroidism, hypercalcemia, HRPT2 (CDC73) gen

Molecular genetic insights into sporadic primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a common endocrine disorder characterized by dysregulation of parathyroid hormone release. The large majority of PHPT cases are attributable to sporadic, single-gland parathyroid adenoma, in which MEN1 and CCND1/cyclin D1 are the most well-established drivers of tumorigenesis. Sporadic parathyroid carcinoma, which appears to mostly arise through molecular pathways distinct from those causing benign parathyroid tumors, is rare and is most frequently driven by mutational inactivation of the CDC73 (HRPT2) tumor suppressor gene. Targeted investigation of suspected tumor driver genes, as well as unbiased whole-genome or exome sequencing of small cohorts, have revealed additional novel candidate tumor genes in sporadic parathyroid neoplasia, generally at modest or low mutational frequencies consistent with marked molecular genetic heterogeneity from tumor to tumor. The ability of these additional candidates to participate in the pathogenic process of driving parathyroid tumorigenesis in vivo largely remains to be demonstrated experimentally. This review will summarize the molecular genetic abnormalities identified to date in sporadic PHPT and discuss the strength of evidence for their proposed roles in parathyroid tumor formation.

Comprehensive Genomic Characterization of Parathyroid Cancer Identifies Novel Candidate Driver Mutations and Core Pathways.

ContextElucidating the genomic landscape of sporadic parathyroid carcinoma (PC) has been limited by low tumor incidence.ObjectiveIdentify driver mutations of sporadic PC and potential actionable pathways.MethodsPatients undergoing surgical resection for sporadic PC between 1980 and 2016 at MD Anderson Cancer Center were identified. Patients with sporadic PC according to World Health Organization diagnostic criteria and with available formalin-fixed, paraffin-embedded (FFPE) PC tumor tissue were included and their clinical data analyzed to assess extent of disease. Patients with parathyroid tumors of uncertain malignancy or atypical parathyroid neoplasms were excluded. Thirty-one patients meeting diagnostic criteria had available tissue for analysis. FFPE PC tumors were subjected to DNA extraction and next-generation whole-exome sequencing. All variant calls are single-algorithm only. Twenty-nine samples passed quality assurance after DNA extraction.Main Outcome MeasuresSomatic or private germline mutations present in sporadic PC and identification of pathways involved in tumorigenesis.ResultsWe identified 35 genes with considerable mutational load; only eight genes were previously identified in other PC cohorts. These genes mediate critical processes, including chromosome organization, DNA repair, and cell cycle regulations. Gene mutations involved in MAPK signaling and immune response are also heavily implicated. These findings are limited by inherent molecular artifacts in FFPE tissue analysis and the absence of matched germline DNA. Additionally, variant calls are only single algorithm and may include false-positive/negative calls.ConclusionWe identified 33 candidate driver genes of sporadic PC, in addition to previously known driver genes CDC73 and MEN1.

Parathyroid carcinoma

Parathyroid carcinoma is a rare but clinically-aggressive tumor. While most cases are sporadic, parathyroid cancer is overrepresented in hyperparathyroidism-jaw tumor syndrome, or rarely other heritable syndromes. Evidence suggests that sporadic parathyroid carcinomas rarely, if ever, evolve through an identifiable benign tumor intermediate. A few genes have been directly implicated in the pathogenesis of sporadic parathyroid cancer; somatic (and less common germline) mutations in the CDC73 tumor suppressor gene are the most frequent finding and the only firmly established molecular drivers of parathyroid cancer. Alterations in other important human cancer genes, including CCND1/cyclin D1, PIK3CA, MTOR and PRUNE2 have also been described in parathyroid cancer, however their abilities to drive malignant parathyroid tumorigenesis remains to be demonstrated experimentally.

Large deletion at the CDC73 gene locus and search for predictive markers of the presence of a CDC73 genetic lesion.

The Hyperparathyroidism with Jaw-Tumours syndrome is caused by mutations of the CDC73 gene: it has been suggested that early onset of the disease and high Ca2+ levels may predict the presence of a CDC73 mutation. We searched for large deletions at the CDC73 locus in patients with: HPT-JT (nr 2), atypical adenoma (nr 7) or sporadic parathyroid carcinoma (nr 11) with a specific MLPA and qRT-PCR assays applied on DNA extracted from whole blood. A Medline search in database for all the papers reporting a CDC73 gene mutation, clinical/histological diagnosis, age at onset, Ca2+, PTH levels for familial/sporadic cases was conducted with the aim to possibly identify biochemical/clinical markers predictive, in first diagnosis, of the presence of a CDC73 gene mutation. A novel genomic deletion of the first 10 exons of the CDC73 gene was found in a 3-generation HPT-JT family, confirmed by SNP array analysis. A classification tree built on the published data, showed the highest probability of having a CDC73 mutation in subjects with age at the onset < 41.5 years (44/47 subjects, 93.6%, had the mutation). Whereas the lowest probability was found in subjects with age at the onset ≥ 41.5 years and Ca2+ levels <13.96 mg/dL (7/20 subjects, 35.0%, had the mutation, odds ratio = 27.1, p < 0.001). We report a novel large genomic CDC73 gene deletion identified in an Italian HPT-JT family. Age at onset < 41.5 ys and Ca2+ > 13.96 mg/dL are predictive for the presence of a CDC73 genetic lesion.

CDC73-Related Disorders: Clinical Manifestations and Case Detection in Primary Hyperparathyroidism.

Heterozygous pathogenic germline variants in CDC73 predispose to the development of primary hyperparathyroidism (pHPT) and, less frequently, ossifying fibroma of the jaw and renal and uterine tumors. Clinical information on CDC73-related disorders has so far been limited to small case series. To assess the clinical manifestations and penetrance in CDC73-related disorders and to improve case detection in pHPT. Nationwide retrospective Dutch cohort study. Tertiary referral center. We studied 89 patients with pHPT referred for germline CDC73 analysis and 43 subsequently tested relatives who proved to be mutation carriers. Germline CDC73 mutation analysis. CDC73 mutation detection yield, referral rate, and CDC73-related disease penetrance. Pathogenic germline CDC73 variants were identified in 11 of the 89 referred pHPT patients (12.4%), with (suspected) hyperparathyroidism-jaw tumor (HPT-JT) syndrome (n = 3), familial isolated pHPT (n = 5), apparently sporadic parathyroid carcinoma (n = 2), and apparently sporadic parathyroid adenoma (n = 1). The estimated penetrance of CDC73-related disorders was 65% at age 50 years (95% confidence interval, 48% to 82%) in 43 nonindex mutation carriers. Germline CDC73 analysis is recommended in individuals with (suspected) HPT-JT syndrome, familial isolated pHPT, atypical or malignant parathyroid histology, and young individuals with pHPT. These criteria would increase germline CDC73 mutation detection, enabling optimal clinical management of pHPT as well as genetic counseling and surveillance for family members at risk for developing CDC73-related disorders.

Molecular genetics of syndromic and non-syndromic forms of parathyroid carcinoma.

Parathyroid carcinoma (PC) may occur as part of a complex hereditary syndrome or an isolated (i.e., non‐syndromic) non‐hereditary (i.e., sporadic) endocrinopathy. Studies of hereditary and syndromic forms of PC, which include the hyperparathyroidism‐jaw tumor syndrome (HPT‐JT), multiple endocrine neoplasia types 1 and 2 (MEN1 and MEN2), and familial isolated primary hyperparathyroidism (FIHP), have revealed some genetic mechanisms underlying PC. 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. Moreover, CDC73 germline mutations occur in 20%–40% of patients with sporadic PC and may reveal unrecognized HPT‐JT. This indicates that CDC73 mutations are major driver mutations in the etiology of PCs. However, there is no genotype–phenotype correlation and some CDC73 mutations (e.g., c.679_680insAG) have been reported in patients with sporadic PC, HPT‐JT, or FIHP. Other genes involved in sporadic PC include germline MEN1 and rearranged during transfection (RET) mutations and somatic alterations of the retinoblastoma 1 (RB1) and tumor protein P53 (TP53) genes, as well as epigenetic modifications including DNA methylation and histone modifications, and microRNA misregulation. This review summarizes the genetics and epigenetics of the familial syndromic and non‐syndromic (sporadic) forms of PC.

Large intragenic deletion of CDC73 (exons 4\u201310) in a three-generation hyperparathyroidism-jaw tumor (HPT-JT) syndrome family

BackgroundInactivating mutations of CDC73 cause Hyperparathyroidism-Jaw Tumour syndrome (HPT-JT), Familial Isolated Hyperparathyroidism (FIHP) and sporadic parathyroid carcinoma. We conducted CDC73 mutation analysis in an HPT-JT family and confirm carrier status of the proband’s daughter.MethodsThe proband had primary hyperparathyroidism (parathyroid carcinoma) and uterine leiomyomata. Her father and daughter had hyperparathyroidism (parathyroid adenoma) but no other manifestations of HPT-JT. CDC73 mutation analysis (sequencing of all 17 exons) and whole-genome copy number variation (CNV) analysis was done on leukocyte DNA of the three affecteds as well as the proband’s unaffected sister.ResultsA novel deletion of exons 4 to 10 of CDC73 was detected by CNV analysis in the three affecteds. A novel insertion in the 5’UTR (c.-4_-11insG) that co-segregated with the deletion was identified. By in vitro assay the 5’UTR insertion was shown to significantly impair the expression of the parafibromin protein. Screening for the mutated CDC73 confirmed carrier status in the proband’s daughter and the biochemistry and ultrasonography led to pre-emptive surgery and resolution of the hyperparathyroidism.ConclusionsA novel gross deletion mutation in CDC73 was identified in a three-generation HPT-JT family emphasizing the importance of including screening for large deletions in the molecular diagnostic protocol.

Specifying the molecular pattern of sporadic parathyroid tumorigenesis—The Y282D variant of the GCM2 gene

ObjectiveSporadic carcinoma of the parathyroid glands is a rare malignant neoplasia. The GCM2 gene encodes a transcription factor that is crucial to embryonic parathyroid development. The Y282D variant of GCM2 exhibits increased transcriptional activity, and the presence of this variant is significantly associated with a higher prevalence of primitive hyperparathyroidism. The present study investigated the prevalence of the Y282D variant of the GCM2 gene and its association with clinical parameters in patients with a definitive histological diagnosis of sporadic parathyroid carcinoma (SPC) or atypical adenoma (AA).

Genomic profiling reveals mutational landscape in parathyroid carcinomas.

Parathyroid carcinoma (PC) is an extremely rare malignancy lacking effective therapeutic intervention. We generated and analyzed whole-exome sequencing data from 17 patients to identify somatic and germline genetic alterations. A panel of selected genes was sequenced in a 7-tumor expansion cohort. We show that 47% (8 of 17) of the tumors harbor somatic mutations in the CDC73 tumor suppressor, with germline inactivating variants in 4 of the 8 patients. The PI3K/AKT/mTOR pathway was altered in 21% of the 24 cases, revealing a major oncogenic pathway in PC. We observed CCND1 amplification in 29% of the 17 patients, and a previously unreported recurrent mutation in putative kinase ADCK1. We identified the first sporadic PCs with somatic mutations in the Wnt canonical pathway, complementing previously described epigenetic mechanisms mediating Wnt activation. This is the largest genomic sequencing study of PC, and represents major progress toward a full molecular characterization of this rare malignancy to inform improved and individualized treatments.

CDC73 gene mutations in sporadic ossifying fibroma of the jaws.

BackgroundThe tumor suppressor gene CDC73 was found to be associated with hyperparathyroidism-jaw tumor syndrome (HPT-JT), which is characterized by parathyroid adenoma or carcinoma, ossifying fibroma (OF) of the jaws, and renal and uterine lesions. Mutations in CDC73 have also been frequently detected in sporadic parathyroid carcinomas and renal tumors. However, the prevalence and range of CDC73 mutations in sporadic OFs have not been established.MethodsWe directly sequenced coding and flanking splice junctional regions of CDC73 in 40 cases of sporadic OF of the jaws. We also used immunohistochemistry to detect parafibromin, the protein product of CDC73, in those cases.ResultsTwo novel CDC73 mutations were identified in 2 of the 40 cases (5 %). Both were somatic mutations located in exon 1 of the coding region. Strong parafibromin expression was detected in all 40 cases, irrespective of the presence of CDC73 mutations.ConclusionsMutations inCDC73 were rare in sporadic OF of the jaws, but may affect the pathogenesis of a small subset of tumors of this type.