CDC73 Mutation Research Articles

Parathyroid carcinoma during pregnancy: a novel pathogenic CDC73 mutation – a case report

BackgroundParathyroid carcinoma is an uncommon cause of PTH-dependent hypercalcemia. Only a handful of cases have been reported of parathyroid carcinoma during pregnancy.Case presentationTwenty-four – Year – old female presented with proximal myopathy was found to have hypercalcemia. Her serum corrected total calcium was – 15 mg/dl (8.5 – 10.3), serum phosphate – 2.3 mg/dl (2.5 – 4.5), intact PTH – 118 pg/ml (20 – 80), Vitamin D – 15 ng/ml and Urine Ca/Cr ratio – 2.1 (0.1 – 0.2). Her CECT–neck revealed a well-defined mass lesion posterior to the right lobe of the thyroid – 2.6 cm × 2.5 cm × 2.9 cm in size. She was started on vitamin D supplementation, and she underwent right lower focal parathyroidectomy. Her PTH levels normalized following surgery. Her histology revealed an atypical parathyroid adenoma. She was treated with calcium and vitamin D. Her follow up was uneventful.One year following initial surgery the patient became pregnant and at 16 weeks of POA, the patient presented with a rapidly enhancing neck mass for one week duration. Her biochemical investigations were suggestive of a recurrence of primary hyperparathyroidism. Her ultrasound scan of the neck revealed a well-defined discreate hypoechoic nodule, superior to the thyroid isthmus which was confirmed by a non-contrast MRI scan of the neck. She underwent an uncomplicated second trimester parathyroid tumour excision with normalization of post op PTH. Her histology revealed a parathyroid carcinoma with vascular and capsular invasion. Her genetic studies revealed a novel frameshift mutation of the CDC73 gene. She was treated with calcium and vitamin D supplementation and closely followed up with ionized calcium and PTH levels which were normal throughout the pregnancy. She had an uncomplicated caesarean section at a POA of 37 weeks. Currently she is twelve weeks post-partum, in remission of disease.ConclusionThis case shows the importance of stringent follow up of atypical parathyroid adenoma patients, the benefit of second trimester surgery in management of hypercalcemia due to parathyroid carcinoma during pregnancy and the importance of identifying the novel CDC73 gene mutation.

The roles of the tumor suppressor parafibromin in cancer.

In this review, we discuss parafibromin protein, which is encoded by CDC73. A mutation in this gene causes hyperparathyroidism-jaw tumor (HPT-JT) syndrome, an autosomal dominant disease. CDC73 is transcriptionally downregulated by the Wilms’ tumor suppressor gene WT1 and translationally targeted by miR-182-3p and miR-155. In the nucleus, parafibromin binds to RNA polymerase II and PAF1 complex for transcription. Parafibromin transcriptionally increases the expression of c-Myc, decreases CPEB1 expression by interacting with H3M4, and reduces cyclin D1 expression by binding to H3K9. The RNF20/RNF40/parafibromin complex induces monoubiquitination of H2B-K120, and SHP2-mediated dephosphorylation of parafibromin promotes the parafibromin/β-catenin interaction and induces the expression of Wnt target genes, which is blocked by PTK6-medidated phosphorylation. Parafibromin physically associates with the CPSF and CstF complexes that are essential for INTS6 mRNA maturation. In the cytosol, parafibromin binds to hSki8 and eEF1Bγ for the destabilization of p53 mRNA, to JAK1/2-STAT1 for STAT1 phosphorylation, and to actinin-2/3 to bundle/cross-link actin filaments. Mice with CDC73 knockout in the parathyroid develop parathyroid and uterine tumors and are used as a model for HPT-JT syndrome. Conditional deletion of CDC73 in mesenchymal progenitors results in embryos with agenesis of the heart and liver while its abrogation in mature osteoblasts and osteocytes increases cortical and trabecular bone. Heterozygous germline mutations in CDC73 are associated with parathyroid carcinogenesis. The rates of CDC73 mutation and parafibromin loss decrease from parathyroid adenoma to atypical adenoma to carcinoma. In addition, down-regulated parafibromin is closely linked to the tumorigenesis, subsequent progression, or poor prognosis of head and neck, gastric, lung, colorectal, and ovarian cancers, and its overexpression might reverse the aggressiveness of these cancer cells. Therefore, parafibromin might be useful as a biological marker of malignancies and a target for their gene therapy.

Association Between Parafibromin Expression and Presence of Brown Tumors and Jaw Tumors in Patients with Primary Hyperparathyroidism: Series of Cases with Review of the Literature

BACKGROUND Brown and jaw tumors are rare entities of poorly understood etiology that are regarded as end-stage of bone remodeling in patients with long-lasting and chronic hyperparathyroidism. Jaw tumors are mainly diagnosed in jaw tumors syndrome (HPT-JT syndrome) and are caused by mutation in the CDC73 gene, encoding parafibromin, a tumor suppressing protein. The aim of this work is to present 4 cases of patients in whom the genetic mutation of the CDC73 gene and clinical presentation coexist in an unusual setting that has not yet been described. CASE REPORT We present cases of 4 patients with primary hyperparathyroidism. Three were diagnosed with brown tumors (located in long bones, ribs, iliac, shoulders) and 1 with brown and jaw tumors. Expression of parafibromin in affected parathyroid tissues were analyzed. In patients without positive parafibromin staining, we searched for CDC73 mutation using next-generation sequencing. Parafibromin staining was positive in 1 patient with brown tumors and was negative in 2 individuals with brown tumors and 1 with brown and jaw tumors. CDC73 mutation was detected in two-thirds of patients (60%) with negative staining for parafibromin and brown tumors. MEN1 mutation was found in the patient with brown tumor and positive staining for parafibromin. CONCLUSIONS Patients with hyperparathyroidism and coexistence of brown tumors or jaw tumors might have decreased expression of parafibromin in parathyroid adenoma tissue, which might be caused by CDC73 mutation and suggest a genetic predisposition. Further research on much larger study groups is needed.

Off-label use of cinacalcet in pediatric primary hyperparathyroidism: A French multicenter experience.

BackgroundCinacalcet is a calcimimetic approved in adults with primary hyperparathyroidism (PHPT). Few cases reports described its use in pediatric HPT, with challenges related to the risk of hypocalcemia, increased QT interval and drug interactions. In this study, we report the French experience in this setting.MethodsWe retrospectively analyzed data from 18 pediatric patients from 7 tertiary centers who received cinacalcet for PHPT. The results are presented as median (interquartile range).ResultsAt a median age of 10.8 (2.0–14.4) years, 18 patients received cinacalcet for primary HPT (N = 13 inactive CASR mutation, N = 1 CDC73 mutation, N = 1 multiple endocrine neoplasia type 1, N=3 unknown etiology). Cinacalcet was introduced at an estimated glomerular filtration rate (eGFR) of 120 (111–130) mL/min/1.73 m2, plasma calcium of 3.04 (2.96–3.14) mmol/L, plasma phosphate of 1.1 (1.0–1.3) mmol/L, age-standardized (z score) phosphate of −3.0 (−3.5;−1.9), total ALP of 212 (164–245) UI/L, 25-OHD of 37 (20–46) ng/L, age-standardized (z score) ALP of −2.4 (−3.7;−1.4), PTH of 75 (59–123) ng/L corresponding to 1.2 (1.0–2.3)-time the upper limit for normal (ULN). The starting daily dose of cinacalcet was 0.7 (0.6–1.0) mg/kg, with a maximum dose of 1.0 (0.9–1.4) mg/kg per day. With a follow-up of 2.2 (1.3–4.3) years on cinacalcet therapy, PTH and calcium significantly decreased to 37 (34–54) ng/L, corresponding to 0.8 (0.5–0.8) ULN (p = 0.01), and 2.66 (2.55–2.90) mmol/L (p = 0.002), respectively. In contrast, eGFR, 25-OHD, ALP and phosphate and urinary calcium levels remained stable. Nephrocalcinosis was not reported but one patient displayed nephrolithiasis. Cinacalcet was progressively withdrawn in three patients; no side effects were reported.ConclusionsCinacalcet in pediatric HPT can control hypercalcemia and PTH without significant side effects.

Immunohistochemical Profile of Parathyroid Tumours: A Comprehensive Review

Immunohistochemistry remains an indispensable tool in diagnostic surgical pathology. In parathyroid tumours, it has four main applications: to detect (1) loss of parafibromin; (2) other manifestations of an aberrant immunophenotype hinting towards carcinoma; (3) histogenesis of a neck mass and (4) pathogenetic events, including features of tumour microenvironment and immune landscape. Parafibromin stain is mandatory to identify the new entity of parafibromin-deficient parathyroid neoplasm, defined in the WHO classification (2022). Loss of parafibromin indicates a greater probability of malignant course and should trigger the search for inherited or somatic CDC73 mutations. Aberrant immunophenotype is characterised by a set of markers that are lost (parafibromin), down-regulated (e.g., APC protein, p27 protein, calcium-sensing receptor) or up-regulated (e.g., proliferation activity by Ki-67 exceeding 5%) in parathyroid carcinoma compared to benign parathyroid disease. Aberrant immunophenotype is not the final proof of malignancy but should prompt the search for the definitive criteria for carcinoma. Histogenetic studies can be necessary for differential diagnosis between thyroid vs. parathyroid origin of cervical or intrathyroidal mass; detection of parathyroid hormone (PTH), chromogranin A, TTF-1, calcitonin or CD56 can be helpful. Finally, immunohistochemistry is useful in pathogenetic studies due to its ability to highlight both the presence and the tissue location of certain proteins. The main markers and challenges (technological variations, heterogeneity) are discussed here in the light of the current WHO classification (2022) of parathyroid tumours.

Parathyroid carcinoma: Single centre experience.

Parathyroid Carcinoma is a rare malignant neoplasm, accounting for less than 1% of primary hyperparathyroidism cases. Parathyroid carcinomas are characterized by markedly elevated levels of PTH, severe hypercalcemia and established target organ damage. The authors report the experience of a single centre regarding the management and outcome of patients with parathyroid carcinomas and revise relevant literature. Retrospective review of all patients with parathyroid carcinoma evaluated at a tertiary oncologic centre from 1991 until 2021. Seventeen patients were identified (10 males), with a mean age at diagnosis of 53 ± 16 years and a median follow-up of 16.5 years. Most patients presented with hypercalcemia (n = 15), with a mean serum calcium concentration of 13.5 mg/dl (9.6-16.5) and mean PTH of 1173 pg/ml (276-2500). Hyperparathyroidism-mediated organ damage was observed in most patients (n = 16), with predominant renal (n = 12) and skeletal (n = 9) complications. En bloc surgical resection was performed in nine patients. Three patients underwent adjuvant radiotherapy. Recurrence was observed in 8 cases (47.1%) after a median of 24 months following surgery and no independent predictors of recurrence were identified. The overall survival and disease specific survival at 5-year was 88% and 94%, respectively. CDC73 mutations were present in 38.5% of analysed patients and one patient was diagnosed with MEN1. Parathyroid carcinoma is associated with a significant rate of recurrence and limited effective treatment beyond initial complete surgical resection. Therefore, preoperatively high index of suspicion is paramount to optimize patient care. This is, to our knowledge, the largest Portuguese cohort published so far.

A novel long-range deletion spanning CDC73 and upper-stream genes discovered in a kindred of familial primary hyperparathyroidism.

To confirm the exact break-point of a novel long-range deletion discovered in one female parathyroid carcinoma (PC) patient who has a strong family history suggesting familial hyperparathyroidism, and to investigate the expression of parafibromin in the patient's affected lesion. Clinical information of one female patient as well as five of her relatives was collected. Their genomic DNA extracted from peripheral blood went through Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA). After completing whole genome sequencing (WGS), clone sequencing was also performed, whose result was aligned with standard human genome database after Sanger sequencing. The medical history of recurrent hypercalcemia after parathyroidectomy and histopathological investigation confirmed that the female patient was diagnosed with PC. WGS displayed a novel 130 kb long-range deletion spanning UCHL5 to CDC73 that was later confirmed by clone sequencing. MLPA showed similar results in four of her five relatives, suggesting these people to be carriers of the same long-range deletion, and three among them had a history of primary hyperparathyroidism (PHPT) ahead of the proband's first visit. We discovered a novel 130 kb long-range deletion spanning CDC73 in a family of 5 persons, and the existence of the deletion was related to PHPT and PC. Our discovery validated the role of CDC73 mutation in the occurrence of PHPT and PC, which provided new information to the genetic studies of PC.

Do Patients With Atypical Parathyroid Adenoma Need Close Follow-up?

Atypical parathyroid adenomas (APAs) are neoplasms with uncertain malignant potential but lack unequivocal histological signs of malignancy. This work aims to retrospectively evaluate the clinical and biochemical profiles of patients with APA, the outcome after parathyroidectomy (PTX), and the presence of CDC73 germline and somatic mutations. This monocentric study was conducted on consecutive patients undergoing PTX for primary hyperparathyroidism (PHPT) between June 2000 and December 2020. Fifty-eight patients with a confirmed histopathological diagnosis of APA, and age- and sex-matched controls with parathyroid adenoma (PA) were also included. Fifty-four patients had sporadic PHPT and 4 had familial isolated hyperparathyroidism (FIHP). Thirty-four patients (59%) had symptomatic disease. Serum calcium and parathyroid hormone (PTH) levels were significantly higher in symptomatic compared to asymptomatic patients (P = .048 and .008, respectively). FIHP patients were younger than their sporadic counterparts (30 ± 17 years vs 55 ± 13 years). APA patients had significantly higher serum calcium and PTH levels and lower 25-hydroxyvitamin D concentration, bone mineral density, and T score at one-third distal radius compared to those with PA. Four of 56 APA patients displayed a CDC73 germline mutation. No somatic CDC73 mutation was identified in 24 tumor specimens. The mean follow-up after surgery was 60 ± 56.4 months. All but 6 patients (90%), 5 with apparently sporadic PHPT and 1 with FIHP, were cured after surgery. The large majority of patients with APA, despite a moderate/severe phenotype, have a good prognosis. Germline CDC73 mutation-positive patients had a higher rate of persistent/recurrent disease. CDC73 gene alterations do not seem to have a relevant role in the tumorigenesis of sporadic APA.

Parafibromin Abnormalities in Ossifying Fibroma.

Ossifying fibromas are very rare tumors that are sometimes seen as part of the hyperparathyroidism-jaw tumor syndrome (HPT-JT), which is caused by inactivating mutations of the HRPT2/CDC73 tumor suppressor gene. CDC73 mutations have been identified in a subset of sporadic cases but aberrant expression of the encoded protein, parafibromin, has not been demonstrated in ossifying fibroma. We sought to determine if loss of parafibromin regularly contributes to the development of sporadic, nonsyndromic ossifying fibroma. We examined a series of 9 ossifying fibromas, including ossifying, cemento-ossifying, and juvenile active variants, for parafibromin protein expression by immunohistochemistry and for CDC73 sequence abnormalities by Sanger sequencing and/or targeted AmpliSeq panel sequencing. Four ossifying fibromas showed a complete absence of nuclear parafibromin expression; loss of parafibromin expression was coupled with aberrant cytoplasmic parafibromin expression in 1 case. CDC73 mutations were detected in 2 cases with aberrant parafibromin expression. These results provide novel evidence, at the level of protein expression, that loss of the parathyroid CDC73/parafibromin tumor suppressor may play a role in the pathogenesis of a subset of ossifying fibromas.

Comparative Transcriptomic Profiling Revealed Distinctive Patterns in Differentially Expressed Genes Related to Clinicopathologic Features of Parathyroid Carcinoma and Adenoma

Parathyroid carcinoma is a rare malignancy which remains as a clinical unmet need lacking effective therapeutic intervention. (1) In this study, we compared mutational profile of parathyroid carcinoma, adenoma, and normal parathyroid tissue using RNA-Seq based transcriptomics analysis and whole exome sequencing. A total of 40 parathyroid specimens [parathyroid carcinoma (n=8), adenoma (n=24), and normal tissue incidentally obtained from thyroidectomy for various reasons (n=8)] from 39 individuals (women n=34, 87%; mean age 51 year) were analyzed. Compared to adenoma and normal parathyroid groups, parathyroid carcinoma group had younger age (carcinoma 35 ± 12 vs. other 56 ± 16 year, p=0.001) and higher serum parathyroid hormone (PTH; 231 [145–474] vs. 114 [88–196] vs. 34 [29–41] pg/mL, p=0.001) prior to surgery. CDC73 mutation was found in 7 of 8 carcinoma specimens, which harbored germline mutation in 6 of them. Among top feature gene mutations for classifying adenoma and carcinoma, carcinoma-specific genes showed high specificity, whereas adenoma-related key features were largely overlapped with normal tissues. Transcriptional profiling revealed 546 carcinoma-specific differentially expressed genes (DEGs), 135 adenoma-specific DEGs, and 323 common DEGs. Hierarchical clustering with 546 carcinoma-specific DEGs detected four clusters with distinctive clinicopathologic characteristics (cluster 1 [n=12]: 7 normal tissues and 5 adenomas; cluster 2 and 3 [n=22]: all adenomas except one normal tissue; cluster 4 [n=9]: all parathyroid carcinomas except one adenoma). Carcinoma-specific DEGs include upregulation of GRIN2A, LYPD1, and SOX2 and downregulation of ENTPPL, MYO3B, and PIK3C2G. Gene ontology enrichment revealed that these DEGs were mainly involved in the binding of cell adhesion molecule, actin, and Rho GTPase, and extracellular matrix structural constituent. Two adenoma clusters significantly differed in urinary calcium excretion level (403 [312–488] vs. 205 [150–327], p=0.037) without significant differences in median PTH (102 [86–138] vs. 125 [92–229] pg/mL) and calcium level (11.1 ± 1.0 vs. 11.0 ± 0.9 mg/dL; P>0.05 for all). In summary, parathyroid carcinoma had distinctive transcriptional profiles which might improve the early detection of parathyroid carcinoma. Parathyroid adenomas were clustered into two groups with regard to urinary calcium excretion level based on transcriptional profiles, which merits further investigation. Reference: (1) Pandya C et al., JCI Insight. 2017 Mar 23; 2(6): e92061. Sources of Research Support: This study was supported by Severance Hospital Research Fund for Clinical Excellence (SHRC C-2019-0032; C-2020-0035).

Ectopic Atypical Parathyroid Adenoma Presenting With Pancreatitis

Background: Atypical Parathyroid Adenoma (APA) and parathyroid carcinomas (PC) are rare parathyroid tumors (<1%) causing primary hyperparathyroidism. We present a case of ectopic APA in the left anterior mediastinum. Case: A 38 year old male with hyperlipidemia admitted for acute pancreatitis noted to have calcium level of 13.4 mg/dl (8.6–10.3mg/dl) in the absence of family history of hypercalcemia or kidney stones. He was treated with zoledronic acid, intravenous fluids and calcitonin for hypercalcemia. Pancreatitis resolved with fluid management. Calcium on discharge was 9.9 mg/dl. 8 week follow-up labs showed PTH of 420 pg/ml (14–64 pg/ml), calcium 10.2 mg/dl, phosphorus 1.9 mg/dl (2.5–4.5 mg/dl), vitamin D 19 ng/ml (30–100 ng/ml), 24-hour urinary calcium 115 mg/24 hour (55–300 mg/24 hour) and calcium to creatinine ratio 0.41. Hence diagnosis of primary hyperparathyroidism was made but given the degree of calcium and PTH elevation there was a concern for PC. Ultrasound of the neck demonstrated no abnormality. Sestamibi scan showed irregular focal accumulation of radiotracer in the left upper mediastinum suggestive of mediastinal ectopic parathyroid adenoma (EPA). CT chest with contrast showed a 3.9 x 2.2 x 3.4cm lobulated, heterogenous, hypodense, minimally enhancing mass in the left anterior prevascular space. Diagnosis of EPA was made and he underwent left video assisted thoracic surgery. Operative findings showed a multilobular mass at the level of the aortic arch between vagus and phrenic nerves. Intraoperative PTH went from 1124 pg/ml pre-incision to 160 at 15-minute post-excision. Postoperative calcium was 9.6 mg/dl and PTH 51 pg/ml. Final pathology showed 3.7 x 2.5 x 2cm, hypercellular parathyroid with prominent fibrous band and parafibromin retention compatible with APA. Discussion: APA is an intermediate form of parathyroid neoplasm with uncertain malignant potential, showing atypical histological features without evidence of invasive growth. This poses a diagnostic challenge of PC as the histopathological features overlap and requires an expert pathologist to make the diagnosis. Inactivating CDC73 mutations, encoding parafibromin, is the most common genetic abnormality. Loss of parafibromin has been seen in 100% cases of PC and predicts poor prognosis. Due to rarity of the disease there are no clear guidelines on follow up. Based on literature, annual follow up is suggested with biochemical testing and imaging for the first 5 years after surgery and every 2–3 years thereafter due to 3% recurrence rate and potential progression to PC. Cetani et al in 2019 reported 672 cases of APA, only 3 were ectopic in the mediastinum thus making our case rare. APA is a rare entity as biochemical profile and histopathological features overlap with PC and can be misdiagnosed. Greater awareness of APA may improve capture of cases, allowing the development of guidelines to recognize and treat it.

Genotype of CDC73 germline mutation determines risk of parathyroid cancer.

Mutation of the CDC73 gene, which encodes parafibromin, has been linked with parathyroid cancer. However, no correlation between genotypes of germline CDC73 mutations and the risk of parathyroid cancer has been known. In this study, subjects with germline CDC73 mutations were identified from the participants of two clinical protocols at National Institutes of Health (Discovery Cohort) and from the literature (Validation Cohort). The relative risk of developing parathyroid cancer was analyzed as a function of CDC73 genotype, and the impact of representative mutations on structure of parafibromin was compared between genotype groups. A total of 419 subjects, 68 in Discovery Cohort and 351 in Validation Cohort, were included. In both cohorts, percentages of CDC73 germline mutations that predicted significant conformational disruption or loss of expression of parafibromin (referred as 'high-impact mutations') were significantly higher among the subjects with parathyroid cancers compared to all other subjects. The Kaplan-Meier analysis showed that high-impact mutations were associated with a 6.6-fold higher risk of parathyroid carcinoma compared to low-impact mutations, despite a similar risk of developing primary hyperparathyroidism between two groups. Disruption of the C-terminal domain (CTD) of parafibromin is directly involved in predisposition to parathyroid carcinoma, since only the mutations impacting this domain were associated with an increased risk of parathyroid carcinoma. Structural analysis revealed that a conserved surface structure in the CTD is universally disrupted by the mutations affecting this domain. In conclusion, high-impact germline CDC73 mutations were found to increase risk of parathyroid carcinoma by disrupting the CTD of parafibromin.

The genomic profile of parathyroid carcinoma based on whole-genome sequencing.

Parathyroid carcinoma (PC) is a rare endocrine malignancy with poor outcomes. Although some mutations such as CDC73 have been found in patients, the molecular mechanism of PC still needs extensive data to clarify. Whole-genome sequencing (WGS) was performed with frozen samples from 23 PC patients. Peripheral leukocytes were collected from 14 patients and served as controls. Somatic and germline gene alterations, copy number abnormalities and structural variants were detected. Inactivating CDC73 mutations were identified in 39.1% of patients, but only one germline inactivating mutation was found. Other cancer-related mutations identified in more than one case were MAF (2/23), NEB (6/23), NCOR1 (2/23), TTK (2/23), GRIN3A (4/23), TRIO (2/23), MAP1B (2/23), TJP2 (2/23) and FAM20A (2/23). In the seven wild-type CDC73 samples, the mutated genes were enriched in pathways involving antigen presentation, allograft rejection or autoimmune disease. More copy number variants were found in patients with cancer recurrence (P = .006) and CDC73 mutations (P = .022) than in those without these characteristics. PIK3CA loss was found in one sample, which also harboured a CDC73 mutation. Gene alterations in the PI3K/AKT/mTOR pathway were found in 78.3% (18/23) of tumours. The most prominent cancer-predisposing mutations were PDE4DIP (15/23), MAP3K1 (13/23) and CDC42EP1 (10/23). In conclusion, the PI3K/AKT/mTOR pathway may be pivotal in PC. CDC73 mutation correlated with an increased mutational burden and tumour relapse. PC patients with wild-type CDC73 harboured mutations relevant to antigen presentation and autoimmune diseases. A molecular classification based on the CDC73 mutation may help to manage follow-up and therapy for PC patients.

SUN-LB132 Frequency and Impact of Mutations in Tumor Suppressor Gene CDC73 in General Population and Malignant Tumors

Background: CDC73 gene is a putative tumor suppressor gene, and somatic and germline mutations of this gene have been linked with parathyroid tumors. There are also some reports suggesting that germline CDC73 mutations may increase risk of jaw, kidney and uterine tumors. However, the incidence and significance of CDC73 somatic mutations is largely unknown in tumors other than parathyroid tumors. Methods/Design: 1) Assess CDC73 germline mutation frequency and genotypes in general population using ExAC (Exome Aggregation Consortium) and gnomAD (Genome Aggregation Database); 2) Assess CDC73 somatic mutation frequency in various type of tumors using the Cancer Genome Atlas (TCGA) and non-TCGA datasets; 3) Examine significance of CDC73 mutation in uterine endometrial carcinoma (UCEC). Overall survival, CDC73 mutation signature, gene expression profile (GEP) and tumor immune microenvironment were compared between the UCEC samples with and without CDC73 mutations. Results: In ExAC and gnomAD databases, most of CDC73 germline mutations were mapped to the intron regions of the CDC73 gene and nonsynonymous CDC73 mutations are very rare, with allele frequency ranging from 8.24e-06 to 9.92e-05 and 3.97e-06 to 7.43e-05, respectively. Missense mutations accounted for more than 95% of the nonsynonymous mutations in the CDC73 gene in both databases. 2) In 155 cancer genomics studies including both TCGA and non-TCGA datasets with no overlapping samples, CDC73 was mutated in 0.7% cases and missense mutations comprised 78% of the CDC73 mutations. CDC73 somatic mutations were undetected or rarely detected in endocrine tumors except for parathyroid tumors. 3) UCEC is the tumor type that has the second highest CDC73 somatic mutation rate (8%) after parathyroid tumors. The UCEC with CDC73 mutations had a significantly better overall survival with a logrank p-value of 0.033 compared to the tumors with CDC73 WT. GEP analysis revealed that the CDC73-mutated UCEC tumors had significant upregulation of immunological markers and enriched immunologic signature compared to the CDC73-WT tumors. In silico analysis of tumor immune microenvironment showed higher fractions of cytotoxic CD8 cells, T follicular helper cells and M1 macrophage in the CDC73-mutated UCEC tumors. The majority of the CDC73-mutated tumors were POLE ultra-mutated and microsatellite instability (MSI) subtypes, which likely account for a better survival and an increased immune-cell infiltrate of these tumors. Conclusion: CDC73 mutations is rare in general population and tumors except for parathyroid carcinoma and UCEC. CDC73 mutation is a marker for better prognosis in UCEC and is associated with increased immune cell infiltrate in tumor microenvironment, likely due to majority of the CDC73-mutated tumors were POLE ultra-mutated and microsatellite instability (MSI) subtypes.

In silico analysis of CDC73 gene revealing 11 novel SNPs with possible association to Hyperparathyroidism-Jaw Tumor syndrome

Abstract Hyperparathyroidism-Jaw Tumor (HPT-JT) is an autosomal dominant disorder with variable expression, with an estimated prevalence of 6.7 per 1,000 population. Genetic testing for predisposing CDC73 (HRPT2) mutations has been an important clinical advance, aimed at early detection and/or treatment to prevent advanced disease. The aim of this study is to assess the most deleterious SNPs mutations on CDC73 gene and to predict their influence on the functional and structural levels using different bioinformatics tools. Method: Computational analysis using twelve different in-silico tools including SIFT, PROVEAN, PolyPhen-2, SNAP2, PhD-SNP, SNPs&amp;GO, P-Mut, I-Mutant ,Project Hope, Chimera, COSMIC and dbSNP Short Genetic Variations were used to identify the impact of mutations in CDC73 gene that might be causing jaw tumor. Results: From (733) SNPs identified in the CDC73 gene we found that only Eleven SNPs (G49C, L63P, L64P, D90H, R222G, W231R, P360S, R441C, R441H, R504S and R504H) has deleterious effect on the function and structure of protein and expected to cause the syndrome. Conclusion: Eleven substantial genetic/molecular aberrations in CDC73 gene identified that could serve as diagnostic markers for hyperparathyroidism-jaw tumor (HPT-JT).

Clinical MEN-1 Among a Large Cohort of Patients With Acromegaly.

ContextClinical multiple endocrine neoplasia type 1 (MEN-1) is diagnosed by the presence of at least 2 MEN-1–associated tumors. Many patients with acromegaly and clinical MEN-1 yield negative testing for MEN1 mutations. While cases of acromegaly and primary hyperparathyroidism (PHP) with negative genetic testing have been reported, its prevalence among patients with acromegaly is undetermined, and the clinical presentation has not been well characterized.ObjectivesThe main goals of this study are: (1) To determine the prevalence of clinical MEN-1 with PHP in patients with acromegaly and characterize their clinical features; and (2) to evaluate the genetic basis for the coexistence of acromegaly and PHP.DesignRetrospective record review and genetic analysis.SettingClinical Research Centers.Participants414 patients with acromegaly.InterventionsClinical evaluation and DNA sequencing for MEN1, CDKN1A, CDKN1B, CDKN2B, CDKN2C, and AIP genes.Main outcome measurementsClinical and genetic analysis.ResultsAmong patients with acromegaly, clinical MEN-1, as defined by the presence of at least one other MEN-1-associated tumor, was present in 6.6%. PHP occurred in 6.1%; more than half had parathyroid hyperplasia. DNA sequencing was unrevealing for genetic mutations, except for 1 case of a CDC73 mutation. Acromegaly was diagnosed at an older age with a higher prevalence of malignancies (specifically breast and thyroid) in patients with coexisting PHP than those with isolated acromegaly.ConclusionsA distinct phenotype is described in patients with clinical MEN-1 and negative genetic testing for mutations previously associated with this syndrome. Further studies are needed to identify other genes that may explain the association between PHP and acromegaly.

Prognostic role of parafibromin staining and CDC73 mutation in patients with parathyroid carcinoma: A systematic review and meta-analysis based on individual patient data.

Parathyroid carcinoma (PC) is a rare malignant neoplasm with a relatively poor prognosis. The loss of parafibromin expression or the presence of CDC73 mutation has been found to be remarkably associated with malignancy in parathyroid tumours. However, the prognostic role of them in PC has not yet been shown due to sampling limitations. We conducted a systematic review and meta-analysis based on individual patient data to clarify the performance of parafibromin immunohistochemical staining and CDC73 gene sequencing in predicting outcomes for patients PC. Published studies from PubMed/MEDLINE, EMBASE, Cochrane and Scopus Databases were searched using the terms 'parafibromin', 'CDC73', 'HRPT2' and 'parathyroid' to identify eligible studies. From the included studies, the survival data of patients with PC were extracted, and a Cox proportional hazards model was used to assess hazard ratio (HR)fordisease-free survival (DFS) and overall survival (OS). A total of 193 patients from 9 studies were included in this survival analysis. Negative immunohistochemical staining of parafibromin was shown to be a risk factor for recurrence/metastasis (HR 2.73, P=.002) and death (HR 2.54, P=.004). Patient age≥50years was significantly related to lower OS (HR 2.37, P=.004) but not to DFS. CDC73 mutation was not statistically related to DFS or OS. Negative parafibromin staining indicated a higher risk of recurrence/metastasis and mortality. The immunohistochemical staining of parafibromin seems to be more promising in predicting outcomes for patients with PC than the sequencing of CDC73.

289O - Spectrum of mitochondrial genomic variation in parathyroid neoplasms by ultra-deep targeted DNA sequencing

BackgroundParathyroid neoplasms are characterized with hypersecretion of parathyroid hormone and potentially exhibit disruption of metabolic pathways. Mitochondria are essential for energy homeostasis and mitochondrial DNA (mtDNA) abnormalities are related to multiple types of malignancies. However, the status of mtDNA mutation and copy number variations in parathyroid carcinoma (PC) is not well known. MethodsUltra-deep targeted sequencing of mitochondrial genome was performed using tissues of 12 PCs and 12 parathyroid adenomas (PAs). Germline variants and somatic mutations in the mitochondrial genome were scanned and analysed in comparison with clinical features. The relative copy number of mtDNA in PCs and PAs was determined via quantitative real-time polymerase chain reaction. ResultsA total of 528 germline variants and 16 somatic mutations were identified in 24 samples of parathyroid neoplasms. All 62 non-synonymous germline variants in coding sequence (CDS) were predicted to be of low pathogenicity in PA and PC samples. Five somatic mutations with high pathogenicity in CDSs were identified in 4 (33.3%, 4/12) PC samples and 1 PA sample (8.3%, 1/12). A somatic mutation in a CDS was correlated with high mtDNA copy number in parathyroid neoplasm (p = 0.004), CDC73 gene mutation (p = 0.017) and PC recurrence (p = 0.024). More C-19 genotypes in the D310 region were found in PA than in the PC samples (3.5% vs 1.9%, p = 0.045). ConclusionsMore somatic CDS mutations with high pathogenicity were identified in PC than in PA. A high mtDNA copy number was found in parathyroid neoplasms with somatic CDS mutations and in PCs with CDC73 mutations and recurrence. Legal entity responsible for the studyThe authors. FundingThis work was supported by the Chinese Academy of Medical Sciences (CAMS) Initiative for Innovative Medicine (CAMS-I2M) (2017-I2M-1-001), Peking Union Medical College Innovative Team Development Program, the Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences (2018PT32014) and the 2016 Peking Union Medical College Hospital Science Foundation for Junior Faculty (pumch-2016.2.7). DisclosureAll authors have declared no conflicts of interest.

Long-Term Outcomes of Parathyroidectomy in Hyperparathyroidism-Jaw Tumor Syndrome: Analysis of Five Families with CDC73 Mutations.

Hyperparathyroidism-jaw tumor syndrome (HPT-JT) is a rare disease caused by CDC73 germline mutations, with familial primary hyperparathyroidism (pHPT), ossifying jaw tumors, genito-urinary neoplasms. The present study was aimed at determining the long-term postoperative outcome of parathyroidectomy in HPT-JT. A retrospective analysis of a single-center series of 20 patients from five unrelated HPT-JT families undergoing parathyroid surgery was performed. Pathology confirmed a single-gland involvement in 95% of cases at onset. Parathyroid carcinoma occurred in three patients undergoing en-bloc parathyroidectomy and thyroid lobectomy: parathyroid benign lesions in 17 patients undergoing subtotal parathyroidectomy for evident multiglandular involvement (n = 1) or selective parathyroidectomy for single-gland involvement (n = 16), during bilateral (n = 13) or targeted unilateral neck exploration (n = 7). At a median overall follow-up of 16years (range 2.5-42), patients with parathyroid carcinoma had a persistent/recurrent disease in 66.6%; patients with benign lesions had recurrent pHPT in 23.5% after a prolonged disease-free period; recurrent benign pHPT occurred slightly more often in cases of discordant preoperative localization (60% vs 9%; p = 0.06). pHPT in HPT-JT is generally characterized by a benign and single-gland involvement, with a relatively increased risk of malignancy (15%). Parathyroid carcinoma needs extensive surgery because of high risk of permanent/recurrent disease (66.6%). In benign involvement, targeted unilateral exploration with selective parathyroidectomy may be effective in cases of concordant single-gland localization at preoperative localization imaging techniques. Bilateral neck exploration with subtotal parathyroidectomy might be preferred in cases of negative or discordant preoperative localization, because of the increased risk of multiglandular involvement and long-term recurrences (23.5%).

Germline and Somatic Mutations of Genes Involved in Tumor Formation in Sporadic Renal Angiomyolipoma

Angiomyolipoma (AML) is one of the most frequent and, at the same time, AML molecular genetics is one of the least studied among benign tumors. We performed deep sequencing of 409 genes involved in oncogenesis in tumor samples and peripheral blood of patients with sporadic AML of the kidney. We recorded mutations in the TSC2 gene in 65% of samples, which is consistent with international results. As a result of our work, we uncovered mutations in the SETD2, PDGFRA, STK36, SYNE1, PIK3CD, NF1, TOP1, and ITGB3 genes in sporadic renal AML for the first time. In two samples, we were able to clarify the clinical and morphological diagnosis by finding mutations in the genes in tumors lacking TSC2 gene lesions. Mutations in MET and CDC73 are also causative for other types of renal tumors: papillary renal cell carcinoma and CDC73-related disorders, respectively. The latter disease is accompanied by kidney cysts and hamartomas. The obtained results demonstrate a promising potential of mutational profiling of sporadic renal angiomyolipoma (sAML). Genotyping of sAML is particularly important for clarification of the clinical diagnosis in ambiguous cases, as well as for a more in-depth understanding of AML molecular genetics and etiopathogenesis, and for the identification of new molecular targets for personalized AML therapies.