Characterization of a New CDC73 Missense Mutation that Impairs Parafibromin Expression and Nucleolar Localization

Mutations of the Cell Division Cycle 73 (CDC73) tumor suppressor gene (previously known as HRPT2), encoding for parafibromin, are associated with the Hyperparathyroidism-Jaw Tumor (HPT-JT) syndrome, an autosomal dominant disease whose clinical manifestations are mainly parathyroid tumors and, less frequently, ossifying fibromas of the jaws, uterine and renal tumors. Most mutations of CDC73 are nonsense or frameshift, while missense mutations are rare and generally affect the N-terminal domain of parafibromin, a region that is still poorly characterized. The aim of this study was to characterize a novel somatic CDC73 missense mutation (Ile60Asn) identified in the mandibular tumor of a HPT-JT patient carrying a germline CDC73 inactivating mutation. Immunostaining of the tumor showed reduced nuclear parafibromin immunoreactivity. Western blotting and confocal microscopy of transfected cells demonstrated that the Ile60Asn mutant parafibromin was less expressed than the wild-type protein and exhibited impaired nucleolar localization. Treatment of transfected cells with translation and proteasome inhibitors demonstrated a decreased stability of the Ile60An mutant, partially due to an increase in proteasomal degradation. Overexpression of the Ile60Asn mutant led to increased cell proliferation and to accumulation in the G2/M phase of cell cycle. Moreover, mutant parafibromin lost the ability to down-regulate c-myc expression. In conclusion, our study shows that a missense mutation in the N-terminus of parafibromin, identified in an ossifying fibroma from a HPT-JT patient, stimulated cell proliferation and impaired parafibromin expression and nucleolar localization, suggesting a relevant role of the N-terminal domain for parafibromin function.     

Identification and Functional Characterization of Three NoLS (Nucleolar Localisation Signals) Mutations of the CDC73 Gene

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.     

HRPT2- (CDC73) Related Hereditary Hyperparathyroidism: A Case Series From Western India

Objective: To describe a case series of HRPT2- (CDC73) related hereditary primary hyperparathyroidism (PHPT) from western India.Methods: We present a case series of 4 families (7 patients) with PHPT caused by CDC73 gene mutations.Results: The mean age of presentation of the 4 index cases was 27.25 ± 9.8 years. Two family members were identified through biochemical screening (Cases 1b and 2b), while 1 mutation-positive family member did not manifest any features of PHPT or hyperparathyroidism jaw tumor syndrome (HPT-JT) syndrome (Case 2c). Biochemistry showed increased serum calcium (mean: 13.21 ± 1.24 mg/dL), low serum phosphorus (mean: 1.78 ± 0.44 mg/dL), and high parathyroid hormone (PTH, mean: 936 ± 586.9 pg/mL).All patients had a uniglandular presentation and underwent single adenoma excision initially except Cases 2a and 2b, who underwent subtotal parathyroidectomy at baseline. Two cases experienced PHPT recurrence (Cases 3 and 4), while 1 remained uncured due to parathyroid carcinoma (Case 1a). Other associated syndromic features like ossifying jaw fibromas were present in 2 patients, renal cysts in 3 patients, and uterine involvement in 2 patients. Two families had novel germline CDC73 mutations (Families 1 and 3), while the other 2 had reported mutations. Family 2 had familial isolated PHPT without any other features of HPT-JT syndrome.Conclusion: Our findings reaffirm the need for genetic analysis of patients with PHPT, especially those with younger age of disease onset; recurrent disease; and associated features like polycystic kidneys, endometrial involvement, ossifying jaw tumors, or parathyroid carcinoma.Abbreviations: FIHP = familial isolated hyperparathyroidism HPT-JT = hyperparathyroidism jaw tumor syndrome PHPT = primary hyperparathyroidism PTH = parathyroid hormone ⁹⁹Tc = ⁹⁹Technetium     

Primary Hyperparathyroidism and Jaw Tumor Syndrome: A Novel Mutation of the HRPT2 Gene

ObjectiveTo discuss a case of hyperparathyroidismjaw tumor syndrome (HPT-JT) and its clinical course, as well as describe a new mutation within HRPT2, the gene associated with HPT-JT.MethodsWe describe the clinical course, laboratory data, and diagnostic imaging of a patient with HPT-JT, including the mutation analysis of the HRPT2 gene. A review of the related literature is also presented.ResultsA 22-year-old man presented with progressive bone pain and weakness, and investigation revealed a serum calcium level of 17.6 mg/dL, a phosphorus concentration of 1.8 mg/dL, and an intact parathyroid hormone value of 2,808 pg/mL. X-ray examinations showed a fracture of the left hip and compression fractures of the lumbar spine. Computed tomography disclosed a mass in his mandible, clinically suggesting HPT-JT. Genetic analysis of the HRPT2 gene demonstrated a frameshift mutation resulting in a premature stop codon. The patient underwent parathyroidectomy, and 1 year later his fractures had healed and dual-energy x-ray absorptiometry showed substantial improvement in bone mineral density.ConclusionPrevious reports have cited mutations of the gene HRPT2 leading to HPT-JT and its associated phenotypes. We report one such mutation, not reported previously, in a patient with HPT-JT. This case adds to the growing evidence that different mutations in the HRPT2 gene can lead to HPT-JT, although it remains unclear whether specific mutations are more strongly associated with a particular phenotype. (Endocr Pract. 2008;14: 743-747)     

Retraction Note: Neuropathological and neuroprotective features of vitamin B12 on the dorsal spinal ganglion of rats after the experimental crush of sciatic nerve: an experimental study

The 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. We 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. Two 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. Mutations inCDC73 were rare in sporadic OF of the jaws, but may affect the pathogenesis of a small subset of tumors of this type.     

Parathyroid Carcinoma in Multiple Endocrine Neoplasia Type 1 with a Classic Germline Mutation

ObjectiveTo report the case of a patient with multiple endocrine neoplasia type 1 (MEN 1) syndrome with concomitant parathyroid carcinoma and a classic MEN1 germline mutation.MethodsWe present the clinical findings, laboratory results, imaging studies, and surgical histopathologic features in a woman with MEN 1 syndrome and concomitant parathyroid carcinoma. We also review the literature regarding patients with similar clinical entities and the use of adjuvant radiotherapy for parathyroid carcinoma.ResultsA 53-year-old woman presented with nausea and severe primary hyperparathyroidism. Computed tomography revealed parathyroid masses, shown later to be bilateral parathyroid carcinomas and adenomas. Magnetic resonance imaging demonstrated a pituitary macroadenoma, and gastrinomas were confirmed by computed tomography and a secretin stimulation test. She was successfully treated with total thyroidectomy, subtotal parathyroidectomy, and adjuvant radiotherapy. Genetic analysis revealed a classic MEN1 germline mutation.ConclusionThis report describes a patient with parathyroid carcinoma occurring in conjunction with MEN 1, further characterizing this rare condition. In contrast to previously described patients, our patient is the first with a classic MEN1 germline mutation, confirming that parathyroid cancer can occur in association with classic MEN 1 genetics. (Endocr Pract. 2009;15:567-572)     

A Novel Gata3 Nonsense Mutation In A Newly Diagnosed Adult Patient Of Hypoparathyroidism,Deafness, And Renal Dysplasia (Hdr) Syndrome

ObjectiveHypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome is an autosomal dominant disorder caused by a GATA3 gene mutation. Here we report a novel mutation of GATA3 in a patient diagnosed with HDR syndrome at the age of 58 with extensive intracranial calcification.MethodsA 58-year-old Japanese man showed severe hypocalcemia and marked calcification in the basal ganglia, cerebellum, deep white matter, and gray-white junction on computed tomography (CT). The serum intact parathyroid hormone level was relatively low against low serum calcium concentration. The patient had been diagnosed with bilateral sensorineural deafness in childhood and had a family history of hearing disorders. Imaging studies revealed no renal anomalies. The patient was diagnosed with HDR syndrome, and genetic testing was performed.ResultsGenetic analysis of GATA3 showed a novel nonsense mutation at codon 198 (S198X) in exon 3. The S198X mutation leads to a loss of two zinc finger deoxyribonucleic acid (DNA) binding domains and is considered to be responsible for HDR syndrome.ConclusionWe identified a novel nonsense mutation of GATA3 in an adult patient with HDR syndrome who showed extensive intracranial calcification. (Endocr Pract. 2013;19:e17-e20)     

Novel HRPT2/CDC73 Gene Mutations and Loss of Expression of Parafibromin in Chinese Patients with Clinically Sporadic Parathyroid Carcinomas

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.     

An Unusual Case of Primary Hyperparath Yroidism with Profoundly Elevated Parath Yroid Hormone Levels

ObjectiveTo report the case of a man who presented with profoundly elevated parathyroid hormone levels in the setting of hypercalcemia, a palpable neck mass, renal disease, and metabolic bone disease.MethodsWe describe the clinical, imaging, and laboratory findings of the patient, including results from genetic testing of the CDC73 gene (HRPT2), and review the relevant literature.ResultsA 28-year-old man with a history of childhood abdominal neuroblastoma treated with chemotherapy and field radiation therapy presented with a 2-week history of persistent left scapular pain and swelling. He had a freely mobile, 1-cm, homogeneous, nontender, firm nodule in the right anterior neck. Parathyroid hormone concentration at hospital admission was 1127 pg/mL. Single-photon emission computed tomography after intravenous administration of technetium Tc 99m–labeled sestamibi revealed an intense focus of abnormal radiotracer uptake on early and delayed images in the right anterior inferior neck. Computed tomography imaging of the chest and neck revealed a 1.9-cm, smooth, calcified nodule posterior to the right lobe of the thyroid gland and diffusely osteopenic bones with trabecular resorption and numerous scattered lucent regions consistent with brown tumors. On bilateral neck exploration, a right inferior parathyroid mass and the left superior parathyroid gland were excised. The remaining 2 parathyroid glands were identified intraoperatively and appeared normal. Genetic testing of the CDC73 gene did not detect germline mutations.ConclusionsThis case highlights the overlap between the clinical findings seen in primary hyperparathyroidism and parathyroid carcinoma. Enhanced understanding of the genetic and molecular bases of primary hyperparathyroidism and parathyroid carcinoma should aid in the diagnosis of these diseases and the care of affected patients. (Endocr Pract. 2008;14:892-897)     

Diagnostic Fine-Needle Aspiration Biopsy of an Intrathyroidal Parathyroid Gland and Subsequent Eucalcemia in a Patient with Primary Hyperparathyroidism

ObjectiveTo present the clinical course of a patient with persistent primary hyperparathyroidism (PHPT) whose intrathyroidal parathyroid gland was diagnosed by ultrasound-guided fine-needle aspiration biopsy (FNAB).MethodsWe describe the clinical course and laboratory, radiographic, and microscopic findings of a patient with persistent PHPT due to an intrathyroidal cystic parathyroid gland and review the relevant literature.ResultsA 74-year-old man with PHPT (presenting serum calcium concentration, 16.2 mg/dL; intact parathyroid hormone [PTH] concentration, 341 pg/mL) had surgical excision of the right superior, right inferior, and left inferior parathyroid glands, but the left superior parathyroid gland remained unidentified. Microscopic examination revealed parathyroid hyperplasia. Technetium Tc 99m sestamibi single-photon emission computed tomography imaging showed uptake in 2 foci, 1 on each side of midline in the neck. Reoperation with attention to the left neck failed to locate another parathyroid gland. Neck ultrasonography demonstrated a complex nodule within the right lower lobe of the thyroid. Results from FNAB of the solid component were consistent with parathyroid cells, and cystic fluid PTH concentration was greater than 1800 pg/mL. Nine months later, neck ultrasonography showed a hypoechoic area located posterior to the inferior pole of the right thyroid. The patient remained eucalcemic 16 months postprocedure.ConclusionAutoinfarction of the parathyroid gland and aspiration of cystic fluid may explain resolution of hypercalcemia. Although PHPT due to functioning parathyroid cysts is rare, and PHPT due to cystic parathyroid hyperplasia has been described, this is the first case report of a patient with persistent PHPT due to a functional parathyroid cyst whose diagnosis by FNAB was followed by eucalcemia. (Endocr Pract. 2008;14:80-86)     

Germline GCM2 Mutation Screening in Chinese Primary Hyperparathyroidism Patients

Objective: Glial cell missing 2 (GCM2), the critical regulator in the development of parathyroid glands, has been associated with the pathogenesis of primary hyperparathyroidism (PHPT). Relevant data in Chinese and other Asian populations are still lacking. This study aimed to screen the germline mutations of GCM2 in Chinese PHPT patients.Methods: A total of 232 patients diagnosed with PHPT at the Peking Union Medical College Hospital from July, 2016, to February, 2019, were screened using targeted next-generation sequencing to identify rare variants of 8 candidate genes associated with PHPT, including GCM2. Luciferase assays were performed to determine the functional impact of the GCM2 variants.Results: Four male patients were found to carry 3 rare missense variants of the GCM2 gene, including c.1162A>G (p.K388E), c.1144G>A (p.V382M), and c.1247A>G (p.Y416C). Two variants (p.K388E and p.V382M) located within a highly conserved region were associated with GCM2 transactivation function. The 2 cases carrying the p.K388E mutation had a pathology of carcinoma, and the case with the p.V382M mutation had atypical adenoma.Conclusion: This study determined an overall GCM2 gain-of-function mutation frequency of 1.3% in a relatively large-sample-sized Chinese PHPT cohort and supported a higher malignant tendency in cases carrying activating GCM2 mutations. Hence, preoperative screening for these GCM2 mutations might be beneficial to treatment decisions, and longer follow-up for such patients is recommended.     

The EIF4EBP3 translational repressor is a marker of CDC73 tumor suppressor haploinsufficiency in a parathyroid cancer syndrome

Germline mutation of the tumor suppressor gene CDC73 confers susceptibility to the hyperparathyroidism-jaw tumor syndrome associated with a high risk of parathyroid malignancy. Inactivating CDC73 mutations have also been implicated in sporadic parathyroid cancer, but are rare in sporadic benign parathyroid tumors. The molecular pathways that distinguish malignant from benign parathyroid transformation remain elusive. We previously showed that a hypomorphic allele of hyrax (hyx), the Drosophila homolog of CDC73, rescues the loss-of-ventral-eye phenotype of lobe, encoding the fly homolog of Akt1s1/ PRAS40. We report now an interaction between hyx and Tor, a central regulator of cell growth and autophagy, and show that eukaryotic translation initiation factor 4E-binding protein (EIF4EBP), a translational repressor and effector of mammalian target of rapamycin (mTOR), is a conserved target of hyx/CDC73. Flies heterozygous for Tor and hyx, but not Mnn1, the homolog of the multiple endocrine neoplasia type 1 (MEN1) tumor suppressor associated with benign parathyroid tumors, are starvation resistant with reduced basal levels of Thor/4E-BP. Human peripheral blood cell levels of EIF4EBP3 were reduced in patients with CDC73, but not MEN1, heterozygosity. Chromatin immunoprecipitation demonstrated occupancy of EIF4EBP3 by endogenous parafibromin. These results show that EIF4EBP3 is a peripheral marker of CDC73 function distinct from MEN1-regulated pathways, and suggest a model whereby starvation resistance and/or translational de-repression contributes to parathyroid malignant transformation.     

Coexistence of tumor-induced osteomalacia and primary hyperparathyroidism

ObjectiveTo present an unusual case of coexisting tumor-induced osteomalacia (TIO) and primary hyperparathyroidism (PHPT).MethodsWe report the clinical features, imaging studies, and the results of laboratory investigations before and after surgical resection of both a soft-tissue tumor and a parathyroid adenoma.ResultsA 44-year-old woman was referred to the endocrinology department with a diagnosis of PHPT accompanied by unusually severe hypophosphatemia, despite having received treatment with cinacalcet. Debilitating muscle weakness and bone pain, severe phosphaturia and hypophosphatemia, inappropriately normal calcitriol, and elevated fibroblast growth factor-23 and intact parathyroid hormone levels raised the suspicion of coexisting TIO and PHPT. Imaging studies were negative, but histologic characteristics of a palpable subcutaneous mass from the patient’s thigh revealed a phosphaturic mesenchymal tumor. Complete remission after surgical removal of both the soft-tissue tumor and the parathyroid adenoma confirmed the diagnosis.ConclusionThe coexistence of TIO and PHPT has not been described before and can cause life-threatening hypophosphatemia. Diagnosis and localization of the tumor is of paramount importance since surgery is the treatment of choice for both TIO and PHPT. (Endocr Pract. 2011;17:e144-e148)     

Genome-Wide and Locus Specific Alterations in CDC73/HRPT2-Mutated Parathyroid Tumors

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.     

Evolution of Surgical Treatment of Primary Hyperparathyroidism in Patients With Multiple Endocrine Neoplasia Type 2A

ObjectiveTo determine the best surgical strategy for patients with multiple endocrine neoplasia type 2A (MEN 2A) who have primary hyperparathyroidism (PHPT).MethodsWe performed a systematic literature review and conducted a retrospective cohort study that included patients with PHPT identified from the MEN 2A database at the University Medical Center of Utrecht, Utrecht, the Netherlands, between 1979 and 2009.ResultsThe review describes the course of worldwide parathyroid surgical management in MEN 2A PHPT over the past 75 years, which has evolved from aggressive parathyroid resections to minimally invasive parathyroidectomy (MIP). The study cohort included 20 patients. Primary surgery for parathyroid disease in patients with MEN 2A (n = 16) included MIP (n = 6), conventional neck exploration with resection of enlarged parathyroid gland(s) (n = 4), and resection of 1 or more enlarged gland(s) during total thyroidectomy (n = 6). Thirteen patients were initially cured after the primary operation. Five patients experi enced persistent or recurrent PHPT. After MIP, 1 patient had persistent PHPT, but no patient developed recurrent PHPT during 5 years of follow-up. Five patients had hypoparathyroidism after subtotal or total parathyroidectomy with autotransplantation, but only 1 patient had transient hypoparathyroidism after MIP. One patient had transient recurrent laryngeal nerve injury after MIP.ConclusionsSurgery for PHPT in patients with MEN 2A has evolved from aggressive conventional exploration of all 4 glands to focused MIP, which appears to be a feasible approach. MIP has low rates of persistent and recurrent PHPT, and the complications are minimal. (Endocr Pract. 2011;17:7-15)     

A Patient With Hypophosphatemia,a Femoral Fracture,and Recurrent Kidney Stones: Report of a Novel Mutation in SLC34A3

ObjectiveTo determine if there was a genetic contribution to our patient’s unusual clinical presentation of nephrolithiasis and nonhealing stress fracture.MethodsWe describe a 31-year-old man who had rickets as a child and developed a femur insufficiency fracture and recurrent nephrolithiasis as an adult after moving to the United States from India. The patient’s clinical course and results from radiographic and biochemical analyses are described. Analysis of the SLC34A3 gene was performed using genomic DNA samples from the patient and his family members.ResultsBefore referral to the Yale Bone Center, the patient was treated with calcitriol, ergocalciferol, and phosphate. Changing therapy to phosphate alone led to clinical improvement. Genetic analysis revealed that the patient is a compound heterozygote for mutations in the SLC34A3 gene. On 1 allele, he has a previously described missense mutation in exon 7: c.575C > T (p.Ser192Leu). The other allele carries a novel nonsense mutation in exon 3: c.145C > T (p.Gln49X). One unaffected sibling is a carrier of the missense mutation and 1 sister with a history of flank pain is a carrier of the novel mutation.ConclusionsHereditary hypophosphatemic rickets with hypercalciuria is a rare metabolic disorder associated with mutations in SLC34A3, the gene that encodes the renal sodium phosphate cotransporter NaPi-IIc. Although hypercalciuria is a distinguishing feature of the disease, nephrolithiasis is rarely described. The patient’s atypical clinical presentation illustrates that both environmental and genetic factors potentially affect phenotypic expression of SLC34A3 mutations. (Endocr Pract. 2008;14:869-874)     

Primary Hyperparathyroidism During Pregnancy: A Case Series of 8 Patients

Objective: Due to a lack of typical clinical manifestations and physiologic changes in calcium metabolism during pregnancy, primary hyperparathyroidism (PHPT) during pregnancy is commonly underdiagnosed, and treatment during this unique period presents a clinical challenge. Hence, the aim of the present study was to summarize the cases of 8 pregnant patients with PHPT who were treated at our center to provide better clinical insight into this condition.Methods: Our study comprised a retrospective analysis of 8 pregnant PHPT patients and a control group of 22 age-matched, nonpregnant PHPT patients during the same period. Clinical manifestations, biochemical indices, pathologic types, therapeutic strategies, and pregnancy outcomes were compiled, and 25 patients were screened for germline mutations in the MEN1, CDC73, and CaSR genes.Results: The most-common symptoms in the pregnancy group involved the gastrointestinal tract (GIT) in 7/8 cases (87.5%), followed by urinary system involvement (50%) and joint pain (50%). In contrast, GIT symptoms in the control group were significantly less common (31.82%; P = .012). There was a trend of more-severe elevation of serum parathyroid hormone levels in the control group compared to that in the pregnancy group (P = .053). No differences were found in blood-ionized calcium, phosphate, or alkaline phosphatase levels between the two groups. In the pregnancy group, the serum albumin-corrected calcium level was reduced from 3.42 ± 0.66 mmol/L to 2.89 ± 0.46 mmol/L (P = .025) after hydration and medical treatment. Six patients, three of whom were in the second trimester of pregnancy, underwent parathyroidectomy, and 3 patients were after childbirth or had induced labor. Postoperative serum calcium levels were reduced to within the normal range. Fetal/neonatal complications were observed in 4 of 5 patients who had not received surgical treatment during pregnancy. In addition, 2 of 5 pregnant PHPT patients were found to carry MEN1 mutations, whereas no mutations were detected in any of the 20 nonpregnant patients.Conclusion: In this case series of PHPT during pregnancy, the most-common complaint of GIT symptoms may be easily confused with pregnancy reactions, which might contribute to the under- or misdiagnosis of this clinical entity. Patients who did not receive surgical treatment during pregnancy had high incidences of fetal/neonatal complications and worse pregnancy outcomes.Abbreviations: CaSR = calcium-sensing receptor; CDC73 = cell division cycle 73; GIT = gastrointestinal tract; MEN = multiple endocrine neoplasia; PHPT = primary hyperparathyroidism; PTH = parathyroid hormone; SCa = serum calcium     

Synchronous Parathyroid Carcinoma,Parathyroid Adenoma,and Papillary Thyroid Carcinoma in a Patient with Severe and Long-Standing Hyperparathyroidism

ObjectiveTo describe a patient presenting with the rare constellation of synchronous parathyroid carcinoma, parathyroid adenoma, and papillary thyroid carcinoma.MethodsWe summarize the clinical presentation, diagnostic work-up, surgical management, and pathologic features of our patient and review the pertinent literature.ResultsThe patient was a 59-year-old man who presented with severe clinical manifestations of long-standing primary hyperparathyroidism, a serum calcium concentration of 14.4 mg/dL, and a parathyroid hormone level of 2,023 pg/mL. He was found to have a 3.4-cm parathyroid carcinoma on the left side and a 3.2-cm papillary carcinoma in the right thyroid lobe. In addition, a 917-mg parathyroid adenoma was found on the right side.ConclusionSynchronous parathyroid and thyroid carcinomas are extremely rare. To our knowledge, our patient is the first documented case with a parathyroid adenoma in addition to synchronous parathyroid and thyroid carcinomas. The presence of concurrent parathyroid carcinoma and parathyroid adenoma can cause diagnostic confusion and should be considered in patients presenting with severe hyperparathyroidism. Any concomitant thyroid nodules must be investigated to rule out thyroid carcinoma. (Endocr Pract. 2009;15:463-468)     

Incidental Finding of Metastatic Papillary Thyroid Carcinoma in a Patient with Primary Hyperparathyroidism

ObjectiveTo report on the management of a patient with the rare concurrence of primary hyperparathyroidism and incidentally found metastatic papillary thyroid carcinoma in an adjacent lymph node.MethodsWe present a case report, including scintigraphic and histologic documentation, and a summary of the related literature.ResultsPrimary hyperparathyroidism with concomitant occurrence of nonmedullary thyroid carcinoma is rare, occurring in less than 4% of patients. We report a case of a 53-year-old woman with no prior history of endocrine disease with primary hyperparathyroidism and an incidental finding of a concurrent thyroid carcinoma. In this patient, technetium 99m scintigraphy revealed a parathyroid adenoma beneath the inferior pole of the left thyroid bed. Parathyroidectomy was performed successfully with no complications. The final pathology examination showed a large parathyroid adenoma with an incidental finding of a small adjacent lymph node containing metastatic papillary thyroid carcinoma. The patient subsequently underwent total thyroidectomy, and the pathology evaluation revealed papillary thyroid carcinoma, follicular variant.ConclusionTo our knowledge, this case of concomitant primary hyperparathyroidism and papillary thyroid cancer is unique in the way in which the diagnosis of metastatic papillary thyroid cancer was made. The presence of parathyroid adenoma should not exclude the diagnosis of thyroid carcinoma; therefore, careful thyroid evaluation should be considered for all patients with primary hyperparathyroidism. (Endocr Pract. 2007;13:380-383)     

Characteristics of Ectopic Parathyroid Glands in 145 Cases of Primary Hyperparathyroidism

ObjectiveTo determine the prevalence of primary hyperparathyroidism (PHPT) arising from ectopic parathyroid glands, to analyze the clinical, biochemical, and anatomic characteristics of such cases, and to compare these characteristics with those found in PHPT associated with orthotopic parathyroid glands.MethodsWe conducted a retrospective study of cases of PHPT evaluated and treated at a referral center. Differences between patients with orthotopic and ectopic parathyroid glands were analyzed statistically.ResultsDuring a recent 5-year period at our institution, 145 cases of PHPT were treated operatively by 3 experienced surgeons. An ectopic parathyroid location was detected in 13 cases (9%). Of the 13 ectopic glands, 4 (31%) were at the tracheoesophageal groove, 4 (31%) were intrathymic, 2 (15%) were intrathyroidal, and 1 each was located in the aortopulmonary window, the anterior (nonthymic) mediastinum, and the submaxillary region. Patients with PHPT attributable to ectopic adenomas had significantly higher serum calcium levels (12.6 ± 0.9 mg/ dL versus 11.4 ± 1.2 mg/dL; P = .05) and larger tumors (25 ± 6.1 mm versus 19 ± 7.6 mm; P = .05) than did patients with orthotopic parathyroid glands. Moreover, hyperparathyroidism-related bone disease was significantly more frequent in patients with abnormal ectopic parathyroid glands than in those with orthotopic parathyroid glands (23% versus 1.5%, respectively; P = .04).ConclusionIn 9% of all cases of PHPT in our study, the condition was associated with ectopically located parathyroid glands. Such cases are usually characterized by larger parathyroid glands, higher serum calcium levels, and a higher frequency of severe bone disease. (Endocr Pract. 2010;16:977-981)