Search

Context: Parathyroid cancer has been linked to germline mutations of the CDC73 gene. However, carriers harboring cancer-associated germline CDC73 mutations may develop only parathyroid adenoma or no parathyroid disease. This incomplete penetrance indicates that additional genomic events are required for parathyroid tumorigenesis., Objective: (1) Determine the status of the second CDC73 allele in parathyroid tumors harboring germline CDC73 mutations, and (2) compare the genomic landscapes between parathyroid carcinomas and adenomas., Design: Whole-exome and RNA sequencing of 12 parathyroid tumors harboring germline CDC73 mutations (6 adenomas and 6 carcinomas) and their matched normal tissues., Results: All 12 parathyroid tumors had gained one somatic event predicted to cause a complete inactivation of the second CDC73 allele. Several distinctive genomic features were identified in parathyroid carcinomas compared to adenomas, including more single nucleotide variants bearing the C>G transversion and APOBEC deamination signatures, frequent mutations of the genes involved in the PI-3K/mTOR signaling, a greater number of copy number variations, and substantially more genes with altered expression. Parathyroid carcinomas also share some genomic features with adenomas. For instance, both have recurrent somatic mutations and copy number loss that impact the genes involved in T-cell receptor signaling and tumor antigen presentation, suggesting a shared strategy to evade immune surveillance., Conclusions: Biallelic inactivation of CDC73 is essential for parathyroid tumorigenesis in carriers harboring germline mutations of this gene. Despite sharing some genomic features with adenomas, parathyroid carcinomas have more distinctive alterations in the genome, some of which may be critical for cancer formation., (Published by Oxford University Press on behalf of the Endocrine Society 2024.)

A 51-year-old woman with a history of primary hyperparathyroidism (PHPT) with prior parathyroidectomy, osteoporosis, and learning disability was referred for hypercalcemia discovered after a fall. Family history was negative for PHPT, pituitary, enteropancreatic neuroendocrine, or jaw tumors. Dysmorphic facies, multiple cutaneous melanocytic nevi, café au lait macules, long fingers, and scoliosis were observed. Laboratory evaluation showed an elevated parathyroid hormone (PTH) level, hypercalcemia, and hypophosphatemia, all consistent with PHPT. Preoperative imaging revealed a right inferior candidate parathyroid lesion. The patient underwent right inferior parathyroidectomy with normalization of PTH, calcium, and phosphorus. Genetic testing showed a likely pathogenic de novo heterozygous germline missense variant p.R764W in the ZFX gene that encodes a zinc-finger transcription factor previously shown to harbor somatic missense variants in a subset of sporadic parathyroid tumors. Germline variants in ZFX have been reported in patients with an X-linked intellectual disability syndrome with an increased risk for congenital anomalies and PHPT. Further research may determine if genetic testing for ZFX could be of potential benefit for patients with PHPT and developmental anomalies, even in the absence of a family history of parathyroid disease., (Published by Oxford University Press on behalf of the Endocrine Society 2024.)

How ancestry-associated genetic variance affects disparities in the risk of polygenic diseases and influences the identification of disease-associated genes warrants a deeper understanding. We hypothesized that the discovery of genes associated with polygenic diseases may be limited by the overreliance on single-nucleotide polymorphism (SNP)-based genomic investigation, as most significant variants identified in genome-wide SNP association studies map to introns and intergenic regions of the genome. To overcome such potential limitations, we developed a gene-constrained, function-based analytical method centered on high-risk variants (hrV) that encode frameshifts, stopgains or splice site disruption. We analyzed the total number of hrV per gene in populations of different ancestry, representing a total of 185 934 subjects. Using this analysis, we developed a quantitative index of hrV (hrVI) across 20 428 genes within each population. We then applied hrVI analysis to the discovery of genes associated with type 2 diabetes mellitus (T2DM), a polygenic disease with ancestry-related disparity. HrVI profiling and gene-to-gene comparisons of ancestry-specific hrV between the case (20 781 subjects) and control (24 440 subjects) populations in the T2DM national repository identified 57 genes associated with T2DM, 40 of which were discoverable only by ancestry-specific analysis. These results illustrate how a function-based, ancestry-specific analysis of genetic variations can accelerate the identification of genes associated with polygenic diseases. Besides T2DM, such analysis may facilitate our understanding of the genetic basis for other polygenic diseases that are also greatly influenced by environmental and behavioral factors, such as obesity, hypertension and Alzheimer's disease., (Published by Oxford University Press 2022.)

Disease-associated variants identified from genome-wide association studies (GWASs) frequently map to non-coding areas of the genome such as introns and intergenic regions. An exclusive reliance on gene-agnostic methods of genomic investigation could limit the identification of relevant genes associated with polygenic diseases such as Alzheimer disease (AD). To overcome such potential restriction, we developed a gene-constrained analytical method that considers only moderate- and high-risk variants that affect gene coding sequences. We report here the application of this approach to publicly available datasets containing 181,388 individuals without and with AD and the resulting identification of 660 genes potentially linked to the higher AD prevalence among Africans/African Americans. By integration with transcriptome analysis of 23 brain regions from 2,728 AD case-control samples, we concentrated on nine genes that potentially enhance the risk of AD: AACS, GNB5, GNS, HIPK3, MED13, SHC2, SLC22A5, VPS35, and ZNF398. GNB5, the fifth member of the heterotrimeric G protein beta family encoding Gβ5, is primarily expressed in neurons and is essential for normal neuronal development in mouse brain. Homozygous or compound heterozygous loss of function of GNB5 in humans has previously been associated with a syndrome of developmental delay, cognitive impairment, and cardiac arrhythmia. In validation experiments, we confirmed that Gnb5 heterozygosity enhanced the formation of both amyloid plaques and neurofibrillary tangles in the brains of AD model mice. These results suggest that gene-constrained analysis can complement the power of GWASs in the identification of AD-associated genes and may be more broadly applicable to other polygenic diseases., Competing Interests: Declaration of interests The authors declare no competing interests., (Published by Elsevier Inc.)

Context: The identification of parathyroid tumor(s) in patients with persistent/recurrent primary hyperparathyroidism (PHPT) is critical for a successful reoperative surgery. If noninvasive studies (ultrasound, computed tomography, magnetic resonance imaging, sestamibi) fail to conclusively localize the tumor, invasive procedures (arteriography and selective venous sampling) are performed., Objective: To describe our experience with invasive studies for parathyroid tumor localization and provide follow-up data on selective arterial hypocalcemic stimulation with central venous sampling, a technique developed at our center., Methods: We identified patients who underwent preoperative invasive testing for localization of parathyroid tumor from 1991 to 2020. The result of each invasive localization study [arteriogram, hypocalcemic stimulation and selective venous sampling (SVS)] was categorized as true-positive, false-positive, and false-negative based on histology and biochemical outcome., Results: Ninety-four patients with 96 tumor occurrences underwent invasive testing for parathyroid tumor localization. Arteriogram, hypocalcemic stimulation, and SVS accurately localized the tumor in 47 of 94 (50%), 56 of 93 (60%), and 51 of 62 (82%) tumors, respectively. Hypocalcemic stimulation was more likely to correctly localize the tumor when arteriogram showed a blush [37 of 50 (74%) vs 19 of 43 (44%), P = .01]. When both arteriogram and hypocalcemic stimulation yielded concordant positive findings, SVS did not change management in the 18 cases in which all 3 were performed. Twelve patients remained with persistent PHPT; all had recurrent disease with multiple affected glands., Conclusion: Hypocalcemic stimulation is a useful adjunct in patients with PHPT who require invasive localization and can obviate the need for SVS. Clinical Trial number : NCT04969926., (Published by Oxford University Press on behalf of the Endocrine Society 2024.)