Monica Varun Tyagi’s research while affiliated with Stanford University and other places

Background: Genetic testing for germline pheochromocytoma and paraganglioma susceptibility genes is associated with improved patient management. However, data are currently sparse on the probability of a positive testing result based on an individual's clinical presentation. This study evaluates clinical characteristics for association with testing positive for known pheochromocytoma and paraganglioma susceptibility genes. Methods: This retrospective analysis examined 111 patients with a diagnosis of pheochromocytoma and paraganglioma who underwent genetic testing. Logistic regression and receiver operating characteristic analyses were performed to identify factors associated with a positive genetic testing result. Probabilities were then calculated for combinations of significant factors to determine the likelihood of a positive test result in each group. Results: Of 32 patients with a family history of pheochromocytoma and paraganglioma, 31 (97%) had a germline mutation detected. Of 79 patients without a family history, 24 (30%) had a pathogenic germline mutation detected. In multivariate analysis, a positive family history, aged ≤47 years, and tumor size ≤2.9 cm were independent factors associated with a positive genetic testing result. Patients meeting all 3 criteria had a 100% probability compared with 13% in those without any of the criteria. In addition to a positive family history, having either aged ≤47 years or tumor size ≤2.9 cm resulted in a 90% and 100% probability of a positive result, respectively. In the absence of a family history, the probability in patients who were aged ≤47 years and had a tumor size ≤2.9 cm was 60%. Conclusion: In addition to a family history of pheochromocytoma and paraganglioma, aged ≤47 years, and tumor size ≤2.9 cm are associated with a higher probability of testing positive for a pheochromocytoma and paraganglioma susceptibility gene mutation. Patients meeting all 3 criteria have a 100% probability of a positive genetic testing result.

Recent evidence has implicated APOBEC3B (Apolipoprotein B mRNA editing enzyme catalytic subunit 3B) as a source of mutations in breast, bladder, cervical, lung, head, and neck cancers. However, the role of APOBEC3B in adrenocortical carcinoma (ACC) and the mechanisms through which its expression is regulated in cancer are not fully understood. Here, we report that APOBEC3B is overexpressed in ACC and it regulates cell proliferation by inducing S phase arrest. We show high APOBEC3B expression is associated with a higher copy number gain/loss at chromosome 4 and 8 and TP53 mutation rate in ACC. GATA3 was identified as a positive regulator of APOBEC3B expression and directly binds the APOBEC3B promoter region. Both GATA3 and APOBEC3B expression levels were associated with patient survival. Our study provides novel insights into the function and regulation of APOBEC3B expression in addition to its known mutagenic ability.

The aim of this study is to determine the accuracy of adrenal vein sampling (AVS) with and without adrenocorticotropic hormone (ACTH) stimulation to distinguish between unilateral and bilateral primary hyperaldosteronism (PA). Retrospective analysis of a prospective database from a referral center between 1984 and 2009, 76 patients had simultaneous cannulation of bilateral adrenal veins and AVS with and without ACTH stimulation. All patients had adrenalectomies. The selectivity index (SI, cut-off value ≥2) was used for confirmation of successful cannulation of the adrenal vein. The lateralization index (LI, cut-off value >2 and >4) was used for distinguishing between unilateral and bilateral PA. The SI ratio was higher with ACTH stimulation compared to without for the right adrenal vein (p = 0.027). The LI >2 ratio was higher with ACTH stimulation compared to without (p = 0.007). For the LI >4 ratio, there was no difference between with and without ACTH stimulation (p = 0.239). However, for a LI >4, 7 patients (9.2%) were not lateralized with ACTH stimulation, but they did lateralize without ACTH stimulation. AVS with ACTH stimulation is associated with a higher SI ratio compared to AVS without ACTH stimulation. However, when using LI >4 for AVS, samples without ACTH stimulation should also be included to detect a subset of patients with unilateral disease that are not detected with ACTH stimulation.

Background Aberrant methylation is a known cause of cancer initiation and/or progression. There are scant data on the genome‐wide methylation pattern of nonfunctioning pancreatic neuroendocrine tumors (NFPanNETs) and sporadic and hereditary NFPanNETs. Methods Thirty‐three tissue samples were analyzed: they included samples from sporadic (n = 9), von Hippel‐Lindau (VHL)‐related (n = 10), and multiple endocrine neoplasia type 1 (MEN1)–related NFPanNETs (n = 10) as well as normal islet cells (n = 4) for comparison. Genome‐wide CpG methylation profiling was performed with the Infinium MethylationEPIC BeadChip assay and was analyzed with R‐based tools. Results In unsupervised hierarchical clustering, sporadic and MEN1‐related NFPanNETs clustered together, and the VHL group was in a separate cluster. MEN1‐related NFPanNETs had a higher rate of hypermethylated CpG sites in comparison with sporadic and VHL‐related tumor groups. Differentially methylated region analysis confirmed the higher rate of hypermethylation in MEN1‐related tumors. Moreover, in an integrated analysis of gene expression data for the same tumor samples, downregulated gene expression was found in most genes that were hypermethylated. In a CpG island methylator phenotype analysis, 3 genes were identified and confirmed to have downregulated gene expression: secreted frizzle‐related protein 5 (SFRP5) in sporadic NFPanNETs and cell division cycle–associated 7‐like (CDCA7L) and RNA binding motif 47 (RBM47) in MEN1‐related NFPanNETs. Conclusions MEN1 NFPanNETs have a higher rate of geno me‐wide hypermethylation than other NFPanNET subtypes. The similarity between the pathways enriched in a methylation analysis of known genes involved in NFPanNET tumorigenesis suggests a key role for aberrant methylation in the pathogenesis of NFPanNETs.