Disclosure of cardiac variants of uncertain significance results in an exome cohort

This study examined the impact of disclosing subclassifications of genetic variants of uncertain significance (VUS) on behavioral intentions. We studied return of VUS results to 79 individuals with a cardiomyopathy‐associated VUS, subclassified into VUS‐high or VUS‐low. Primary outcomes were perceived risk (absolute and comparative), perceived severity, perceived value of information, self‐efficacy, decision regret, and behavioral intentions to share results and change behaviors. There was no significant difference between the 2 subclasses in overall behavioral intentions (t = 0.023, P = .982) and each of the individual items on the behavioral intentions scale; absolute (t = ?1.138, P = .259) or comparative (t = ?0.463, P = .645) risk perceptions; perceived value of information (t = 0.582, P = .563) and self‐efficacy (t = ?0.733, P = .466). Decision regret was significantly different (t = 2.148, P = .035), with VUS‐low (mean = 17.24, SD = 16.08) reporting greater regret. Combining the subclasses, perceived value of information was the strongest predictor of behavioral intentions (β = 0.524, P < .001). Participants generally understood the meaning of a genetic VUS result classification and reported satisfaction with result disclosure. No differences in behavioral intentions were found, but differences in decision regret suggest participants distinguish subclasses of VUS results. The perceived value of VUS may motivate recipients to pursue health‐related behaviors.     

A guide for functional analysis of BRCA1 variants of uncertain significance

Germline mutations in the tumor suppressor gene BRCA1 confer an estimated lifetime risk of 56–80% for breast cancer and 15–60% for ovarian cancer. Since the mid 1990s when BRCA1 was identified, genetic testing has revealed over 1,500 unique germline variants. However, for a significant number of these variants, the effect on protein function is unknown making it difficult to infer the consequences on risks of breast and ovarian cancers. Thus, many individuals undergoing genetic testing for BRCA1 mutations receive test results reporting a variant of uncertain clinical significance (VUS), leading to issues in risk assessment, counseling, and preventive care. Here, we describe functional assays for BRCA1 to directly or indirectly assess the impact of a variant on protein conformation or function and how these results can be used to complement genetic data to classify a VUS as to its clinical significance. Importantly, these methods may provide a framework for genome‐wide pathogenicity assignment. Hum Mutat 33:1526–1537, 2012. © 2012 Wiley Periodicals, Inc.     

Functional Assays for Analysis of Variants of Uncertain Significance in BRCA2

Missense variants in the BRCA2 gene are routinely detected during clinical screening for pathogenic mutations in patients with a family history of breast and ovarian cancer. These subtle changes frequently remain of unknown clinical significance because of the lack of genetic information that may help establish a direct correlation with cancer predisposition. Therefore, alternative ways of predicting the pathogenicity of these variants are urgently needed. Since BRCA2 is a protein involved in important cellular mechanisms such as DNA repair, replication, and cell cycle control, functional assays have been developed that exploit these cellular activities to explore the impact of the variants on protein function. In this review, we summarize assays developed and currently utilized for studying missense variants in BRCA2. We specifically depict details of each assay, including variants of uncertain significance analyzed, and describe a validation set of (genetically) proven pathogenic and neutral missense variants to serve as a golden standard for the validation of each assay. Guidelines are proposed to enable implementation of laboratory‐based methods to assess the impact of the variant on cancer risk.     

Reporting practices for variants of uncertain significance from next generation sequencing technologies

The nature of next generation sequencing technologies (NGS) results in the generation of large amounts of data and the identification of numerous variants, for some of which the clinical significance may be difficult to ascertain based on our current knowledge. These Variants of Uncertain Significance (VUS) may be identified in genes in which the function is known or unknown and which may or may not be related to the original rationale for sequencing the patient. Little is known about whether laboratories report VUS to clinicians and current guidelines issued by some of the most notable professional bodies do not provide specific recommendations on this point. To address this, 26 interviews were conducted with 27 laboratory personnel, representing 24 laboratories in Europe (12), Canada (5) and Australasia (7) in order to explore their reporting practices. Participants highlighted that the classification of variants is a real challenge despite the presence of classification guidelines. We identified variation in the reporting practices of VUS across the laboratories within the study. While some laboratories limit their reporting to variants that are pathogenic and thought to be causative of the phenotype, more commonly laboratories report VUS when they are identified in genes related to the clinical question. Some laboratories will also report VUS in candidate genes. VUS that are secondary findings are generally not reported. While it is unclear whether uniformity in reporting is desirable, exploring the perspectives of laboratory personnel undertaking these analyses are critical to ensure the feasibility of any future reporting recommendations.     

Likelihood ratios to assess genetic evidence for clinical significance of uncertain variants: hereditary hemorrhagic telangiectasia as a model

Clinical laboratories performing gene sequencing discover previously unreported and/or uncharacterized variants. Often these are missense or intronic mutations in which the contribution to disease cannot be predicted, and consequently these mutations are reported as variants of uncertain significance. Follow-up to assess family concordance is recommended by the American College of Medical Genetics to provide genetic evidence for clinical significance. Although family concordance studies show whether a variant segregates with disease in the family, the strength of evidence varies depending on the number and degree of relatedness of family members available for testing. We investigated a statistical model which accounts for the pedigree, inheritance patterns, and penetrance to determine the likelihood of a variant being a causative or deleterious mutation. We used hereditary hemorrhagic telangiectasia (HHT) as a model for an autosomal dominant disease. Pedigree data were transferred to MLINK, and a Bayesian analysis was calculated to determine the likelihood that a variant is causative of disease. In applying this analysis to HHT pedigrees we found Bayes Factors of variants showing odds in favor of causality ranging from approximately 4:1 to over 400:1. These numbers provide an objective measure of the strength of genetic evidence. Other parameters such as amino acid severity predictions, ortholog and paralog comparisons and functional assays can be included in the analysis to increase the evidence of causality.     

Challenges of variant reinterpretation: Opinions of stakeholders and need for guidelines

PurposeThe knowledge used to classify genetic variants is continually evolving, and the classification can change on the basis of newly available data. Although up-to-date variant classification is essential for clinical management, reproductive planning, and identifying at-risk family members, there is no consistent practice across laboratories or clinicians on how or under what circumstances to perform variant reinterpretation.MethodsWe conducted exploratory focus groups (N = 142) and surveys (N = 1753) with stakeholders involved in the process of variant reinterpretation (laboratory directors, clinical geneticists, genetic counselors, nongenetic providers, and patients/parents) to assess opinions on key issues, including initiation of reinterpretation, variants to report, termination of the responsibility to reinterpret, and concerns about consent, cost, and liability.ResultsStakeholders widely agreed that there should be no fixed termination point to the responsibility to reinterpret a previously reported genetic variant. There were significant concerns about liability and lack of agreement about many logistical aspects of variant reinterpretation.ConclusionOur findings suggest a need to (1) develop consensus and (2) create transparency and awareness about the roles and responsibilities of parties involved in variant reinterpretation. These data provide a foundation for developing guidelines on variant reinterpretation that can aid in the development of a low-cost, scalable, and accessible approach.     

Genetic testing for BRCA1 and BRCA2 in the Province of Ontario

In 2001, genetic testing for BRCA1 and BRCA2 was introduced in Ontario, for women at high‐risk of breast or ovarian cancer. To date over 30,000 individuals have been tested throughout Ontario. Testing was offered to all Ontario residents who were eligible under any of 13 criteria. We report the results of tests conducted at Mount Sinai Hospital from 2007 to 2014. A total of 4726 individuals were tested, 764 (16.2%) were found to carry a pathogenic variant (mutation). Among 3684 women and men who underwent testing without a known familial BRCA mutation, 331 (9.0%) were found to carry a mutation. Among 1042 women and men tested for a known family mutation, 433 (41.6%) were positive. There were 603 female mutation carriers, of these, 303 were affected with breast or ovarian cancer (50%) and 16 with another cancer (2.3%). Of 284 unaffected female carriers, 242 (85%) were tested for a known family mutation and 42 (15%) were the first person in the family to be tested. By placing greater emphasis on recruiting unaffected female relatives of known mutation carriers for testing, greater than one‐half of newly identified carriers will be unaffected.     

Leveraging splice‐affecting variant predictors and a minigene validation system to identify Mendelian disease‐causing variants among exon‐captured variants of uncertain significance

The genetic heterogeneity of Mendelian disorders results in a significant proportion of patients that are unable to be assigned a confident molecular diagnosis after conventional exon sequencing and variant interpretation. Here, we evaluated how many patients with an inherited retinal disease (IRD) have variants of uncertain significance (VUS) that are disrupting splicing in a known IRD gene by means other than affecting the canonical dinucleotide splice site. Three in silico splice‐affecting variant predictors were leveraged to annotate and prioritize variants for splicing functional validation. An in vitro minigene system was used to assay each variant's effect on splicing. Starting with 745 IRD patients lacking a confident molecular diagnosis, we validated 23 VUS as splicing variants that likely explain disease in 26 patients. Using our results, we optimized in silico score cutoffs to guide future variant interpretation. Variants that alter base pairs other than the canonical GT‐AG dinucleotide are often not considered for their potential effect on RNA splicing but in silico tools and a minigene system can be utilized for the prioritization and validation of such splice‐disrupting variants. These variants can be overlooked causes of human disease but can be identified using conventional exon sequencing with proper interpretation guidelines.     

Classification and Clinical Management of Variants of Uncertain Significance in High Penetrance Cancer Predisposition Genes

In 2008, the International Agency for Research on Cancer (IARC) proposed a system for classifying sequence variants in highly penetrant breast and colon cancer susceptibility genes, linked to clinical actions. This system uses a multifactorial likelihood model to calculate the posterior probability that an altered DNA sequence is pathogenic. Variants between 5%–94.9% (class 3) are categorized as variants of uncertain significance (VUS). This interval is wide and might include variants with a substantial difference in pathogenicity at either end of the spectrum. We think that carriers of class 3 variants would benefit from a fine‐tuning of this classification. Classification of VUS to a category with a defined clinical significance is very important because for carriers of a pathogenic mutation full surveillance and risk‐reducing surgery can reduce cancer incidence. Counselees who are not carriers of a pathogenic mutation can be discharged from intensive follow‐up and avoid unnecessary risk‐reducing surgery. By means of examples, we show how, in selected cases, additional data can lead to reclassification of some variants to a different class with different recommendations for surveillance and therapy. To improve the clinical utility of this classification system, we suggest a pragmatic adaptation to clinical practice.     

The dawn of consumer-directed testing

As the public's interest in genetics and genomics has increased, there has been corresponding and unprecedented growth in direct-to-consumer genetic testing (DTC-GT). Although regulatory concerns have limited true DTC-GT available without a physician order, the paradigm has shifted to a model of consumer-directed genetic testing (CD-GT) in which patients are researching testing options and requesting specific genetic testing from their health-care providers. However, many nongenetics health-care providers do not have the background, education, interest, or time to order and/or interpret typical clinical genetic testing, let alone DTC-GT. The lines between CD-GT, DTC-GT, and traditional clinical genetic testing are also blurring with the same types of tests available in different settings (e.g., carrier screening) and tests merging medical and nonmedical results, increasing the complexity for consumer decision-making and clinician management. The genetics community has the training to work with CD-GT, but there has been a hesitancy to commit to working with these results and questions about what to do when consumers have more complicated asks, like interpretation of raw data. Additionally, at the rate with which CD-GT is growing, there are questions about having sufficient genetics professionals to meet the potential genetic counseling demand. While there are many complex questions and challenges, this market represents a chance for the genetics community to address and unmet need. We will review the history of the CD-GT/DTC-GT market and outline the issues and opportunities our profession is facing.     

Genetic predisposition to colorectal cancer: syndromes,genes, classification of genetic variants and implications for precision medicine

This article reviews genes and syndromes associated with predisposition to colorectal cancer (CRC), with an overview of gene variant classification. We include updates on the application of preventive and therapeutic measures, focusing on the use of non-steroidal anti-inflammatory drugs (NSAIDs) and immunotherapy. Germline pathogenic variants in genes conferring high or moderate risk to cancer are detected in 6–10% of all CRCs and 20% of those diagnosed before age 50. CRC syndromes can be subdivided into nonpolyposis and polyposis entities, the most common of which are Lynch syndrome and familial adenomatous polyposis, respectively. In addition to known and novel genes associated with highly penetrant CRC risk, identification of pathogenic germline variants in genes associated with moderate-penetrance cancer risk and/or hereditary cancer syndromes not traditionally linked to CRC may have an impact on genetic testing, counseling, and surveillance. The use of multigene panels in genetic testing has exposed challenges in the classification of variants of uncertain significance. We provide an overview of the main classification systems and strategies for improving these. Finally, we highlight approaches for integrating chemoprevention in the care of individuals with genetic predisposition to CRC and use of targeted agents and immunotherapy for treatment of mismatch repair-deficient and hypermutant tumors. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Adding In Silico Assessment of Potential Splice Aberration to the Integrated Evaluation of BRCA Gene Unclassified Variants

Clinical mutation screening of the cancer susceptibility genes BRCA1 and BRCA2 generates many unclassified variants (UVs). Most of these UVs are either rare missense substitutions or nucleotide substitutions near the splice junctions of the protein coding exons. Previously, we developed a quantitative method for evaluation of BRCA gene UVs—the “integrated evaluation”—that combines a sequence analysis‐based prior probability of pathogenicity with patient and/or tumor observational data to arrive at a posterior probability of pathogenicity. One limitation of the sequence analysis‐based prior has been that it evaluates UVs from the perspective of missense substitution severity but not probability to disrupt normal mRNA splicing. Here, we calibrated output from the splice‐site fitness program MaxEntScan to generate spliceogenicity‐based prior probabilities of pathogenicity for BRCA gene variants; these range from 0.97 for variants with high probability to damage a donor or acceptor to 0.02 for exonic variants that do not impact a splice junction and are unlikely to create a de novo donor. We created a database http://priors.hci.utah.edu/PRIORS/ that provides the combined missense substitution severity and spliceogenicity‐based probability of pathogenicity for BRCA gene single‐nucleotide substitutions. We also updated the BRCA gene Ex‐UV LOVD, available at http://hci‐exlovd.hci.utah.edu, with 77 re‐evaluable variants.     

Genome‐wide DNA methylation and RNA analyses enable reclassification of two variants of uncertain significance in a patient with clinical Kabuki syndrome

Nontruncating sequence variants represent a major challenge in variant interpretation and classification. Here, we report a patient with features of Kabuki syndrome who carries two rare heterozygous variants in KMT2D: c.12935C>T, p.(Ser4312Phe) and c.15785‐10T>G. The clinical significance of these variants were discordantly interpreted by different diagnostic laboratories. Parental testing showed that the missense variant was inherited from the father with a mild Kabuki phenotype and the intronic variant from the mother with mosaic status. Through genome‐wide DNA methylation analysis of peripheral blood, we confirmed that the proband exhibited a previously described episignature of Kabuki syndrome. Parental samples had normal DNA methylation profiles, thus ruling out the involvement of the paternally inherited missense variant. RNA analysis revealed that the intronic change resulted in exon 49 skipping and frameshift, thereby providing a molecular diagnosis of Kabuki syndrome. This study demonstrates the utility of epigenomic and RNA analyses in resolving ambiguous clinical cases.     

Cholesterol metabolism is a potential therapeutic target for Rett syndrome

Genetic testing has the potential to guide the prevention and treatment of disease in a variety of settings, and recent technical advances have greatly increased our ability to acquire large amounts of genetic data. The interpretation of this data remains challenging, as the clinical significance of genetic variation detected in the laboratory is not always clear. Although regulatory agencies and professional societies provide some guidance regarding the classification, reporting, and long‐term follow‐up of variants, few protocols for the implementation of these guidelines have been described. Because the primary aim of clinical testing is to provide results to inform medical management, a variant classification program that offers timely, accurate, confident and cost‐effective interpretation of variants should be an integral component of the laboratory process. Here we describe the components of our laboratory's current variant classification program (VCP), based on 20 years of experience and over one million samples tested, using the BRCA1/2 genes as a model. Our VCP has lowered the percentage of tests in which one or more BRCA1/2 variants of uncertain significance (VUSs) are detected to 2.1% in the absence of a pathogenic mutation, demonstrating how the coordinated application of resources toward classification and reclassification significantly impacts the clinical utility of testing.     

Systematic review of the empirical investigation of resources to support decision-making regarding BRCA1 and BRCA2 genetic testing in women with breast cancer

Objective

Identify existing resources developed and/or evaluated empirically in the published literature designed to support women with breast cancer making decisions regarding genetic testing for BRCA1/2 mutations.

'Indirect' BRCA1/2 testing: a useful approach in hereditary breast and ovarian cancer families without a living affected relative

We report an approach for BRCA1/2 testing whereby genetic testing can be offered to families at high risk of hereditary breast and ovarian cancer but where no DNA from affected relatives is available. By testing two or more unaffected relatives at 50% risk of being heterozygous for a potential BRCA1/2 mutation, there is a chance of up to 99% of finding a mutation that would have been detectable in an affected individual from the same family. The overall likelihood of identifying a mutation is dependent on the family history, and therefore 'indirect' testing would be most applicable for families with a very high risk of carrying a BRCA1/2 mutation. Using this approach also requires balancing issues of testing resource limitations, family dynamics and adequate preparation of unaffected persons for a positive test, with the advantages of targeting screening and prophylactic surgery.     

Development and validation of an instrument to measure the impact of genetic testing on self-concept in Lynch syndrome

A positive genetic test result may impact on a person's self-concept and affect quality of life. The purpose of the study was to develop a self-concept scale to measure such impact for individuals carrying mutations for a heritable colorectal cancer Lynch syndrome (LS). Two distinct phases were involved: Phase 1 generated specific colorectal self-concept candidate scale items from interviews with eight LS carriers and five genetic counselors, which were added to a previously developed self-concept scale for BRCA1/2 mutation carriers, Phase II had 115 LS carriers complete the candidate scale and a battery of validating measures. A 20-item scale was developed with two dimensions identified through factor analysis: stigma/vulnerability and bowel symptom-related anxiety. The scale showed excellent reliability (Cronbach's α = 0.93), good convergent validity by a high correlation with impact of event scale (r(102) = 0.55, p < 0.001) and Rosenberg self-esteem scale (r(108) = -0.59, p < 0.001), and a low correlation with the Fear questionnaire (r(108) = 0.37, p < 0.001). The scale's performance was stable across participant characteristics. This new scale for measuring self-concept has potential to be used as a clinical tool and as a measure for future studies.