Kristy Lee

Actionable exomic incidental findings in 6503 participants: challenges of variant classification

Recommendations for laboratories to report incidental findings from genomic tests have stimulated interest in such results. In order to investigate the criteria and processes for assigning the pathogenicity of specific variants and to estimate the frequency of such incidental findings in patients of European and African ancestry, we classified potentially actionable pathogenic single-nucleotide variants (SNVs) in all 4300 European- and 2203 African-ancestry participants sequenced by the NHLBI Exome Sequencing Project (ESP). We considered 112 gene-disease pairs selected by an expert panel as associated with medically actionable genetic disorders that may be undiagnosed in adults. The resulting classifications were compared to classifications from other clinical and research genetic testing laboratories, as well as with in silico pathogenicity scores. Among European-ancestry participants, 30 of 4300 (0.7%) had a pathogenic SNV and six (0.1%) had a disruptive variant that was expected to be pathogenic, whereas 52 (1.2%) had likely pathogenic SNVs. For African-ancestry participants, six of 2203 (0.3%) had a pathogenic SNV and six (0.3%) had an expected pathogenic disruptive variant, whereas 13 (0.6%) had likely pathogenic SNVs. Genomic Evolutionary Rate Profiling mammalian conservation score and the Combined Annotation Dependent Depletion summary score of conservation, substitution, regulation, and other evidence were compared across pathogenicity assignments and appear to have utility in variant classification. This work provides a refined estimate of the burden of adult onset, medically actionable incidental findings expected from exome sequencing, highlights challenges in variant classification, and demonstrates the need for a better curated variant interpretation knowledge base.

An informatics approach to analyzing the incidentalome

Purpose:Next-generation sequencing has transformed genetic research and is poised to revolutionize clinical diagnosis. However, the vast amount of data and inevitable discovery of incidental findings require novel analytic approaches. We therefore implemented for the first time a strategy that utilizes an a priori structured framework and a conservative threshold for selecting clinically relevant incidental findings.Methods:We categorized 2,016 genes linked with Mendelian diseases into “bins” based on clinical utility and validity, and used a computational algorithm to analyze 80 whole-genome sequences in order to explore the use of such an approach in a simulated real-world setting.Results:The algorithm effectively reduced the number of variants requiring human review and identified incidental variants with likely clinical relevance. Incorporation of the Human Gene Mutation Database improved the yield for missense mutations but also revealed that a substantial proportion of purported disease-causing mutations were misleading.Conclusion:This approach is adaptable to any clinically relevant bin structure, scalable to the demands of a clinical laboratory workflow, and flexible with respect to advances in genomics. We anticipate that application of this strategy will facilitate pretest informed consent, laboratory analysis, and posttest return of results in a clinical context.Genet Med 2013:15(1):36–44

Whole-genome and whole-exome sequencing in hereditary cancer: impact on genetic testing and counseling.

AbstractThe incorporation of whole-genome and whole-exome sequencing into clinical practice will undoubtedly change the way genetic counselors and other clinicians approach genetic testing. Enabling the analysis of essentially all human genes in one comprehensive test, this new technology can result in reduced testing cost and time to diagnosis. Another consequence of this broad scope, however, is the increased amount, complexity, and variety of results a clinician may need to discuss with a patient. The purpose of this article is to review the technology and outline some of the benefits and challenges of whole-genome and whole-exome sequencing in hereditary cancer practice.

A standardized, evidence-based protocol to assess clinical actionability of genetic disorders associated with genomic variation.

Purpose:Genome and exome sequencing can identify variants unrelated to the primary goal of sequencing. Detecting pathogenic variants associated with an increased risk of a medical disorder enables clinical interventions to improve future health outcomes in patients and their at-risk relatives. The Clinical Genome Resource, or ClinGen, aims to assess clinical actionability of genes and associated disorders as part of a larger effort to build a central resource of information regarding the clinical relevance of genomic variation for use in precision medicine and research.Methods:We developed a practical, standardized protocol to identify available evidence and generate qualitative summary reports of actionability for disorders and associated genes. We applied a semiquantitative metric to score actionability.Results:We generated summary reports and actionability scores for the 56 genes and associated disorders recommended by the American College of Medical Genetics and Genomics for return as secondary findings from clinical genome-scale sequencing. We also describe the challenges that arose during the development of the protocol that highlight important issues in characterizing actionability across a range of disorders.Conclusion:The ClinGen framework for actionability assessment will assist research and clinical communities in making clear, efficient, and consistent determinations of actionability based on transparent criteria to guide analysis and reporting of findings from clinical genome-scale sequencing.Genet Med 18 12, 1258–1268.

A semiquantitative metric for evaluating clinical actionability of incidental or secondary findings from genome-scale sequencing.

Purpose:As genome-scale sequencing is increasingly applied in clinical scenarios, a wide variety of genomic findings will be discovered as secondary or incidental findings, and there is debate about how they should be handled. The clinical actionability of such findings varies, necessitating standardized frameworks for a priori decision making about their analysis.Methods:We established a semiquantitative metric to assess five elements of actionability: severity and likelihood of the disease outcome, efficacy and burden of intervention, and knowledge base, with a total score from 0 to 15.Results:The semiquantitative metric was applied to a list of putative actionable conditions, the list of genes recommended by the American College of Medical Genetics and Genomics (ACMG) for return when deleterious variants are discovered as secondary/incidental findings, and a random sample of 1,000 genes. Scores from the list of putative actionable conditions (median = 12) and the ACMG list (median = 11) were both statistically different than the randomly selected genes (median = 7) (P < 0.0001, two-tailed Mann-Whitney test).Conclusion:Gene–disease pairs having a score of 11 or higher represent the top quintile of actionability. The semiquantitative metric effectively assesses clinical actionability, promotes transparency, and may facilitate assessments of clinical actionability by various groups and in diverse contexts.Genet Med 18 5, 467–475.

Navigating the current landscape of clinical genetic testing for inherited retinal dystrophies

Inherited eye disorders are a significant cause of vision loss. Genetic testing can be particularly helpful for patients with inherited retinal dystrophies because of genetic heterogeneity and overlapping phenotypes. The need to identify a molecular diagnosis for retinal dystrophies is particularly important in the era of developing novel gene therapy–based treatments, such as the RPE65 gene–based clinical trials and others on the horizon, as well as recent advances in reproductive options. The introduction of massively parallel sequencing technologies has significantly advanced the identification of novel gene candidates and has expanded the landscape of genetic testing. In a relatively short time clinical medicine has progressed from limited testing options to a plethora of choices ranging from single-gene testing to whole-exome sequencing. This article outlines currently available genetic testing and factors to consider when selecting appropriate testing for patients with inherited retinal dystrophies.Genet Med 17 4, 245–252.

A Genetic Counselor’s Guide to Using Next-Generation Sequencing in Clinical Practice

Advances in next-generation sequencing (NGS) and rapid reductions in cost have increased the use of such technologies in research and clinical practice. However, many barriers exist to translating NGS for routine clinical use, including issues related to the interpretation of results, and the potential to find results that are secondary or incidental to the specific application of NGS. Nonetheless, NGS has become sufficiently affordable to be offered by several clinical laboratories, and increasingly it is becoming an attractive and viable option for clinicians and patients. This article reviews current NGS technologies, highlighting the information genetic counselors need to know to make informed-decisions about utilizing NGS in the clinic, and underscoring the impact of this new testing modality on the practice of genetic counseling.

High Diagnostic Yield of Whole Exome Sequencing in Participants With Retinal Dystrophies in a Clinical Ophthalmology Setting

PURPOSE To assess the diagnostic yield and the practicality of implementing whole exome sequencing within a clinical ophthalmology setting. DESIGN Evaluation of a diagnostic protocol. METHODS setting: Patient participants were enrolled during clinical appointments in a university-based ophthalmic genetics clinic. PATIENT POPULATION Twenty-six patients with a variety of presumed hereditary retinal dystrophies. INTERVENTION Participants were offered whole exome sequencing in addition to clinically available sequencing gene panels between July 2012 and January 2013 to determine the molecular etiology of their retinal dystrophy. MAIN OUTCOME MEASURES Diagnostic yield and acceptability of whole exome sequencing in patients with retinal disorders. RESULTS Twenty-six of 29 eligible patients (∼90%) who were approached opted to undergo molecular testing. Each participant chose whole exome sequencing in addition to, or in lieu of, clinically available sequencing gene panels. Time to obtain informed consent was manageable in the clinical context. Whole exome sequencing successfully identified known pathogenic mutations or suspected deleterious variants in 57.7% of participants. Additionally, 1 participant had 2 autosomal dominant medically actionable incidental findings (unrelated to retinopathy) that were reported to enable the participant to take preventive action and reduce risk for future disease. CONCLUSIONS In this study, we identified the molecular etiology for more than half of all participants. Additionally, we found that participants were widely accepting of whole exome sequencing and the possibility of being informed about medically actionable incidental findings.

The who, what, and why of research participants’ intentions to request a broad range of secondary findings in a diagnostic genomic sequencing study

PurposeIn a diagnostic exome sequencing study (the North Carolina Clinical Genomic Evaluation by Next-Generation Exome Sequencing project, NCGENES), we investigated adult patients’ intentions to request six categories of secondary findings (SFs) with low or no medical actionability and correlates of their intentions.MethodsAt enrollment, eligible participants (n = 152) completed measures assessing their sociodemographic, clinical, and literacy-related characteristics. Prior to and during an in-person diagnostic result disclosure visit, they received education about categories of SFs they could request. Immediately after receiving education at the visit, participants completed measures of intention to learn SFs, interest in each category, and anticipated regret for learning and not learning each category.ResultsSeventy-eight percent of participants intended to learn at least some SFs. Logistic regressions examined their intention to learn any or all of these findings (versus none) and interest in each of the six individual categories (yes/no). Results revealed little association between intentions and sociodemographic, clinical, or literacy-related factors. Across outcomes, participants who anticipated regret for learning SFs reported weaker intention to learn them (odds ratios (ORs) from 0.47 to 0.71), and participants who anticipated regret for not learning these findings reported stronger intention to learn them (OR 1.61–2.22).ConclusionIntentions to request SFs with low or no medical actionability may be strongly influenced by participants’ desire to avoid regret.

Specifications of the ACMG/AMP variant curation guidelines for the analysis of germline CDH1 sequence variants

The variant curation guidelines published in 2015 by the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) provided the genetics community with a framework to assess variant pathogenicity; however, these rules are not gene specific. Germline pathogenic variants in the CDH1 gene cause hereditary diffuse gastric cancer and lobular breast cancer, a clinically challenging cancer predisposition syndrome that often requires a multidisciplinary team of experts to be properly managed. Given this challenge, the Clinical Genome Resource (ClinGen) Hereditary Cancer Domain prioritized the development of the CDH1 variant curation expert panel (VCEP) to develop and implement rules for CDH1 variant classifications. Here, we describe the CDH1 specifications of the ACMG/AMP guidelines, which were developed and validated after a systematic evaluation of variants obtained from a cohort of clinical laboratory data encompassing ∼827,000 CDH1 sequenced alleles. Comparing previously reported germline variants that were classified using the 2015 ACMG/AMP guidelines to the CDH1 VCEP recommendations resulted in reduced variants of uncertain significance and facilitated resolution of variants with conflicted assertions in ClinVar. The ClinGen CDH1 VCEP recommends the use of these CDH1‐specific guidelines for the assessment and classification of variants identified in this clinically actionable gene.