Bradford C. Powell

Yield of reported results from genetic testing provides a proximal measure of clinical usefulness. While ACMG/AMP guidelines provide representations of uncertainty for individual genetic variant classification, additional factors are considered when determining whether results explain a patient's presentation. To standardize cross-consortium analysis, a working group of the Clinical Sequencing Evidence-Generating Research (CSER2) consortium iteratively identified factors used when contextualizing variant-level results to case-level interpretation (i.e., interpretation of an individual's genetic data with respect to the indication for testing). Sites independently categorized results; complex cases were discussed collaboratively, leading to revision of classification categories. Our metric incorporates factors beyond classification of reported variants. Analogous to variant-level results, "Definitive Positive" and "Probable Positive" represent certainty that results may be clinically explanatory. The category "Inconclusive" applies when results may or may not fully explain the patient presentation, with subdivision into multiple (non-exclusive) subcategories. Cases falling outside all of the other categories are considered "Negative". The overall diagnostic yield by this metric and use of categories for inconclusive results varied by CSER project, in part paralleling study design differences. This case-level categorization provides a meaningful assessment of diagnostic yield, and for inconclusive cases identifies potentially resolvable factors for case resolution.

We report 21 families displaying neurodevelopmental differences and multiple congenital anomalies while bearing a series of rare variants in mitogen-activated protein kinase kinase kinase kinase 4 ( MAP4K4 ). MAP4K4 has been implicated in many signaling pathways including c-Jun N-terminal and RAS kinases and is currently under investigation as a druggable target for multiple disorders. Using several zebrafish models, we demonstrate that these human variants are either loss-of-function or dominant-negative alleles and show that decreasing Map4k4 activity causes developmental defects. Furthermore, MAP4K4 can restrain hyperactive RAS signaling in early embryonic stages. Together, our data demonstrate that MAP4K4 negatively regulates RAS signaling in the early embryo and that variants identified in affected humans abrogate its function, establishing MAP4K4 as a causal locus for individuals with syndromic neurodevelopmental differences.

Actionability is an important concept in medicine that does not have a well-accepted standard definition, nor is there a general consensus on how to establish it. Medical actionability is often conflated with clinical utility, a related but distinct concept. This lack of clarity contributes to practice variation and inconsistent coverage decisions in genomic medicine, leading to the potential for systematic bias in the use of evidence-based interventions. We clarify how medical actionability and clinical utility are distinct and then discuss the spectrum of actionability, including benefits for the person, the family, and society. We also describe applications across the life course, including prediction, diagnosis, and treatment. Current challenges in assessing the medical actionability of identified genomic variants include gaps in the evidence, limited contexts with practice guidelines, and subjective aspects of medical actionability. A standardized and authoritative assessment of medical actionability is critical to implementing genomic medicine in a fashion that improves population health outcomes and reduces health disparities.

What’s already known about this topic?: Sequencing-based noninvasive testing can detect large copy number abnormalities and some auto-somal dominant single-gene disorders Exome sequencing (ES) on fetal samples provides 20% diagnostic yield for structural abnormalities after normal karyotype & microarray What does this study add?: ES on cell-free DNA in three gravid patients with suspected genetic disease in the fetus We demonstrate broad sequencing approaches are limited by sampling and technical difficulties, concluding broad sequencing is currently inappropriate for noninvasive testing

Background: The 2015 American College of Medical Genetics and Genomics (ACMG) and Association for Molecular Pathology (AMP) guidelines for clinical sequence variant interpretation state that “well-established” functional studies can be used as evidence in variant classification. These guidelines articulated key attributes of functional data, including that assays should reflect the biological environment and be analytically sound; however, details of how to evaluate these attributes were left to expert judgment. The Clinical Genome Resource (ClinGen) designates Variant Curation Expert Panels (VCEPs) in specific disease areas to make gene-centric specifications to the ACMG/AMP guidelines, including more specific definitions of appropriate functional assays. We set out to evaluate the existing VCEP guidelines for functional assays. Methods: We evaluated the functional criteria (PS3/BS3) of six VCEPs ( CDH1 , Hearing Loss, Inherited Cardiomyopathy- MYH7, PAH, PTEN , RASopathy). We then established criteria for evaluating functional studies based on disease mechanism, general class of assay, and the characteristics of specific assay instances described in primary literature. Using these criteria, we extensively curated assay instances cited by each VCEP in their pilot variant classification to analyze VCEP recommendations and their use in the interpretation of functional studies. Results: Unsurprisingly, our analysis highlighted the breadth of VCEP-approved assays, reflecting the diversity of disease mechanisms among VCEPs. We also noted substantial variability between VCEPs in the method used to select these assays and in the approach used to specify strength modifications, as well as differences in suggested validation parameters. Importantly, we observed discrepancies between the parameters VCEPs specified as required for approved assay instances and the fulfillment of these requirements in the individual assays cited in pilot variant interpretation. Conclusions: Interpretation of the intricacies of functional assays often requires expert-level knowledge of the gene and disease and current VCEP recommendations for functional assay evidence are a useful tool to improve the accessibility of functional data. However, our analysis suggests that further guidance is needed to standardize this process and ensure consistency in the application of functional evidence.

Using next-generation sequencing (NGS) in newborn screening (NBS) could expand the number of genetic conditions detected pre-symptomatically, simultaneously challenging current precedents, raising ethical concerns, and extending the role of parental decision-making in NBS. The NC NEXUS (Newborn Exome Sequencing for Universal Screening) study seeks to assess the technical possibilities and limitations of NGS-NBS, devise and evaluate a framework to convey various types of genetic information, and develop best practices for incorporating NGS-NBS into clinical care. The study is enrolling both a healthy cohort and a cohort diagnosed with known disorders identified through recent routine NBS. It uses a novel age-based metric to categorize a priori the large amount of data generated by NGS-NBS and interactive online decision aids to guide parental decision-making. Primary outcomes include: (1) assessment of NGS-NBS sensitivity, (2) decision regret, and (3) parental decision-making about NGS-NBS, and, for parents randomized to have the option of requesting them, additional findings (diagnosed and healthy cohorts). Secondary outcomes assess parents' reactions to the study and to decision-making. Participants are parents and children in a well-child cohort recruited from a prenatal clinic and a diagnosed cohort recruited from pediatric clinics that treat children with disorders diagnosed through traditional NBS (goal of 200 children in each cohort). In phase 1, all parent participants use an online decision aid to decide whether to accept NGS-NBS for their child and provide consent for NGS-NBS. In phase 2, parents who consent to NGS-NBS are randomized to a decision arm or control arm (2:1 allocation) and learn their child's NGS-NBS results, which include conditions from standard (non-NGS) NBS plus other highly actionable childhood-onset conditions. Parents in the decision arm use a second decision aid to make decisions about additional results from their child's sequencing. In phase 3, decision arm participants learn additional results they have requested. Online questionnaires are administered at up to five time points. NC NEXUS will use a rigorous interdisciplinary approach designed to collect rich data to inform policy, practice, and future research. clinicaltrials.gov, NCT02826694 . Registered on 11 July, 2016.