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The increased use of next-generation sequencing has expanded our understanding of the involvement and prevalence of mosaicism in genetic disorders. We describe a total of eleven cases: nine in which mosaic variants detected by genome sequencing (GS) and/or targeted gene panels (TGPs) were considered to be causative for the proband's phenotype, and two of apparent parental mosaicism. Variants were identified in the following genes: PHACTR1, SCN8A, KCNT1, CDKL5, NEXMIF, CUX1, TSC2, GABRB2, and SMARCB1. In addition, we identified one large duplication including three genes, UBE3A, GABRB3, and MAGEL2, and one large deletion including deletion of ARFGAP1, EEF1A2, CHRNA4, and KCNQ2. All patients were enrolled in the NYCKidSeq study, a research program studying the communication of genomic information in clinical care, as well as the clinical utility and diagnostic yield of GS for children with suspected genetic disorders in diverse populations in New York City. We observed variability in the correlation between reported variant allele fraction and the severity of the patient's phenotype, although we were not able to determine the mosaicism percentage in clinically relevant tissue(s). Although our study was not sufficiently powered to assess differences in mosaicism detection between the two testing modalities, we saw a trend toward better detection by GS as compared with TGP testing. This case series supports the importance of mosaicism in childhood-onset genetic conditions and informs guidelines for laboratory and clinical interpretation of mosaic variants detected by GS.

Genomic sequencing results need to be effectively communicated across all populations and practice settings. Projects in the Clinical Sequencing Evidence-Generating Research (CSER) consortium enroll diverse racial/ethnic and medically underserved participants across various clinical contexts. This article explores a set of CSER results disclosure cases to expand the evidence base on experiences returning genomic results. Case details were collected using a structured set of questions. We identified common themes in the case set, and assessed challenges and strategies in achieving six relevant results disclosure objectives. CSER-affiliated patient/community stakeholder impressions of the findings were solicited via video conference calls. Seventeen cases across six CSER projects were included. Case themes sorted into four categories: (1) factors influencing participant understanding, (2) participant emotional response, (3) disease burden, and (4) logistical challenges. Challenges meeting results disclosure objectives included a lack of dialogue, health literacy level, unexpected findings, and complex concepts. Strategies were consistent with traditional genetic counseling practice, but also highlighted approaches being evaluated in CSER projects. Patient/community stakeholders supported the identified themes and provided additional suggestions to improve patient understanding and engagement. These experiences add valuable insights into adapting genomic results disclosure practices to best serve all patient populations.

The descriptor 'usual care' refers to standard or routine care. Yet, no formal definition exists. The need to define what constitutes usual care arises in clinical research. Often one arm in a trial represents usual care in comparison with a novel intervention. Accordingly, usual care in genetic counseling research appears predominantly in randomized controlled trials. Recent standards for reporting genetic counseling research call for standardization, but do not address usual care. We (1) inventoried all seven studies in the Clinical Sequencing Evidence-Generating Consortium (CSER) about how genetic counseling was conceptualized, conducted, and whether a usual care arm was involved; (2) conducted a review of published randomized control trials in genetic counseling, comparing how researchers describe usual care groups; and (3) reviewed existing professionally endorsed definitions and practice descriptions of genetic counseling. We found wide variation in the content and delivery of usual care. Descriptions frequently detailed the content of usual care, most often noting assessment of genetic risk factors, collecting family histories, and offering testing. A minority included addressing psychological concerns or the risks versus benefits of testing. Descriptions of how care was delivered were vague except for mode and type of clinician, which varied. This significant variation, beyond differences expected among subspecialties, reduces the validity and generalizability of genetic counseling research. Ideally, research reflects clinical practice so that evidence generated can be used to improve clinical outcomes. To address this objective, we propose a definition of usual care in genetic counseling research that merges common elements from the National Society of Genetic Counselors' practice definition, the Reciprocal Engagement Model, and the Accreditation Council for Genetic Counselors' practice-based competencies. Promoting consistent execution of usual care in the design of genetic counseling trials can lead to more consistency in representing clinical care and facilitate the generation of evidence to improve it.

Pathogenic variants inBRCA1andBRCA2(BRCA1/2) lead to increased risk of breast, ovarian, and other cancers, but most variant positive individuals in the general population are unaware of their risk, and little is known about the prevalence of pathogenicBRCA1/2variants in non-European populations. We investigatedBRCA1/2prevalence and impact using exome sequencing and electronic health record (EHR) data from 30,223 adult participants of the BioMeBiobank in New York City. There were 218 (0.7%) individuals harboring expected pathogenic variants, resulting in an overall prevalence of 1 in 139. In sub-populations defined by genetic ancestry, the highest prevalence was in individuals of Ashkenazi Jewish (AJ; 1 in 49), Filipino and Southeast Asian (1 in 81), and Non-AJ European (1 in 103) descent. Among 218 variant positive individuals, 112 (51.4%) harbored known founder variants: 80 had AJ founder variants (BRCA1c.5266dupC and c.68_69delAG, andBRCA2c.5946delT), 7 had a Puerto Rican founder variant (BRCA2c.3922G>T), and 25 had one of 19 other founder variants. Non-European populations were more likely to harborBRCA1/2variants that were not classified in ClinVar, or that had uncertain or conflicting evidence for pathogenicity. Within mixed ancestry populations, such as Hispanic/Latinos with genetic ancestry from Africa, Europe, and the Americas, there was a strong correlation between the proportion African genetic ancestry and the likelihood of harboring aBRCA1/2variant with uncertain or conflicting evidence for pathogenicity. Based on EHR and participant questionnaire data, ∼28% of variant positive individuals had a personal history, and ∼45% a personal or family history ofBRCA1/2-associated cancers. Approximately 27% of variant positive individuals had evidence of prior clinical genetic testing forBRCA1/2. However, individuals with AJ founder variants were twice as likely to have had a clinical test (38%) than those with other pathogenic variants (19%). These findings deepen our knowledge aboutBRCA1/2variants and associated cancer risk in diverse populations, indicate a gap in knowledge about potential cancer-related variants in non-European populations, and suggest that genomic screening in diverse patient populations may be an effective tool to identify at-risk individuals.

Summary: Genetic counselors are trained to deliver complicated genomic test results to parents of pediatric patients. However, there is limited knowledge on how parents perceive this information and what they understand about the results. This research aims to qualitatively explore parents’ experiences receiving genomic test results for their children. As part of formative research for the NYCKidSeq Study, we recruited a purposive sample of parents of 22 children stratified by child race/ethnicity and test result classification (positive, uncertain, or negative) and conducted in-depth interviews using a semi-structured guide. Analysis was conducted using grounded theory’s constant comparative method across cases and themes. Parents described different elements of understanding: genetics knowledge; significance and meaning of positive, uncertain, or negative results; and implications for the health of their child and family. Parents reported challenges understanding technical details and significance of their child’s results but gladly allowed their providers to be custodians of this information. However, of the different elements of understanding described, parents cared most deeply about being able to understand implications for their child’s and family’s health. These findings suggest that a counseling approach that primarily addresses parents’ desire to understand how to best care for their child and family may be more appropriate than an information-heavy approach focused on technical details. Further research is warranted to confirm these findings in larger parent cohorts and to explore ways genetic counseling can support parents’ preferences without sacrificing important components of parent understanding and overall satisfaction with their experiences with genomic medicine.

Achieving confidence in the causality of a disease locus is a complex task that often requires supporting data from both statistical genetics and clinical genomics. Here we describe a combined approach to identify and characterize a genetic disorder that leverages distantly related patients in a health system and population-scale mapping. We utilize genomic data to uncover components of distant pedigrees, in the absence of recorded pedigree information, in the multi-ethnic BioMe biobank in New York City. By linking to medical records, we discover a locus associated with both elevated genetic relatedness and extreme short stature. We link the gene, COL27A1, with a little-known genetic disease, previously thought to be rare and recessive. We demonstrate that disease manifests in both heterozygotes and homozygotes, indicating a common collagen disorder impacting up to 2% of individuals of Puerto Rican ancestry, leading to a better understanding of the continuum of complex and Mendelian disease., eLife digest Diseases often run in families. These disease are frequently linked to changes in DNA that are passed down through generations. Close family members may share these disease-causing mutations; so may distant relatives who inherited the same mutation from a common ancestor long ago. Geneticists use a method called linkage mapping to trace a disease found in multiple members of a family over generations to genetic changes in a shared ancestor. This allows scientists to pinpoint the exact place in the genome the disease-causing mutation occurred. Using computer algorithms, scientists can apply the same technique to identify mutations that distant relatives inherited from a common ancestor. Belbin et al. used this computational technique to identify a mutation that may cause unusually short stature or bone and joint problems in up to 2% of people of Puerto Rican descent. In the experiments, the genomes of about 32,000 New Yorkers who have volunteered to participate in the BioMe Biobank and their health records were used to search for genetic changes linked to extremely short stature. The search revealed that people who inherited two copies of this mutation from their parents were likely to be extremely short or to have bone and joint problems. People who inherited one copy had an increased likelihood of joint or bone problems. This mutation affects a gene responsible for making a form of protein called collagen that is important for bone growth. The analysis suggests the mutation first arose in a Native American ancestor living in Puerto Rico around the time that European colonization began. The mutation had previously been linked to a disorder called Steel syndrome that was thought to be rare. Belbin et al. showed this condition is actually fairly common in people whose ancestors recently came from Puerto Rico, but may often go undiagnosed by their physicians. The experiments emphasize the importance of including diverse populations in genetic studies, as studies of people of predominantly European descent would likely have missed the link between this disease and mutation.

Patients, clinicians, researchers and payers are seeking to understand the value of using genomic information (as reflected by genotyping, sequencing, family history or other data) to inform clinical decision-making. However, challenges exist to widespread clinical implementation of genomic medicine, a prerequisite for developing evidence of its real-world utility. To address these challenges, the National Institutes of Health-funded IGNITE (Implementing GeNomics In pracTicE; www.ignite-genomics.org ) Network, comprised of six projects and a coordinating center, was established in 2013 to support the development, investigation and dissemination of genomic medicine practice models that seamlessly integrate genomic data into the electronic health record and that deploy tools for point of care decision making. IGNITE site projects are aligned in their purpose of testing these models, but individual projects vary in scope and design, including exploring genetic markers for disease risk prediction and prevention, developing tools for using family history data, incorporating pharmacogenomic data into clinical care, refining disease diagnosis using sequence-based mutation discovery, and creating novel educational approaches. This paper describes the IGNITE Network and member projects, including network structure, collaborative initiatives, clinical decision support strategies, methods for return of genomic test results, and educational initiatives for patients and providers. Clinical and outcomes data from individual sites and network-wide projects are anticipated to begin being published over the next few years. The IGNITE Network is an innovative series of projects and pilot demonstrations aiming to enhance translation of validated actionable genomic information into clinical settings and develop and use measures of outcome in response to genome-based clinical interventions using a pragmatic framework to provide early data and proofs of concept on the utility of these interventions. Through these efforts and collaboration with other stakeholders, IGNITE is poised to have a significant impact on the acceleration of genomic information into medical practice.