Nanopore sequencing of 1000 Genomes Project samples to build a comprehensive catalog of human genetic variation.

Less than half of individuals with a suspected Mendelian condition receive a precise molecular diagnosis after comprehensive clinical genetic testing. Improvements in data quality and costs have heightened interest in using long-read sequencing (LRS) to streamline clinical genomic testing, but the absence of control datasets for variant filtering and prioritization has made tertiary analysis of LRS data challenging. To address this, the 1000 Genomes Project ONT Sequencing Consortium aims to generate LRS data from at least 800 of the 1000 Genomes Project samples. Our goal is to use LRS to identify a broader spectrum of variation so we may improve our understanding of normal patterns of human variation. Here, we present data from analysis of the first 100 samples, representing all 5 superpopulations and 19 subpopulations. These samples, sequenced to an average depth of coverage of 37x and sequence read N50 of 54 kbp, have high concordance with previous studies for identifying single nucleotide and indel variants outside of homopolymer regions. Using multiple structural variant (SV) callers, we identify an average of 24,543 high-confidence SVs per genome, including shared and private SVs likely to disrupt gene function as well as pathogenic expansions within disease-associated repeats that were not detected using short reads. Evaluation of methylation signatures revealed expected patterns at known imprinted loci, samples with skewed X-inactivation patterns, and novel differentially methylated regions. All raw sequencing data, processed data, and summary statistics are publicly available, providing a valuable resource for the clinical genetics community to discover pathogenic SVs.

Long-Read DNA and RNA Sequencing to Streamline Clinical Genetic Testing and Reduce Barriers to Comprehensive Genetic Testing.

BACKGROUND: Obtaining a precise molecular diagnosis through clinical genetic testing provides information about disease prognosis or progression, allows accurate counseling about recurrence risk, and empowers individuals to benefit from precision therapies or take part in N-of-1 trials. Unfortunately, more than half of individuals with a suspected Mendelian condition remain undiagnosed after a comprehensive clinical evaluation, and the results of any individual clinical genetic test ordered during a typical evaluation may take weeks or months to return. Furthermore, commonly used technologies, such as short-read sequencing, are limited in the types of disease-causing variation they can identify. New technologies, such as long-read sequencing (LRS), are poised to solve these problems. CONTENT: Recent technical advances have improved accuracy, increased throughput, and decreased the costs of commercially available LRS technologies. This has resolved many historical concerns about the use of LRS in the clinical environment and opened the door to widespread clinical adoption of LRS. Here, we review LRS technology, how it has been used in the research setting to clarify complex variants or identify disease-causing variation missed by prior clinical testing, and how it may be used clinically in the near future. SUMMARY: LRS is unique in that, as a single data source, it has the potential to replace nearly every other clinical genetic test offered today. When analyzed in a stepwise fashion, LRS will simplify laboratory processes, reduce barriers to comprehensive genetic testing, increase the rate of genetic diagnoses, and shorten the amount of time required to make a molecular diagnosis.

Beyond coping: The role of supportive relationships and meaning making in youth well-being.

INTRODUCTION: The purpose of this study was to identify coping strategies, resources, and strengths that predict well-being in a community-based sample of youth with varying levels of adversity. DESIGN: Grounded in the resilience portfolio model, we used a mixed methods approach with data from a cross-sectional sample of 231 youth ages 8-17. MATERIALS AND METHODS: Data were collected using a survey, participant-generated timeline activity, and brief interview. Measures included assessments of coping and appraisal, resilience resources and assets, and subjective well-being and depression. RESULTS: Active and passive coping strategies predicted subjective well-being and depression. Controlling for demographics and coping, meaning making strengths and supportive relationships were significant predictors of subjective well-being and lower depression, and decreased the impact of adversity on these outcomes. DISCUSSION: The results of this study provide support for the resilience portfolio model in a community-based sample of youth, with relationships as predicted for subjective well-being and symptoms of depression. For both outcomes, family relationships held the strongest associations with positive well-being and lower symptoms of depression. Supportive relationships with peers, meaning making strengths, interpersonal strengths, less passive coping, and fewer adverse life events were also associated with better outcomes. CONCLUSIONS: These findings underscore the need to assess youth resources and strengths and to design interventions that target these protective factors for all youth, regardless of exposure to adversity. CLINICAL RELEVANCE: A theory-informed understanding of resources and strengths that predict youth well-being is essential to inform strengths-based interventions for pediatric research and practice. The resilience portfolio model is a useful framework for understanding predictors of youth well-being.

Assessment of Youth Coping and Appraisals Through a Timelining Activity: Validation and Utility of a Tool for Pediatric Research and Practice.

INTRODUCTION: Many tools to assess coping in youth fail to engage youth meaningfully in the assessment process. This study aimed to evaluate a brief timeline activity as an interactive way to assess appraisal and coping in pediatric research and practice. METHOD: We used a mixed method convergent design to collect and analyze survey and interview data from 231 youths aged 8-17 years in a community-based setting. RESULTS: The youth engaged readily in the timeline activity and found the activity easy to understand. Relationships among appraisal, coping, subjective well-being and depression were in the hypothesized directions, suggesting the tool supports a valid assessment of appraisals and coping in this age group. DISCUSSION: The timelining activity is well-accepted by youth and supports reflexivity, prompting youth to share insights on strengths and resilience. The tool may augment existing practices for assessing and intervening in youth mental health in research and practice.

Female Meiosis: Synapsis, Recombination, and Segregation in Drosophila melanogaster.

A century of genetic studies of the meiotic process in Drosophila melanogaster females has been greatly augmented by both modern molecular biology and major advances in cytology. These approaches, and the findings they have allowed, are the subject of this review. Specifically, these efforts have revealed that meiotic pairing in Drosophila females is not an extension of somatic pairing, but rather occurs by a poorly understood process during premeiotic mitoses. This process of meiotic pairing requires the function of several components of the synaptonemal complex (SC). When fully assembled, the SC also plays a critical role in maintaining homolog synapsis and in facilitating the maturation of double-strand breaks (DSBs) into mature crossover (CO) events. Considerable progress has been made in elucidating not only the structure, function, and assembly of the SC, but also the proteins that facilitate the formation and repair of DSBs into both COs and noncrossovers (NCOs). The events that control the decision to mature a DSB as either a CO or an NCO, as well as determining which of the two CO pathways (class I or class II) might be employed, are also being characterized by genetic and genomic approaches. These advances allow a reconsideration of meiotic phenomena such as interference and the centromere effect, which were previously described only by genetic studies. In delineating the mechanisms by which the oocyte controls the number and position of COs, it becomes possible to understand the role of CO position in ensuring the proper orientation of homologs on the first meiotic spindle. Studies of bivalent orientation have occurred in the context of numerous investigations into the assembly, structure, and function of the first meiotic spindle. Additionally, studies have examined the mechanisms ensuring the segregation of chromosomes that have failed to undergo crossing over.

The Molecular and Genetic Characterization of Second Chromosome Balancers in Drosophila melanogaster.

Balancer chromosomes are multiply inverted and rearranged chromosomes used in Drosophila melanogaster for many tasks, such as maintaining mutant alleles in stock and complex stock construction. Balancers were created before molecular characterization of their breakpoints was possible, so the precise locations of many of these breakpoints are unknown. Here, we report or confirm the positions of the 14 euchromatic breakpoints on the 2nd chromosome balancers SM1, SM5, CyO, and SM6a This total includes three breakpoints involved in a complex rearrangement on SM5 that is associated with the duplication of two genomic regions. Unbiased sequencing of several balancers allowed us to identify stocks with incorrectly identified balancers as well as single and double crossover events that had occurred between 2nd chromosome balancers and their homologs. The confirmed crossover events that we recovered were at least 2 Mb from the closest inversion breakpoint, consistent with observations from other balancer chromosomes. Balancer chromosomes differ from one another both by large tracts of sequence diversity generated by recombination and by small differences, such as single nucleotide polymorphisms (SNPs). Therefore, we also report loss-of-function mutations carried by these chromosomes and unique SNP and InDel polymorphisms present on only single balancers. These findings provide valuable information about the structure of commonly used 2nd chromosome balancers and extend recent work examining the structure of X and 3rd chromosome balancers. Finally, these observations provide new insights into how the sequences of individual balancers have diverged over time.