Translating whole-exome sequencing (WES) for prospective clinical use may have an impact on the care of patients with cancer; however, multiple innovations are necessary for clinical implementation. ...These include rapid and robust WES of DNA derived from formalin-fixed, paraffin-embedded tumor tissue, analytical output similar to data from frozen samples and clinical interpretation of WES data for prospective use. Here, we describe a prospective clinical WES platform for archival formalin-fixed, paraffin-embedded tumor samples. The platform employs computational methods for effective clinical analysis and interpretation of WES data. When applied retrospectively to 511 exomes, the interpretative framework revealed a 'long tail' of somatic alterations in clinically important genes. Prospective application of this approach identified clinically relevant alterations in 15 out of 16 patients. In one patient, previously undetected findings guided clinical trial enrollment, leading to an objective clinical response. Overall, this methodology may inform the widespread implementation of precision cancer medicine.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
As researchers begin probing deep coverage sequencing data for increasingly rare mutations and subclonal events, the fidelity of next generation sequencing (NGS) laboratory methods will become ...increasingly critical. Although error rates for sequencing and polymerase chain reaction (PCR) are well documented, the effects that DNA extraction and other library preparation steps could have on downstream sequence integrity have not been thoroughly evaluated. Here, we describe the discovery of novel C > A/G > T transversion artifacts found at low allelic fractions in targeted capture data. Characteristics such as sequencer read orientation and presence in both tumor and normal samples strongly indicated a non-biological mechanism. We identified the source as oxidation of DNA during acoustic shearing in samples containing reactive contaminants from the extraction process. We show generation of 8-oxoguanine (8-oxoG) lesions during DNA shearing, present analysis tools to detect oxidation in sequencing data and suggest methods to reduce DNA oxidation through the introduction of antioxidants. Further, informatics methods are presented to confidently filter these artifacts from sequencing data sets. Though only seen in a low percentage of reads in affected samples, such artifacts could have profoundly deleterious effects on the ability to confidently call rare mutations, and eliminating other possible sources of artifacts should become a priority for the research community.
Structural variation (SV) influences genome organization and contributes to human disease. However, the complete mutational spectrum of SV has not been routinely captured in disease association ...studies.
We sequenced 689 participants with autism spectrum disorder (ASD) and other developmental abnormalities to construct a genome-wide map of large SV. Using long-insert jumping libraries at 105X mean physical coverage and linked-read whole-genome sequencing from 10X Genomics, we document seven major SV classes at ~5 kb SV resolution. Our results encompass 11,735 distinct large SV sites, 38.1% of which are novel and 16.8% of which are balanced or complex. We characterize 16 recurrent subclasses of complex SV (cxSV), revealing that: (1) cxSV are larger and rarer than canonical SV; (2) each genome harbors 14 large cxSV on average; (3) 84.4% of large cxSVs involve inversion; and (4) most large cxSV (93.8%) have not been delineated in previous studies. Rare SVs are more likely to disrupt coding and regulatory non-coding loci, particularly when truncating constrained and disease-associated genes. We also identify multiple cases of catastrophic chromosomal rearrangements known as chromoanagenesis, including somatic chromoanasynthesis, and extreme balanced germline chromothripsis events involving up to 65 breakpoints and 60.6 Mb across four chromosomes, further defining rare categories of extreme cxSV.
These data provide a foundational map of large SV in the morbid human genome and demonstrate a previously underappreciated abundance and diversity of cxSV that should be considered in genomic studies of human disease.
Treatment of BRAF-mutant melanoma with combined dabrafenib and trametinib, which target RAF and the downstream MAP-ERK kinase (MEK)1 and MEK2 kinases, respectively, improves progression-free survival ...and response rates compared with dabrafenib monotherapy. Mechanisms of clinical resistance to combined RAF/MEK inhibition are unknown. We performed whole-exome sequencing (WES) and whole-transcriptome sequencing (RNA-seq) on pretreatment and drug-resistant tumors from five patients with acquired resistance to dabrafenib/trametinib. In three of these patients, we identified additional mitogen-activated protein kinase (MAPK) pathway alterations in the resistant tumor that were not detected in the pretreatment tumor, including a novel activating mutation in MEK2 (MEK2(Q60P)). MEK2(Q60P) conferred resistance to combined RAF/MEK inhibition in vitro, but remained sensitive to inhibition of the downstream kinase extracellular signal-regulated kinase (ERK). The continued MAPK signaling-based resistance identified in these patients suggests that alternative dosing of current agents, more potent RAF/MEK inhibitors, and/or inhibition of the downstream kinase ERK may be needed for durable control of BRAF-mutant melanoma.
Although genetic lesions responsible for some mendelian disorders can be rapidly discovered through massively parallel sequencing of whole genomes or exomes, not all diseases readily yield to such ...efforts. We describe the illustrative case of the simple mendelian disorder medullary cystic kidney disease type 1 (MCKD1), mapped more than a decade ago to a 2-Mb region on chromosome 1. Ultimately, only by cloning, capillary sequencing and de novo assembly did we find that each of six families with MCKD1 harbors an equivalent but apparently independently arising mutation in sequence markedly under-represented in massively parallel sequencing data: the insertion of a single cytosine in one copy (but a different copy in each family) of the repeat unit comprising the extremely long (∼1.5-5 kb), GC-rich (>80%) coding variable-number tandem repeat (VNTR) sequence in the MUC1 gene encoding mucin 1. These results provide a cautionary tale about the challenges in identifying the genes responsible for mendelian, let alone more complex, disorders through massively parallel sequencing.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
We present an automated, high throughput library construction process for 454 technology. Sample handling errors and cross-contamination are minimized via end-to-end barcoding of plasticware, along ...with molecular DNA barcoding of constructs. Automation-friendly magnetic bead-based size selection and cleanup steps have been devised, eliminating major bottlenecks and significant sources of error. Using this methodology, one technician can create 96 sequence-ready 454 libraries in 2 days, a dramatic improvement over the standard method.
Abstract
INTRODUCTION: Knowledge of tumor genomic alterations that may predict therapeutic responses represents a growing clinical need. Although there has been an increase in the use of hotspot ...genotyping and targeted sequencing panels of small numbers of genes, the use of clinical whole exome sequencing (WES) remains underdeveloped. Prospective WES in cancer patients presents several logistical and scientific challenges, including (i) generating robust sequencing data from small amounts of FFPE tumor tissue, (ii) establishing a clinically relevant turnaround time, (iii) achieving clinical interpretation of genomic alterations, and (iv) communicating results to the clinical team and patients. Here, we describe CanSeq, a clinical WES platform to detect genomic alterations in FFPE tumor samples and identify clinically actionable and biologically meaningful alterations in order to aid clinical decision-making and inform future research.
METHODS: We performed prospective WES on tumor and germline DNA from patients with advanced refractory cancer. Sequencing was performed at the Broad Institute using the Illumina HiSeq, starting with 100 ng of DNA or less from FFPE tumor tissue and matched normal blood. Data were analyzed using a novel algorithm to highlight clinically actionable mutations, indels, and copy number alterations. These were annotated and assigned levels of evidence, and an interactive web-based report was generated for review by clinicians.
RESULTS: The average turnaround time from sample receipt to data delivery was 16 days. Each tumor sample was sequenced at 90X or greater depth of coverage with more than 80% of exons with at least 30X coverage. Analysis of the first 15 patients revealed at least one plausibly actionable somatic mutation in 14 samples. These alterations include “standard of care” alterations (BRAF, EGFR), entry criteria for clinical trials (PIK3CA, KRAS, PTEN), potentially actionable alterations based on more limited evidence (STK11, ATM, CRKL, CTNNB1, PDGFRA, CDK4, CDKN2A, SMARCB1, TP53), and alterations that were theoretically targetable (JAK3, SYK). Additional biologically relevant somatic alterations and notable germline alterations were also identified. For several patients, actionable alterations were confirmed in a CLIA lab and impacted clinical decision-making, including enrollment in clinical trials.
CONCLUSION: We have developed a prospective clinical WES platform to robustly detect genomic alterations in archival FFPE tumor samples (using <100 ng DNA) in a clinically appropriate time frame (<3 wks). The platform enables rapid identification of clinically relevant information from vast numbers of somatic and germline events. The ability to use real world biopsy samples could facilitate the routine incorporation of WES into the care of cancer patients, speeding the advent of precision cancer medicine by identifying the actionable genetic changes in each patient's tumor.
Citation Format: Nikhil Wagle, Eliezer Van Allen, Danielle Perrin, Dennis Friedrich, Sheila Fisher, Gregory Kryukov, Lauren Ambrogio, Daniel Auclair, Stacy Gray, Steven Joffe, Pasi Janne, Judy Garber, Laura Macconaill, Neal Lindeman, Barrett Rollins, Phillip Kantoff, Gad Getz, Stacey Gabriel, Levi A. Garraway. CanSeq: prospective clinical whole-exome sequencing of FFPE tumor samples. abstract. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3152. doi:10.1158/1538-7445.AM2013-3152
Translating whole exome sequencing (WES) for prospective clinical use may impact the care of cancer patients; however, multiple innovations are necessary for clinical implementation. These include: ...(1) rapid and robust WES from formalin-fixed paraffin embedded (FFPE) tumor tissue, (2) analytical output similar to data from frozen samples, and (3) clinical interpretation of WES data for prospective use. Here, we describe a prospective clinical WES platform for archival FFPE tumor samples. The platform employs computational methods for effective clinical analysis and interpretation of WES data. When applied retrospectively to 511 exomes, the interpretative framework revealed a “long tail” of somatic alterations in clinically important genes. Prospective application of this approach identified clinically relevant alterations in 15/16 patients. In one patient, previously undetected findings guided clinical trial enrollment leading to an objective clinical response. Overall, this methodology may inform the widespread implementation of precision cancer medicine.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Changes to farm production subsidies are provoking the maintenance of far less stock. Given that wildlife is more abundant in sustainable uplands, pathogens able to exploit both wild-living and ...domesticated hosts are of particular concern. Tick-borne pathogens are not only a case in point; but also their threat is now augmented by increasing tick abundance, changing climate, and the extraordinary nationwide increase in the abundance of deer (that serve as a key host species).The major objective of this thesis was to further understand the spatial distribution of questing Ixodes ricinus ticks across farms in Southern Cumbria; as well as to attempt to understand the epidemiological and ecological factors that have a significant influence on the patterns of infections in livestock. This project integrated field work, GIS, molecular methods and citizen science in an effort to understand these complex epidemiologies.Results demonstrated that: I. ricinus exhibit a patchy distribution across all study sites, with proximity to woodland indicated as the main driver behind this. The causal agent of tick borne fever, Anaplasma phagocytophilum was observed across the sites, with sheep being implicated as the main drivers behind this, rather than deer.Conflicting to anecdotal evidence, Babesia divergens (the agent of red water fever in cattle) was not found at any of the sites. However, the discovery of B. venatorum in a new area of the UK is of potential medical importance. In addition to the confirmation of B. OO-2012, and a B. odocoilei- like species; this, to the best of my knowledge, is the first recording of these pathogens in the UK.Contrary to scientific studies, Borrelia afzelli was observed in adult I ricinus females feeding on cattle; suggesting that the results from in vitro assays do not seamlessly translate into the field, and that further work is needed to quantify the role cattle may play in the circulation of Borrelia, which is of public health importance. Louping Ill Virus was sampled for, but was not confirmed.The truly multidisciplinary nature of this project, has demonstrated the need for a holistic approach when considering the ecology and epidemiology of tick borne disease
Introduction
The Alzheimer's Disease Neuroimaging Initiative (ADNI) has accumulated 15 years of clinical, neuroimaging, cognitive, biofluid biomarker and genetic data, and biofluid samples available ...to researchers, resulting in more than 3500 publications. This review covers studies from 2018 to 2020.
Methods
We identified 1442 publications using ADNI data by conventional search methods and selected impactful studies for inclusion.
Results
Disease progression studies supported pivotal roles for regional amyloid beta (Aβ) and tau deposition, and identified underlying genetic contributions to Alzheimer's disease (AD). Vascular disease, immune response, inflammation, resilience, and sex modulated disease course. Biologically coherent subgroups were identified at all clinical stages. Practical algorithms and methodological changes improved determination of Aβ status. Plasma Aβ, phosphorylated tau181, and neurofilament light were promising noninvasive biomarkers. Prognostic and diagnostic models were externally validated in ADNI but studies are limited by lack of ethnocultural cohort diversity.
Discussion
ADNI has had a profound impact in improving clinical trials for AD.
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