scholarly journals A combined RNA-seq and whole genome sequencing approach for identification of non-coding pathogenic variants in single families

2019 ◽  
Author(s):  
Revital Bronstein ◽  
Elizabeth E. Capowski ◽  
Sudeep Mehrotra ◽  
Alex D. Jansen ◽  
Daniel Navarro-Gomez ◽  
...  

AbstractInherited retinal degenerations (IRDs) are at the focus of current genetic therapeutic advancements. For a genetic treatment such as gene therapy to be successful an accurate genetic diagnostic is required. Genetic diagnostics relies on the assessment of the probability that a given DNA variant is pathogenic. Non-coding variants present a unique challenge for such assessments as compared to coding variants. For one, non-coding variants are present at much higher number in the genome than coding variants. In addition, our understanding of the rules that govern the non-coding regions of the genome is less complete than our understanding of the coding regions. Methods that allow for both the identification of candidate non-coding pathogenic variants and their functional validation may help overcome these caveats allowing for a greater number of patients to benefit from advancements in genetic therapeutics. We present here an unbiased approach combining whole genome sequencing (WGS) with patient induced pluripotent stem cell (iPSC) derived retinal organoids (ROs) transcriptome analysis. With this approach we identified and functionally validated a novel pathogenic non-coding variant in a small family with a previously unresolved genetic diagnosis.

2020 ◽  
Vol 29 (6) ◽  
pp. 967-979 ◽  
Author(s):  
Revital Bronstein ◽  
Elizabeth E Capowski ◽  
Sudeep Mehrotra ◽  
Alex D Jansen ◽  
Daniel Navarro-Gomez ◽  
...  

Abstract Inherited retinal degenerations (IRDs) are at the focus of current genetic therapeutic advancements. For a genetic treatment such as gene therapy to be successful, an accurate genetic diagnostic is required. Genetic diagnostics relies on the assessment of the probability that a given DNA variant is pathogenic. Non-coding variants present a unique challenge for such assessments as compared to coding variants. For one, non-coding variants are present at much higher number in the genome than coding variants. In addition, our understanding of the rules that govern the non-coding regions of the genome is less complete than our understanding of the coding regions. Methods that allow for both the identification of candidate non-coding pathogenic variants and their functional validation may help overcome these caveats allowing for a greater number of patients to benefit from advancements in genetic therapeutics. We present here an unbiased approach combining whole genome sequencing (WGS) with patient-induced pluripotent stem cell (iPSC)-derived retinal organoids (ROs) transcriptome analysis. With this approach, we identified and functionally validated a novel pathogenic non-coding variant in a small family with a previously unresolved genetic diagnosis.


2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Zeinab Fadaie ◽  
Laura Whelan ◽  
Tamar Ben-Yosef ◽  
Adrian Dockery ◽  
Zelia Corradi ◽  
...  

AbstractInherited retinal diseases (IRDs) are a major cause of visual impairment. These clinically heterogeneous disorders are caused by pathogenic variants in more than 270 genes. As 30–40% of cases remain genetically unexplained following conventional genetic testing, we aimed to obtain a genetic diagnosis in an IRD cohort in which the genetic cause was not found using whole-exome sequencing or targeted capture sequencing. We performed whole-genome sequencing (WGS) to identify causative variants in 100 unresolved cases. After initial prioritization, we performed an in-depth interrogation of all noncoding and structural variants in genes when one candidate variant was detected. In addition, functional analysis of putative splice-altering variants was performed using in vitro splice assays. We identified the genetic cause of the disease in 24 patients. Causative coding variants were observed in genes such as ATXN7, CEP78, EYS, FAM161A, and HGSNAT. Gene disrupting structural variants were also detected in ATXN7, PRPF31, and RPGRIP1. In 14 monoallelic cases, we prioritized candidate noncanonical splice sites or deep-intronic variants that were predicted to disrupt the splicing process based on in silico analyses. Of these, seven cases were resolved as they carried pathogenic splice defects. WGS is a powerful tool to identify causative variants residing outside coding regions or heterozygous structural variants. This approach was most efficient in cases with a distinct clinical diagnosis. In addition, in vitro splice assays provide important evidence of the pathogenicity of rare variants.


BMJ ◽  
2021 ◽  
pp. e066288 ◽  
Author(s):  
Katherine R Schon ◽  
Rita Horvath ◽  
Wei Wei ◽  
Claudia Calabrese ◽  
Arianna Tucci ◽  
...  

Abstract Objective To determine whether whole genome sequencing can be used to define the molecular basis of suspected mitochondrial disease. Design Cohort study. Setting National Health Service, England, including secondary and tertiary care. Participants 345 patients with suspected mitochondrial disorders recruited to the 100 000 Genomes Project in England between 2015 and 2018. Intervention Short read whole genome sequencing was performed. Nuclear variants were prioritised on the basis of gene panels chosen according to phenotypes, ClinVar pathogenic/likely pathogenic variants, and the top 10 prioritised variants from Exomiser. Mitochondrial DNA variants were called using an in-house pipeline and compared with a list of pathogenic variants. Copy number variants and short tandem repeats for 13 neurological disorders were also analysed. American College of Medical Genetics guidelines were followed for classification of variants. Main outcome measure Definite or probable genetic diagnosis. Results A definite or probable genetic diagnosis was identified in 98/319 (31%) families, with an additional 6 (2%) possible diagnoses. Fourteen of the diagnoses (4% of the 319 families) explained only part of the clinical features. A total of 95 different genes were implicated. Of 104 families given a diagnosis, 39 (38%) had a mitochondrial diagnosis and 65 (63%) had a non-mitochondrial diagnosis. Conclusion Whole genome sequencing is a useful diagnostic test in patients with suspected mitochondrial disorders, yielding a diagnosis in a further 31% after exclusion of common causes. Most diagnoses were non-mitochondrial disorders and included developmental disorders with intellectual disability, epileptic encephalopathies, other metabolic disorders, cardiomyopathies, and leukodystrophies. These would have been missed if a targeted approach was taken, and some have specific treatments.


2018 ◽  
Author(s):  
Ann-Charlotte Thuresson ◽  
Cecilia Soussi Zander ◽  
Jin J. Zhao ◽  
Jonatan Halvardson ◽  
Khurram Maqbool ◽  
...  

2020 ◽  
Vol 6 (3) ◽  
pp. a003970
Author(s):  
Isabelle Thiffault ◽  
Andrea Atherton ◽  
Bryce A. Heese ◽  
Ahmed T. Abdelmoity ◽  
Kailash Pawar ◽  
...  

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e13113-e13113
Author(s):  
Howard John Lim ◽  
Kasmintan A Schrader ◽  
Sean Young ◽  
Jessica Nelson ◽  
Alexandra Fok ◽  
...  

e13113 Background: The Personalized OncoGenomics (POG) project at the BC Cancer Agency utilizes tumor-normal whole genome sequencing (WGS) to understand key driver pathways and guide personalized treatment decisions. Analysis of the germline data can reveal variants; these may be presumed pathogenic, presumed benign or of unknown significance (VUS). We have developed a process for evaluating and returning presumed pathogenic variants in known cancer susceptibility genes to patients, for counseling and validation in a clinical-accredited laboratory. Methods: Patients receive germline cancer related information as part of the consent process for participation in the POG program. A sub-committee comprised of medical geneticists, bioinformaticians, pathologists, oncologists and an ethicist review the germline results. Any variants suspicious of being an artifact undergo a technical validation step. Presumed pathogenic findings of known cancer susceptibility genes are returned to the patient by their treating oncologist and patients are referred to the Hereditary Cancer Program (HCP), for genetic counseling and clinical confirmation. Results: From June 2012 - January 2017 – 466 patients have consented to the project. To date, 39 cases (8.4%) had at least one variant that was deemed pathogenic, 86 cases had at least one VUS in a known cancer susceptibility gene. 11 out of 23 cases (47.8%) with high penetrance mutations were already known to HCP. All VUS were reviewed by the sub-committee taking in to consideration the VUS and clinical context. 8 of the subjects with pathogenic results and 3 with VUS were known to HCP before POG data was generated. A VUS in 7 cases (1.5%) was returned after review. Conclusions: The number of pathogenic variants in known cancer susceptibility genes is consistent with published oncology results. We created a process to manage clinically relevant germline findings discovered during the course of genomic research to ensure appropriate care for patients. Genetic counseling within HCP and validation of variants in the clinically accredited Cancer Genetics Laboratory enables seamless return of research generated clinically relevant germline results to affected subjects. Clinical trial information: NCT02155621.


2021 ◽  
Author(s):  
Jeroen Smits ◽  
Suzanne E. de Bruijn ◽  
Cornelis P. Lanting ◽  
Jaap Oostrik ◽  
Luke O’Gorman ◽  
...  

Abstract Pathogenic variants in SLC26A4 have been associated with autosomal recessive hearing loss (arHL) and a unilateral or bilateral enlarged vestibular aqueduct (EVA). SLC26A4 is the second most frequently mutated gene in arHL. Despite the strong genotype-phenotype correlation, a significant part of SLC26A4 cases remains genetically unresolved. In this study, we investigated a cohort of 28 Dutch index cases diagnosed with HL in combination with an EVA but without (M0) or with a single (M1) pathogenic variant in SLC26A4. To explore the missing heritability, short- and long-read whole genome sequencing and optical genome mapping were performed. We found a previously described EVA-associated haplotype (Caucasian EVA (CEVA)) to be significantly enriched in our M1 patient cohort. The haplotype was also present in two M0 cases. Despite extensive genetic analyses, we were not able to prioritize any of the variants present within the haplotype as the likely pathogenic defect, and therefore additional analyses addressing the defect(s) at the RNA, protein, or epigenetic level are required. Whole genome sequencing also revealed splice-altering SLC26A4 variants in two M1 cases, which are now genetically explained, but no deep-intronic or copy number variants. With these findings, we have provided important insights that will pave the way for elucidating the missing heritability in M0 and M1 SLC26A4 cases.


2020 ◽  
Author(s):  
Bernard J. Pope ◽  
Mark Clendenning ◽  
Christophe Rosty ◽  
Khalid Mahmood ◽  
Peter Georgeson ◽  
...  

AbstractBackgroundPeople who develop mismatch repair (MMR) deficient cancer in the absence of a germline MMR gene pathogenic variant or hypermethylation of the MLH1 gene promoter in their tumor are classified as having suspected Lynch syndrome (SLS). We applied germline whole genome sequencing (WGS) and targeted and genome-wide tumor sequencing approaches to identify the underlying cause of tumor MMR-deficiency in SLS.MethodsGermline WGS was performed on 14 cancer-affected people with SLS, including two sets of first-degree relatives. Tumor tissue was sequenced for somatic MMR gene mutations by targeted, whole exome sequencing or WGS. Germline pathogenic variants, including complex structural rearrangements and non-coding variants, were assessed for the MMR genes. Tumor mutation burden and mutational signatures.ResultsGermline WGS identified pathogenic MMR variants in 3 of the 14 (21.4%) SLS cases including a 9.5Mb inversion disrupting exons 1-7 of MSH2 in a mother and daughter. Excluding these 3 MMR carriers, tumor sequencing identified at least two somatic MMR gene mutations in 8/11 (72.7%) tumors tested, supporting a non-inherited cause of tumor MMR-deficiency. In the second mother-daughter pair, the combined analysis of germline and tumor by WGS supported a somatic rather than inherited cause of their tumor MMR-deficiency, through presence of double somatic MSH2 mutations in their respective tumors.ConclusionGermline WGS of people with SLS improved the identification of Lynch syndrome. When coupled with tumor sequencing, >70% of the people with SLS were resolved as having double somatic MMR mutations and a non-inherited cause for their tumor MMR-deficiency.


2017 ◽  
Author(s):  
Josh E. Petrikin ◽  
Julie A. Cakici ◽  
Michelle M. Clark ◽  
Laurel K. Willig ◽  
Nathaly M. Sweeney ◽  
...  

AbstractImportanceGenetic disorders, including congenital anomalies, are a leading cause of morbidity and mortality in infants, especially in neonatal and pediatric intensive care units (NICU and PICU). While genomic sequencing is useful for diagnosis of genetic diseases, results are usually reported too late to guide inpatient management.ObjectiveTo test the hypothesis that rapid whole genome sequencing (rWGS) increases the proportion of infants in NICUs and PICUs receiving a genetic diagnosis within 28 days.DesignAn investigator-initiated, partially blinded, pragmatic, randomized controlled study with enrollment from October 2014 - June 2016, and follow up until December 2016.SettingA regional neonatal and pediatric intensive care unit in a tertiary referral childrens hospital.ParticipantsSixty five of 129 screened families with infants aged less than four months, in neonatal and pediatric intensive care units, and with illnesses of unknown etiology, completed the study.InterventionParent and infant trio rWGS.Main Outcome and MeasureThe hypothesis and end-points were formulated a priori. The primary end-point was rate of genetic diagnosis within 28 days of enrollment or first standard test order.ResultsTwenty six female proband infants, 37 male infants, and two infants of undetermined sex were randomized to receive rWGS plus standard tests (n=32, cases) or standard tests alone (n=33, controls). The study was terminated early due to loss of equipoise: 63% (21) controls received genomic sequencing as standard tests. Nevertheless, intention to treat analysis showed the rate of genetic diagnosis within 28 days to be higher in cases (31%, ten of 32) than controls (3%, one of 33; difference, 28% [95% CI, 10% to 46%]; p=0.003). Among infants enrolled in the first 25 days of life, the rate of neonatal diagnosis was higher in cases (32%, seven of 22) than controls (0%, zero of 23; difference, 32% [95% CI, 11% to 53%]; p=0.004). Age at diagnosis (median in cases 25 days, range 14-90 days vs median in controls 130 days, range 37-451) and time to diagnosis (median in cases thirteen days, range 1-84 days vs median in controls 107 days, range 21-429 days) were significantly less in cases than controls (p=0.04).CONCLUSIONSrWGS increased the proportion of infants in a regional NICU and PICU who received a timely diagnosis of a genetic disease. Additional, adequately powered studies are needed to determine whether accelerated diagnosis is associated with improved outcomes in this setting. ClinicalTrials.gov Identifier: NCT02225522.


2021 ◽  
Author(s):  
Malgorzata Borczyk ◽  
Jakup P Fichna ◽  
Marcin Piechota ◽  
Sławomir Gołda ◽  
Michał Korostyński ◽  
...  

Gilles de la Tourette syndrome (GTS) is a neurodevelopmental disorder from the spectrum of tic disorders (TDs). GTS and other TDs have a substantial genetic component with the heritability estimated at between 60 and 80%. Here we propose an oligogenic risk model of GTS and other TDs using whole-genome sequencing (WGS) data from a group of Polish GTS patients and their families (n=185). The model is based on the overrepresentation of putatively pathogenic coding and non-coding genetic variants in genes selected from a set of 86 genes previously suggested to be associated with GTS. Based on the variant overrepresentation (SKAT test results) between unrelated GTS patients and controls based on gnomAD database allele frequencies five genes (HDC, CHADL, MAOA, NAA11, and PCDH10) were selected for the risk model. Putatively pathogenic variants (n = 98) with the median allele frequency of ~0.04 in and near these genes were used to build an additive classifier which was then validated on the GTS patients and their families. This risk model successfully assigned individuals from 22 families to either healthy or GTS groups (AUC-ROC = 0.6, p < 0.00001). These results were additionally validated using the GTS GWAS data from the Psychiatric Genomic Consortium. To investigate the GTS genetics further we identified 32 genes from the list of 86 genes as candidate genes in 14 multiplex families, including NEGR1 and NRXN with variants overrepresented in multiple families. WGS data allowed the construction of an oligogenic risk model of GTS based on possibly pathogenic variants likely contributing to the risk of GTS and TDs. The model includes putatively deleterious rare and non-coding variants in and near GTS candidate genes that may cooperatively contribute to GTS etiology and provides a novel approach to the analysis of clinical WGS data.


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