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Open accessJournal ArticleDOI: 10.3389/FGENE.2021.647400

Identification of Deep-Intronic Splice Mutations in a Large Cohort of Patients With Inherited Retinal Diseases.

02 Mar 2021-Frontiers in Genetics (Frontiers Media S. A.)-Vol. 12, pp 647400-647400
Abstract: High throughput sequencing technologies have revolutionized the identification of mutations responsible for a diverse set of Mendelian disorders, including inherited retinal disorders (IRDs). However, the causal mutations remain elusive for a significant proportion of patients. This may be partially due to pathogenic mutations located in non-coding regions, which are largely missed by capture sequencing targeting the coding regions. The advent of whole-genome sequencing (WGS) allows us to systematically detect non-coding variations. However, the interpretation of these variations remains a significant bottleneck. In this study, we investigated the contribution of deep-intronic splice variants to IRDs. WGS was performed for a cohort of 571 IRD patients who lack a confident molecular diagnosis, and potential deep intronic variants that affect proper splicing were identified using SpliceAI. A total of six deleterious deep intronic variants were identified in eight patients. An in vitro minigene system was applied to further validate the effect of these variants on the splicing pattern of the associated genes. The prediction scores assigned to splice-site disruption positively correlated with the impact of mutations on splicing, as those with lower prediction scores demonstrated partial splicing. Through this study, we estimated the contribution of deep-intronic splice mutations to unassigned IRD patients and leveraged in silico and in vitro methods to establish a framework for prioritizing deep intronic variant candidates for mechanistic and functional analyses.

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Topics: Minigene (52%)

5 results found

Open accessJournal ArticleDOI: 10.3390/GENES12091308
Changhee Ha1, Jong-Won Kim1, Ja-Hyun Jang1Institutions (1)
25 Aug 2021-Genes
Abstract: Neurofibromatosis type 1, characterized by neurofibromas and cafe-au-lait macules, is one of the most common genetic disorders caused by pathogenic NF1 variants. Because of the high proportion of splicing mutations in NF1, identifying variants that alter splicing may be an essential issue for laboratories. Here, we investigated the sensitivity and specificity of SpliceAI, a recently introduced in silico splicing prediction algorithm in conjunction with other in silico tools. We evaluated 285 NF1 variants identified from 653 patients. The effect on variants on splicing alteration was confirmed by complementary DNA sequencing followed by genomic DNA sequencing. For in silico prediction of splicing effects, we used SpliceAI, MaxEntScan (MES), and Splice Site Finder-like (SSF). The sensitivity and specificity of SpliceAI were 94.5% and 94.3%, respectively, with a cut-off value of Δ Score > 0.22. The area under the curve of SpliceAI was 0.975 (p < 0.0001). Combined analysis of MES/SSF showed a sensitivity of 83.6% and specificity of 82.5%. The concordance rate between SpliceAI and MES/SSF was 84.2%. SpliceAI showed better performance for the prediction of splicing alteration for NF1 variants compared with MES/SSF. As a convenient web-based tool, SpliceAI may be helpful in clinical laboratories conducting DNA-based NF1 sequencing.

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Topics: RNA splicing (54%), In silico (51%)

Open accessPosted ContentDOI: 10.1101/2021.07.23.21261017
Eva Lenassi1, Eva Lenassi2, Eva Lenassi3, Ana Carvalho4  +18 moreInstitutions (6)
25 Jul 2021-medRxiv
Abstract: PurposeThe widespread adoption of genomic testing for individuals with ophthalmic disorders has increased demand on diagnostic genomic services for these conditions. Moreover, the clinical utility of a molecular diagnosis for individuals with inherited ophthalmic disorders is increasingly placing pressure on the speed and accuracy of genomic testing. MethodsWe created EyeG2P, a publically available resource to assist diagnostic filtering of genomic datasets for ophthalmic conditions, utilising the Ensembl Variant Effect Predictor. We assessed the sensitivity of EyeG2P for 1234 individuals with a broad range of conditions, who had previously received a confirmed molecular diagnosis through routine genomic diagnostic approaches. For a prospective cohort of 83 individuals, we also assessed the precision of EyeG2P in comparision to routine genomic diagnostic approaches. ResultsWe observed that EyeG2P had a 99.5% sensitivity for genomic variants previously identified as a molecular diagnosis for 1234 individuals. EyeG2P enabled a significant increase in precision in comparison to routine testing strategies (p<0.001), with an increased precision in variant analysis of 35% per individual, on average. ConclusionAutomated filtering of genomic variants through EyeG2P can increase the efficiency of diagnostic testing for individuals with a broad range of inherited ophthalmic disorders.

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Open accessJournal ArticleDOI: 10.3390/CANCERS13133341
03 Jul 2021-Cancers
Abstract: The contribution of deep intronic splice-altering variants to hereditary breast and ovarian cancer (HBOC) is unknown. Current computational in silico tools to predict spliceogenic variants leading to pseudoexons have limited efficiency. We assessed the performance of the SpliceAI tool combined with ESRseq scores to identify spliceogenic deep intronic variants by affecting cryptic sites or splicing regulatory elements (SREs) using literature and experimental datasets. Our results with 233 published deep intronic variants showed that SpliceAI, with a 0.05 threshold, predicts spliceogenic deep intronic variants affecting cryptic splice sites, but is less effective in detecting those affecting SREs. Next, we characterized the SRE profiles using ESRseq, showing that pseudoexons are significantly enriched in SRE-enhancers compared to adjacent intronic regions. Although the combination of SpliceAI with ESRseq scores (considering ∆ESRseq and SRE landscape) showed higher sensitivity, the global performance did not improve because of the higher number of false positives. The combination of both tools was tested in a tumor RNA dataset with 207 intronic variants disrupting splicing, showing a sensitivity of 86%. Following the pipeline, five spliceogenic deep intronic variants were experimentally identified from 33 variants in HBOC genes. Overall, our results provide a framework to detect deep intronic variants disrupting splicing.

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Topics: RNA splicing (50%)

Open accessJournal ArticleDOI: 10.1016/J.PRETEYERES.2021.101029
Abstract: Inherited retinal diseases (IRDs) are a clinically complex and heterogenous group of visual impairment phenotypes caused by pathogenic variants in at least 277 nuclear and mitochondrial genes, affecting different retinal regions, and depleting the vision of affected individuals. Genes that cause IRDs when mutated are unique by possessing differing genotype-phenotype correlations, varying inheritance patterns, hypomorphic alleles, and modifier genes thus complicating genetic interpretation. Next-generation sequencing has greatly advanced the identification of novel IRD-related genes and pathogenic variants in the last decade. For this review, we performed an in-depth literature search which allowed for compilation of the Global Retinal Inherited Disease (GRID) dataset containing 4798 discrete variants and 17,299 alleles published in 31 papers, showing a wide range of frequencies and complexities among the 194 genes reported in GRID, with 65% of pathogenic variants being unique to a single individual. A better understanding of IRD-related gene distribution, gene complexity, and variant types allow for improved genetic testing and therapies. Current genetic therapeutic methods are also quite diverse and rely on variant identification, and range from whole gene replacement to single nucleotide editing at the DNA or RNA levels. IRDs and their suitable therapies thus require a range of effective disease modelling in human cells, granting insight into disease mechanisms and testing of possible treatments. This review summarizes genetic and therapeutic modalities of IRDs, provides new analyses of IRD-related genes (GRID and complexity scores), and provides information to match genetic-based therapies such as gene-specific and variant-specific therapies to the appropriate individuals.

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Topics: Genetic testing (56%), Inheritance Patterns (52%)

Open accessJournal ArticleDOI: 10.3389/FGENE.2021.701652
Jin-Huan Lin1, Hao Wu1, Wen-Bin Zou1, Emmanuelle Masson2  +6 moreInstitutions (3)
Abstract: Combining data derived from a meta-analysis of human disease-associated 5' splice site GT>GC (i.e., +2T>C) variants and a cell culture-based full-length gene splicing assay (FLGSA) of forward engineered +2T>C substitutions, we recently estimated that ∼15-18% of +2T>C variants can generate up to 84% wild-type transcripts relative to their wild-type counterparts. Herein, we analyzed the splicing outcomes of 20 +2T>C variants that generate some wild-type transcripts in two minigene assays. We found a high discordance rate in terms of the generation of wild-type transcripts, not only between FLGSA and the minigene assays but also between the different minigene assays. In the pET01 context, all 20 wild-type minigene constructs generated the expected wild-type transcripts; of the 20 corresponding variant minigene constructs, 14 (70%) generated wild-type transcripts. In the pSPL3 context, only 18 of the 20 wild-type minigene constructs generated the expected wild-type transcripts whereas 8 of the 18 (44%) corresponding variant minigene constructs generated wild-type transcripts. Thus, in the context of a particular type of variant, we raise awareness of the limitations of minigene splicing assays and emphasize the importance of sequence context in regulating splicing. Whether or not our findings apply to other types of splice-altering variant remains to be investigated.

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Topics: Minigene (69%), RNA splicing (53%)

52 results found

Open accessJournal ArticleDOI: 10.1093/BIOINFORMATICS/BTP324
Heng Li1, Richard Durbin1Institutions (1)
01 Jul 2009-Bioinformatics
Abstract: Motivation: The enormous amount of short reads generated by the new DNA sequencing technologies call for the development of fast and accurate read alignment programs. A first generation of hash table-based methods has been developed, including MAQ, which is accurate, feature rich and fast enough to align short reads from a single individual. However, MAQ does not support gapped alignment for single-end reads, which makes it unsuitable for alignment of longer reads where indels may occur frequently. The speed of MAQ is also a concern when the alignment is scaled up to the resequencing of hundreds of individuals. Results: We implemented Burrows-Wheeler Alignment tool (BWA), a new read alignment package that is based on backward search with Burrows–Wheeler Transform (BWT), to efficiently align short sequencing reads against a large reference sequence such as the human genome, allowing mismatches and gaps. BWA supports both base space reads, e.g. from Illumina sequencing machines, and color space reads from AB SOLiD machines. Evaluations on both simulated and real data suggest that BWA is ~10–20× faster than MAQ, while achieving similar accuracy. In addition, BWA outputs alignment in the new standard SAM (Sequence Alignment/Map) format. Variant calling and other downstream analyses after the alignment can be achieved with the open source SAMtools software package. Availability: Contact: [email protected]

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Topics: Hybrid genome assembly (54%), Sequence assembly (53%), 2 base encoding (52%) ... read more

35,234 Citations

Open accessJournal ArticleDOI: 10.1038/GIM.2015.30
Sue Richards1, Nazneen Aziz2, Nazneen Aziz3, Sherri J. Bale4  +9 moreInstitutions (11)
Abstract: Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology

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11,349 Citations

Open accessJournal ArticleDOI: 10.1038/NG.2892
Martin Kircher1, Daniela Witten1, Preti Jain, Brian J. O'Roak2  +3 moreInstitutions (2)
01 Mar 2014-Nature Genetics
Abstract: Our capacity to sequence human genomes has exceeded our ability to interpret genetic variation. Current genomic annotations tend to exploit a single information type (e.g. conservation) and/or are restricted in scope (e.g. to missense changes). Here, we describe Combined Annotation Dependent Depletion (CADD), a framework that objectively integrates many diverse annotations into a single, quantitative score. We implement CADD as a support vector machine trained to differentiate 14.7 million high-frequency human derived alleles from 14.7 million simulated variants. We pre-compute “C-scores” for all 8.6 billion possible human single nucleotide variants and enable scoring of short insertions/deletions. C-scores correlate with allelic diversity, annotations of functionality, pathogenicity, disease severity, experimentally measured regulatory effects, and complex trait associations, and highly rank known pathogenic variants within individual genomes. The ability of CADD to prioritize functional, deleterious, and pathogenic variants across many functional categories, effect sizes and genetic architectures is unmatched by any current annotation.

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Topics: Genome-wide association study (54%), Genomics (51%)

4,148 Citations

Open accessJournal ArticleDOI: 10.1101/GR.097857.109
01 Jan 2010-Genome Research
Abstract: Methods for detecting nucleotide substitution rates that are faster or slower than expected under neutral drift are widely used to identify candidate functional elements in genomic sequences. However, most existing methods consider either reductions (conservation) or increases (acceleration) in rate but not both, or assume that selection acts uniformly across the branches of a phylogeny. Here we examine the more general problem of detecting departures from the neutral rate of substitution in either direction, possibly in a clade-specific manner. We consider four statistical, phylogenetic tests for addressing this problem: a likelihood ratio test, a score test, a test based on exact distributions of numbers of substitutions, and the genomic evolutionary rate profiling (GERP) test. All four tests have been implemented in a freely available program called phyloP. Based on extensive simulation experiments, these tests are remarkably similar in statistical power. With 36 mammalian species, they all appear to be capable of fairly good sensitivity with low false-positive rates in detecting strong selection at individual nucleotides, moderate selection in 3-bp elements, and weaker or clade-specific selection in longer elements. By applying phyloP to mammalian multiple alignments from the ENCODE project, we shed light on patterns of conservation/acceleration in known and predicted functional elements, approximate fractions of sites subject to constraint, and differences in clade-specific selection in the primate and glires clades. We also describe new "Conservation" tracks in the UCSC Genome Browser that display both phyloP and phastCons scores for genome-wide alignments of 44 vertebrate species.

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1,623 Citations

Journal ArticleDOI: 10.1007/BF00210743
01 Sep 1992-Human Genetics
Abstract: A total of 101 different examples of point mutations, which lie in the vicinity of mRNA splice junctions, and which have been held to be responsible for a human genetic disease by altering the accuracy of efficiency of mRNA splicing, have been collated. These data comprise 62 mutations at 5′ splice sites, 26 at 3′ splice sites and 13 that result in the creation of novel splice sites. It is estimated that up to 15% of all point mutations causing human genetic disease result in an mRNA splicing defect. Of the 5′ splice site mutations, 60% involved the invariant GT dinucleotide; mutations were found to be non-randomly distributed with an excess over expectation at positions +1 and +2, and apparent deficiencies at positions −1 and −2. Of the 3′ splice site mutations, 87% involved the invariant AG dinucleotide; an excess of mutations over expectation was noted at position -2. This non-randomness of mutation reflects the evolutionary conservation apparent in splice site consensus sequences drawn up previously from primate genes, and is most probably attributable to detection bias resulting from the differing phenotypic severity of specific lesions. The spectrum of point mutations was also drastically skewed: purines were significantly overrepresented as substituting nucleotides, perhaps because of steric hindrance (e.g. in U1 snRNA binding at 5′ splice sites). Furthermore, splice sites affected by point mutations resulting in human genetic disease were markedly different from the splice site consensus sequences. When similarity was quantified by a ‘consensus value’, both extremely low and extremely high values were notably absent from the wild-type sequences of the mutated splice sites. Splice sites of intermediate similarity to the consensus sequence may thus be more prone to the deleterious effects of mutation. Regarding the phenotypic effects of mutations on mRNA splicing, exon skipping occurred more frequently than cryptic splice site usage. Evidence is presented that indicates that, at least for 5′ splice site mutations, cryptic splice site usage is favoured under conditions where (1) a number of such sites are present in the immediate vicinity and (2) these sites exhibit sufficient homology to the splice site consensus sequence for them to be able to compete successfully with the mutated splice site. The novel concept of a “potential for cryptic splice site usage” value was introduced in order to quantify these characteristics, and to predict the relative proportion of exon skipping vs cryptic splice site utilization consequent to the introduction of a mutation at a normal splice site.

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Topics: Splice site mutation (71%), splice (62%), Consensus sequence (53%) ... read more

1,282 Citations