scholarly journals Nanopore sequencing undergoes catastrophic sequence failure at inverted duplicated DNA sequences

2019 ◽  
Author(s):  
Pieter Spealman ◽  
Jaden Burrell ◽  
David Gresham
Keyword(s):  
Dna Sequences ◽  
Copy Number ◽  
Copy Number Variants ◽  
Nanopore Sequencing ◽  
Aberrant Behavior ◽  
Structural Variants ◽  
Dna Structures ◽  
Secondary Dna Structures

Inverted duplicated sequences are a common feature of structural variants (SVs) and copy number variants (CNVs). Analysis of CNVs containing inverted duplicated sequences using nanopore sequencing identified recurrent aberrant behavior characterized by incorrect and low confidence base calls that result from a systematic elevation in the current recorded by the sequencing pore. The coincidence of inverted duplicated sequences with catastrophic sequence failure suggests that secondary DNA structures may impair transit through the nanopore.

scholarly journals Inverted duplicate DNA sequences increase translocation rates through sequencing nanopores resulting in reduced base calling accuracy

2020 ◽  
Vol 48 (9) ◽  
pp. 4940-4945
Author(s):  
Pieter Spealman ◽  
Jaden Burrell ◽  
David Gresham
Keyword(s):  
Dna Sequences ◽  
Copy Number ◽  
Copy Number Variants ◽  
Electrical Current ◽  
Nanopore Sequencing ◽  
Aberrant Behavior ◽  
Structural Variants ◽  
Dna Structures ◽  
Base Calling ◽  
Secondary Dna Structures

Abstract Inverted duplicated DNA sequences are a common feature of structural variants (SVs) and copy number variants (CNVs). Analysis of CNVs containing inverted duplicated DNA sequences using nanopore sequencing identified recurrent aberrant behavior characterized by low confidence, incorrect and missed base calls. Inverted duplicate DNA sequences in both yeast and human samples were observed to have systematic elevation in the electrical current detected at the nanopore, increased translocation rates and decreased sampling rates. The coincidence of inverted duplicated DNA sequences with dramatically reduced sequencing accuracy and an increased translocation rate suggests that secondary DNA structures may interfere with the dynamics of transit of the DNA through the nanopore.

scholarly journals Detection of single nucleotide and copy number variants in the Fabry disease-associated GLA gene using nanopore sequencing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Albina Nowak ◽  
Omer Murik ◽  
Tzvia Mann ◽  
David A. Zeevi ◽  
Gheona Altarescu
Keyword(s):  
Fabry Disease ◽  
Copy Number ◽  
New Technology ◽  
Copy Number Variants ◽  
Cost Effective ◽  
Nanopore Sequencing ◽  
Oxford Nanopore ◽  
Long Read ◽  
Sanger Sequence ◽  
Gla Gene

AbstractMore than 900 variants have been described in the GLA gene. Some intronic variants and copy number variants in GLA can cause Fabry disease but will not be detected by classical Sanger sequence. We aimed to design and validate a method for sequencing the GLA gene using long-read Oxford Nanopore sequencing technology. Twelve Fabry patients were blindly analyzed, both by conventional Sanger sequence and by long-read sequencing of a 13 kb PCR amplicon. We used minimap2 to align the long-read data and Nanopolish and Sniffles to call variants. All the variants detected by Sanger (including a deep intronic variant) were also detected by long-read sequencing. One patient had a deletion that was not detected by Sanger sequencing but was detected by the new technology. Our long-read sequencing-based method was able to detect missense variants and an exonic deletion, with the added advantage of intronic analysis. It can be used as an efficient and cost-effective tool for screening and diagnosing Fabry disease.

scholarly journals Detection of Single Nucleotide and Copy Number Variants in the Fabry Disease-associated GLA Gene Using Nanopore Sequencing

2021 ◽  
Author(s):  
Albina Nowak ◽  
Omer Murik ◽  
Tzvia Mann ◽  
David A. Zeevi ◽  
Gheona Altarescu
Keyword(s):  
Fabry Disease ◽  
Copy Number ◽  
New Technology ◽  
Copy Number Variants ◽  
Cost Effective ◽  
Nanopore Sequencing ◽  
Oxford Nanopore ◽  
Long Read ◽  
Sanger Sequence ◽  
Gla Gene

Abstract Introduction: More than one thousand variants have been described in the GLA gene. Some intronic variants and copy number variants in GLA can cause Fabry disease but will not be detected by classical Sanger sequence.Aims: We aimed to design and validate a method for sequencing the GLA gene using long read Oxford Nanopore sequencing technology.Methods: Twelve Fabry patients were blindly analyzed, both by conventional Sanger sequence and by long read sequencing of a 13kb PCR amplicon. We used minimap2 to align the long read data and Nanopolish and Sniffles to call variants.Results: All the variants detected by Sanger (including a deep intronic variant) were also detected by long read sequencing. One patient had a deletion that was not detected by Sanger sequencing but was detected by the new technology.Conclusions: Our long read sequencing-based method was able to detect missense variants and an exonic deletion, with the added advantage of intronic analysis. It can be used as an efficient and cost-effective tool for screening and diagnosing Fabry disease.

scholarly journals Enrichment of non-B-form DNA at D. melanogaster centromeres

2021 ◽  
Author(s):  
Venkata S. P. Patchigolla ◽  
Barbara G. Mellone
Keyword(s):  
Dna Sequences ◽  
Protein A ◽  
Secondary Structures ◽  
Eukaryotic Cell ◽  
Dna Melting ◽  
Dna Structures ◽  
Histone H3 Variant ◽  
Centromeric Protein ◽  
Dna Secondary Structures ◽  
Secondary Dna Structures

Centromeres are essential chromosomal regions that mediate the accurate inheritance of genetic information during eukaryotic cell division. Despite their conserved function, centromeres do not contain conserved DNA sequences and are instead epigenetically marked by the presence of the centromere-specific histone H3 variant CENP-A (centromeric protein A). The functional contribution of centromeric DNA sequences to centromere identity remains elusive. Previous work found that dyad symmetries with a propensity to adopt non-canonical secondary DNA structures are enriched at the centromeres of several species. These findings lead to the proposal that such non-canonical DNA secondary structures may contribute to centromere specification. Here, we analyze the predicted secondary structures of the recently identified centromere DNA sequences from Drosophila melanogaster. Although dyad symmetries are only enriched on the Y centromere, we find that other types of non-canonical DNA structures, including DNA melting and G-quadruplexes, are common features of all D. melanogaster centromeres. Our work is consistent with previous models suggesting that non-canonical DNA secondary structures may be conserved features of centromeres with possible implications for centromere specification.

scholarly journals Copy number variants outperform SNPs to reveal genotype-temperature association in a marine species

2020 ◽  
Author(s):  
Yann Dorant ◽  
Hugo Cayuela ◽  
Kyle Wellband ◽  
Martin Laporte ◽  
Quentin Rougemont ◽  
...  
Keyword(s):  
Population Structure ◽  
Local Adaptation ◽  
Copy Number ◽  
Genotypic Variation ◽  
Copy Number Variants ◽  
Marine Species ◽  
Homarus Americanus ◽  
Snp Markers ◽  
Structural Variants

AbstractCopy number variants (CNVs) are a major component of genotypic and phenotypic variation in genomes. To date, our knowledge of genotypic variation and evolution has largely been acquired by means of single nucleotide polymorphism (SNPs) analyses. Until recently, the adaptive role of structural variants (SVs) and particularly that of CNVs has been overlooked in wild populations, partly due to their challenging identification. Here, we document the usefulness of Rapture, a derived reduced-representation shotgun sequencing approach, to detect and investigate copy number variants (CNVs) alongside SNPs in American lobster (Homarus americanus) populations. We conducted a comparative study to examine the potential role of SNPs and CNVs in local adaptation by sequencing 1,141 lobsters from 21 sampling sites within the southern Gulf of St. Lawrence, which experiences the highest yearly thermal variance of the Canadian marine coastal waters. Our results demonstrated that CNVs accounts for higher genetic differentiation than SNP markers. Contrary to SNPs, for which no significant genetic-environment association was found, 48 CNV candidates were significantly associated with the annual variance of sea surface temperature, leading to the genetic clustering of sampling locations despite their geographic separation. Altogether, we provide a strong empirical case that CNVs putatively contribute to local adaptation in marine species and unveil stronger spatial signal of population structure than SNPs. Our study provides the means to study CNVs in non-model species and highlights the importance of considering structural variants alongside SNPs to enhance our understanding of ecological and evolutionary processes shaping adaptive population structure.

scholarly journals Automated prediction of the clinical impact of structural copy number variations

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
M. Gažiová ◽  
T. Sládeček ◽  
O. Pös ◽  
M. Števko ◽  
W. Krampl ◽  
...  
Keyword(s):  
Copy Number ◽  
Genetic Diseases ◽  
Copy Number Variants ◽  
Prediction Method ◽  
Copy Number Gain ◽  
Copy Number Variations ◽  
Copy Number Loss ◽  
Structural Variants ◽  
Uncertain Significance

AbstractCopy number variants (CNVs) play an important role in many biological processes, including the development of genetic diseases, making them attractive targets for genetic analyses. The interpretation of the effect of these structural variants is a challenging problem due to highly variable numbers of gene, regulatory, or other genomic elements affected by the CNV. This led to the demand for the interpretation tools that would relieve researchers, laboratory diagnosticians, genetic counselors, and clinical geneticists from the laborious process of annotation and classification of CNVs. We designed and validated a prediction method (ISV; Interpretation of Structural Variants) that is based on boosted trees which takes into account annotations of CNVs from several publicly available databases. The presented approach achieved more than 98% prediction accuracy on both copy number loss and copy number gain variants while also allowing CNVs being assigned “uncertain” significance in predictions. We believe that ISV’s prediction capability and explainability have a great potential to guide users to more precise interpretations and classifications of CNVs.

scholarly journals Template switching mechanism drives the tandem amplification of chromosome 20q11.21 in human pluripotent stem cells

2020 ◽  
Author(s):  
Jason A Halliwell ◽  
Duncan Baker ◽  
Kim Judge ◽  
Michael A Quail ◽  
Karen Oliver ◽  
...  
Keyword(s):  
Stem Cells ◽  
Pluripotent Stem Cells ◽  
Copy Number ◽  
Copy Number Variants ◽  
Genomic Region ◽  
Human Pluripotent Stem Cells ◽  
Genomic Rearrangements ◽  
Template Switching ◽  
Nanopore Sequencing ◽  
Specific Mechanism

AbstractCopy number variants (CNVs) are genomic rearrangements implicated in numerous congenital and acquired diseases, including cancer. In human pluripotent stem cells (PSC), the appearance of culture-acquired CNVs prompted concerns for their use in regenerative medicine applications. A particularly common problem in PSC is the occurrence of CNVs in the q11.21 region of chromosome 20. However, the exact mechanisms of origin of this amplicon remains elusive due to the difficulty in delineating its sequence and breakpoints. Here, we used long-range Nanopore sequencing on two examples of this CNV, present as a duplication in one and a triplication in another line. The CNVs were arranged in a head-to-tail orientation in both lines, with sequences of microhomologies flanking or overlapping both the proximal and distal breakpoints. These breakpoint signatures point to a specific mechanism of template switching in CNV formation, with surrounding Alu sequences likely contributing to the instability of this genomic region.

Understanding Schizophrenia: Genetic Causes and Treatment

2019 ◽  
Vol 1 (1) ◽  
pp. 6-12
Author(s):  
Fatima Javeria ◽  
Shazma Altaf ◽  
Alishah Zair ◽  
Rana Khalid Iqbal
Keyword(s):  
Copy Number ◽  
Drug Targets ◽  
Disease Risk ◽  
Mental Disease ◽  
Copy Number Variants ◽  
Aminobutyric Acid ◽  
Epigenetic Mechanisms ◽  
Gamma Aminobutyric Acid ◽  
Wide Range ◽  
Severe Mental Disease

Schizophrenia is a severe mental disease. The word schizophrenia literally means split mind. There are three major categories of symptoms which include positive, negative and cognitive symptoms. The disease is characterized by symptoms of hallucination, delusions, disorganized thinking and speech. Schizophrenia is related to many other mental and psychological problems like suicide, depression, hallucinations. Including these, it is also a problem for the patient’s family and the caregiver. There is no clear reason for the disease, but with the advances in molecular genetics; certain epigenetic mechanisms are involved in the pathophysiology of the disease. Epigenetic mechanisms that are mainly involved are the DNA methylation, copy number variants. With the advent of GWAS, a wide range of SNPs is found linked with the etiology of schizophrenia. These SNPs serve as ‘hubs’; because these all are integrating with each other in causing of schizophrenia risk. Until recently, there is no treatment available to cure the disease; but anti-psychotics can reduce the disease risk by minimizing its symptoms. Dopamine, serotonin, gamma-aminobutyric acid, are the neurotransmitters which serve as drug targets in the treatment of schizophrenia. Due to the involvement of genetic and epigenetic mechanisms, drugs available are already targeting certain genes involved in the etiology of the disease.

Koduojančios ir nekoduojančios genomo sekos variantų bei kopijų skaičiaus pokyčių molekulinis ir funkcinis vertinimas

2020 ◽  
Author(s):  
◽  
Evelina Siavrienė
Keyword(s):  
Genome Sequence ◽  
Copy Number ◽  
Copy Number Variants ◽  
Sequence Variants ◽  
Functional Evaluation

A Molecular and Functional Evaluation of Coding and Non-Coding Genome Sequence Variants and Copy Number Variants

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