Mind the gaps – ignoring errors in long read assemblies critically affects protein prediction

Abstract Single-molecule sequencing technologies have recently been commercialized by Pacific Biosciences and Oxford Nanopore with the promise of sequencing long DNA fragments (kilobases to megabases order) and then, using efficient algorithms, provide high quality assemblies in terms of contiguity and completeness of repetitive regions. However, the error rate of long-read technologies is higher than that of short-read technologies. This has a direct consequence on the base quality of genome assemblies, particularly in coding regions where sequencing errors can disrupt the coding frame of genes. In the case of diploid genomes, the consensus of a given gene can be a mixture between the two haplotypes and can lead to premature stop codons. Several methods have been developed to polish genome assemblies using short reads and generally, they inspect the nucleotide one by one, and provide a correction for each nucleotide of the input assembly. As a result, these algorithms are not able to properly process diploid genomes and they typically switch from one haplotype to another. Herein we proposed Hapo-G (Haplotype-Aware Polishing Of Genomes), a new algorithm capable of incorporating phasing information from high-quality reads (short or long-reads) to polish genome assemblies and in particular assemblies of diploid and heterozygous genomes.

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Comparison of Exome and Genome Sequencing Technologies for the Complete Capture of Protein‐Coding Regions

Human Mutation ◽

10.1002/humu.22813 ◽

2015 ◽

Vol 36 (8) ◽

pp. 815-822 ◽

Cited By ~ 96

Author(s):

Stefan H. Lelieveld ◽

Malte Spielmann ◽

Stefan Mundlos ◽

Joris A. Veltman ◽

Christian Gilissen

Keyword(s):

Genome Sequencing ◽

Protein Coding ◽

Coding Regions ◽

Sequencing Technologies

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Long-read sequencing across the C9orf72 ‘GGGGCC’ repeat expansion: implications for clinical use and genetic discovery efforts in human disease

10.1101/176651 ◽

2018 ◽

Cited By ~ 1

Author(s):

Mark T. W. Ebbert ◽

Stefan Farrugia ◽

Jonathon Sens ◽

Karen Jansen-West ◽

Tania F. Gendron ◽

...

Keyword(s):

Whole Genome Sequencing ◽

Genome Sequencing ◽

Repeat Expansion ◽

Whole Genome ◽

Short Read ◽

Short Read Sequencing ◽

Sequencing Technologies ◽

Long Read ◽

Repeat Expansions ◽

Targeted Approach

AbstractBackground: Many neurodegenerative diseases are caused by nucleotide repeat expansions, but most expansions, like the C9orf72 ‘GGGGCC’ (G4C2) repeat that causes approximately 5-7% of all amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) cases, are too long to sequence using short-read sequencing technologies. It is unclear whether long-read sequencing technologies can traverse these long, challenging repeat expansions. Here, we demonstrate that two long-read sequencing technologies, Pacific Biosciences’ (PacBio) and Oxford Nanopore Technologies’ (ONT), can sequence through disease-causing repeats cloned into plasmids, including the FTD/ALS-causing G4C2 repeat expansion. We also report the first long-read sequencing data characterizing the C9orf72 G4C2 repeat expansion at the nucleotide level in two symptomatic expansion carriers using PacBio whole-genome sequencing and a no-amplification (No-Amp) targeted approach based on CRISPR/Cas9.Results: Both the PacBio and ONT platforms successfully sequenced through the repeat expansions in plasmids. Throughput on the MinlON was a challenge for whole-genome sequencing; we were unable to attain reads covering the human C9orf72 repeat expansion using 15 flow cells. We obtained 8x coverage across the C9orf72 locus using the PacBio Sequel, accurately reporting the unexpanded allele at eight repeats, and reading through the entire expansion with 1324 repeats (7941 nucleotides). Using the No-Amp targeted approach, we attained >800x coverage and were able to identify the unexpanded allele, closely estimate expansion size, and assess nucleotide content in a single experiment. We estimate the individual’s repeat region was >99% G4C2 content, though we cannot rule out small interruptions.Conclusions: Our findings indicate that long-read sequencing is well suited to characterizing known repeat expansions, and for discovering new disease-causing, disease-modifying, or risk-modifying repeat expansions that have gone undetected with conventional short-read sequencing. The PacBio No-Amp targeted approach may have future potential in clinical and genetic counseling environments. Larger and deeper long-read sequencing studies in C9orf72 expansion carriers will be important to determine heterogeneity and whether the repeats are interrupted by non-G4C2 content, potentially mitigating or modifying disease course or age of onset, as interruptions are known to do in other repeat-expansion disorders. These results have broad implications across all diseases where the genetic etiology remains unclear.

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Evaluation of Single-Molecule Sequencing Technologies for Structural Variant Detection in Two Swedish Human Genomes

Genes ◽

10.3390/genes11121444 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1444

Author(s):

Nazeefa Fatima ◽

Anna Petri ◽

Ulf Gyllensten ◽

Lars Feuk ◽

Adam Ameur

Keyword(s):

Whole Genome Sequencing ◽

Genome Sequencing ◽

Single Molecule ◽

Large Scale ◽

Whole Genome Sequencing Data ◽

Whole Genome ◽

Sequencing Data ◽

Structural Variations ◽

Single Molecule Sequencing ◽

Human Samples

Long-read single molecule sequencing is increasingly used in human genomics research, as it allows to accurately detect large-scale DNA rearrangements such as structural variations (SVs) at high resolution. However, few studies have evaluated the performance of different single molecule sequencing platforms for SV detection in human samples. Here we performed Oxford Nanopore Technologies (ONT) whole-genome sequencing of two Swedish human samples (average 32× coverage) and compared the results to previously generated Pacific Biosciences (PacBio) data for the same individuals (average 66× coverage). Our analysis inferred an average of 17k and 23k SVs from the ONT and PacBio data, respectively, with a majority of them overlapping with an available multi-platform SV dataset. When comparing the SV calls in the two Swedish individuals, we find a higher concordance between ONT and PacBio SVs detected in the same individual as compared to SVs detected by the same technology in different individuals. Downsampling of PacBio reads, performed to obtain similar coverage levels for all datasets, resulted in 17k SVs per individual and improved overlap with the ONT SVs. Our results suggest that ONT and PacBio have a similar performance for SV detection in human whole genome sequencing data, and that both technologies are feasible for population-scale studies.

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Longshot enables accurate variant calling in diploid genomes from single-molecule long read sequencing

Nature Communications ◽

10.1038/s41467-019-12493-y ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 26

Author(s):

Peter Edge ◽

Vikas Bansal

Keyword(s):

Single Molecule ◽

Variant Calling ◽

Small Scale ◽

Whole Genome ◽

Limited Information ◽

Single Nucleotide Variants ◽

Pacific Biosciences ◽

Sequencing Technologies ◽

Long Reads ◽

Long Read

Abstract Whole-genome sequencing using sequencing technologies such as Illumina enables the accurate detection of small-scale variants but provides limited information about haplotypes and variants in repetitive regions of the human genome. Single-molecule sequencing (SMS) technologies such as Pacific Biosciences and Oxford Nanopore generate long reads that can potentially address the limitations of short-read sequencing. However, the high error rate of SMS reads makes it challenging to detect small-scale variants in diploid genomes. We introduce a variant calling method, Longshot, which leverages the haplotype information present in SMS reads to accurately detect and phase single-nucleotide variants (SNVs) in diploid genomes. We demonstrate that Longshot achieves very high accuracy for SNV detection using whole-genome Pacific Biosciences data, outperforms existing variant calling methods, and enables variant detection in duplicated regions of the genome that cannot be mapped using short reads.

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Hapo-G, Haplotype-Aware Polishing Of Genome Assemblies

10.1101/2020.12.14.422624 ◽

2020 ◽

Author(s):

Jean-Marc Aury ◽

Benjamin Istace

Keyword(s):

Single Molecule ◽

Direct Consequence ◽

Short Reads ◽

Sequencing Errors ◽

Coding Regions ◽

Sequencing Technologies ◽

Oxford Nanopore ◽

Long Read ◽

Genome Assemblies

Single-molecule sequencing technologies have recently been commercialized by Pacific Biosciences and Oxford Nanopore with the promise of sequencing long DNA fragments (kilobases to megabases order) and then, using efficient algorithms, provide high quality assemblies in terms of contiguity and completeness of repetitive regions. However, the error rate of long-read technologies is higher than that of short-read technologies. This has a direct consequence on the base quality of genome assemblies, particularly in coding regions where sequencing errors can disrupt the coding frame of genes. In the case of diploid genomes, the consensus of a given gene can be a mixture between the two haplotypes and can lead to premature stop codons. Several methods have been developed to polish genome assemblies using short reads and generally, they inspect the nucleotide one by one, and provide a correction for each nucleotide of the input assembly. As a result, these algorithms are not able to properly process diploid genomes and they typically switch from one haplotype to another. Herein we proposed Hapo-G (Haplotype-Aware Polishing Of Genomes), a new algorithm capable of incorporating phasing information from short reads to polish genome assemblies and in particular assemblies of diploid and heterozygous genomes.

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Long-read whole-genome sequencing identified a partial MBD5 deletion in an exome-negative patient with neurodevelopmental disorder

Journal of Human Genetics ◽

10.1038/s10038-020-00893-8 ◽

2021 ◽

Author(s):

Sachiko Ohori ◽

Rie S. Tsuburaya ◽

Masako Kinoshita ◽

Etsuko Miyagi ◽

Takeshi Mizuguchi ◽

...

Keyword(s):

Whole Genome Sequencing ◽

Genome Sequencing ◽

Neurodevelopmental Disorder ◽

Whole Genome ◽

Negative Patient ◽

Long Read

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Comprehensive identification of transposable element insertions using multiple sequencing technologies

Nature Communications ◽

10.1038/s41467-021-24041-8 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Chong Chu ◽

Rebeca Borges-Monroy ◽

Vinayak V. Viswanadham ◽

Soohyun Lee ◽

Heng Li ◽

...

Keyword(s):

Transposable Element ◽

Structure And Function ◽

Endogenous Retroviruses ◽

Whole Genome Sequencing Data ◽

Whole Genome ◽

Sequencing Data ◽

Short Read ◽

Sequencing Technologies ◽

Long Read ◽

And Function

AbstractTransposable elements (TEs) help shape the structure and function of the human genome. When inserted into some locations, TEs may disrupt gene regulation and cause diseases. Here, we present xTea (x-Transposable element analyzer), a tool for identifying TE insertions in whole-genome sequencing data. Whereas existing methods are mostly designed for short-read data, xTea can be applied to both short-read and long-read data. Our analysis shows that xTea outperforms other short read-based methods for both germline and somatic TE insertion discovery. With long-read data, we created a catalogue of polymorphic insertions with full assembly and annotation of insertional sequences for various types of retroelements, including pseudogenes and endogenous retroviruses. Notably, we find that individual genomes have an average of nine groups of full-length L1s in centromeres, suggesting that centromeres and other highly repetitive regions such as telomeres are a significant yet unexplored source of active L1s. xTea is available at https://github.com/parklab/xTea.

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Survey of the Bradysia odoriphaga Transcriptome Using PacBio Single-Molecule Long-Read Sequencing

Genes ◽

10.3390/genes10060481 ◽

2019 ◽

Vol 10 (6) ◽

pp. 481 ◽

Cited By ~ 1

Author(s):

Chen ◽

Lin ◽

Xie ◽

Zhong ◽

Zhang ◽

...

Keyword(s):

Insecticide Resistance ◽

Single Molecule ◽

Functional Categories ◽

Genetic Studies ◽

Sequencing Technologies ◽

Clusters Of Orthologous Groups ◽

Long Read ◽

Main Gene ◽

First Time ◽

Main Factor

The damage caused by Bradysia odoriphaga is the main factor threatening the production of vegetables in the Liliaceae family. However, few genetic studies of B. odoriphaga have been conducted because of a lack of genomic resources. Many long-read sequencing technologies have been developed in the last decade; therefore, in this study, the transcriptome including all development stages of B. odoriphaga was sequenced for the first time by Pacific single-molecule long-read sequencing. Here, 39,129 isoforms were generated, and 35,645 were found to have annotation results when checked against sequences available in different databases. Overall, 18,473 isoforms were distributed in 25 various Clusters of Orthologous Groups, and 11,880 isoforms were categorized into 60 functional groups that belonged to the three main Gene Ontology classifications. Moreover, 30,610 isoforms were assigned into 44 functional categories belonging to six main Kyoto Encyclopedia of Genes and Genomes functional categories. Coding DNA sequence (CDS) prediction showed that 36,419 out of 39,129 isoforms were predicted to have CDS, and 4319 simple sequence repeats were detected in total. Finally, 266 insecticide resistance and metabolism-related isoforms were identified as candidate genes for further investigation of insecticide resistance and metabolism in B. odoriphaga.

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Detecting a long insertion variant in SAMD12 by SMRT sequencing: implications of long-read whole-genome sequencing for repeat expansion diseases

Journal of Human Genetics ◽

10.1038/s10038-018-0551-7 ◽

2018 ◽

Vol 64 (3) ◽

pp. 191-197 ◽

Cited By ~ 12

Author(s):

Takeshi Mizuguchi ◽

Tomoko Toyota ◽

Hiroaki Adachi ◽

Noriko Miyake ◽

Naomichi Matsumoto ◽

...

Keyword(s):

Whole Genome Sequencing ◽

Genome Sequencing ◽

Repeat Expansion ◽

Whole Genome ◽

Smrt Sequencing ◽

Long Read

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