Several new high-quality human genome assemblies produce ethnicity-specific reference sequences and show how scientists can use this genetic information to improve precision medicine studies in Asian sub- populations. These projects demonstrate how long- read SMRT Sequencing provides robust detection of polymorphic structural variants in clinically relevant gene coding regions and phases variants into haplotypes.
Explore the types of human genomic variation and the diseases known to be caused by structural variants.
Explore how long-read sequencing enables solving of rare and mendelian diseases.
We report a family with progressive myoclonic epilepsy who underwent whole-exome sequencing but was negative for pathogenic variants. Similar clinical courses of a devastating neurodegenerative phenotype of two affected siblings were highly suggestive of a genetic etiology, which indicates that the survey of genetic variation by whole-exome sequencing was not comprehensive. To investigate the presence of a variant that remained unrecognized by standard genetic testing, PacBio long-read sequencing was performed. Structural variant (SV) detection using low-coverage (6×) whole-genome sequencing called 17,165 SVs (7,216 deletions and 9,949 insertions). Our SV selection narrowed down potential candidates to only five SVs (two deletions…
Long-read sequencing technology is now capable of reading single-molecule DNA with an average read length of more than 10?kb, fully enabling the coverage of large structural variations (SVs). This advantage may pave the way for the detection of unprecedented SVs as well as repeat expansions. Pathogenic SVs of only known genes used to be selectively analyzed based on prior knowledge of target DNA sequence. The unbiased application of long-read whole-genome sequencing (WGS) for the detection of pathogenic SVs has just begun. Here, we apply PacBio SMRT sequencing in a Japanese family with benign adult familial myoclonus epilepsy (BAFME). Our SV…
In this ASHG workshop presentation, Janet Song of Stanford School of Medicine shared research on resolving a tandem repeat array implicated in bipolar disorder and schizophrenia. These psychiatric diseases share a number of genomic risk variants, she noted, but scientists continue to search for a specific causal variant in the CACNA1C gene suggested by previous genome-wide association studies. SMRT Sequencing of this region in 16 individuals identified a series of 30-mer repeats, containing a total of about 50 variants. Analysis showed that 10 variants were linked to protective or risk haplotypes. Song aims to study the function of these variants…
In this video, PacBio scientists present ongoing improvements to the Integrative Genomics Viewer (IGV) and demonstrate how multiple new features improve visualization support for PacBio long-read sequencing data. The video describes these recent updates which include; quick consensus accuracy mode to hide random single-molecule errors, direct phasing of haplotypes using long-read evidence, and visual annotation of insertions and deletions relative to the reference with enumeration of gap size for individual reads. These new features are available now in the development version of IGV, which can be found at http://software.broadinstitute.org/software/igv/download_snapshot. The Sequel sequencing data used in this demonstration is also publicly…
PacBio bioinformatician Aaron Wenger presents this ASHG 2016 poster demonstrating human structural variation detection at varying coverage levels with SMRT Sequencing on the Sequel System. Results were compared to truth sets for well-characterized genomes. Results indicate that even low coverage of SMRT Sequencing makes it possible to detect hundreds of SVs that are missed in high-coverage short-read sequencing data.
In this ASHG 2017 presentation, Jonas Korlach, the CSO of PacBio shared updates on three applications featuring SMRT Sequencing on the Sequel System, highlighting structural variant detection, targeted sequencing and the Iso-Seq method of RNA sequencing. He provided details on structural variant calling using pbsv to call insertions and deletions and compared PacBio variant calling with other technologies. Korlach described how targeted sequencing can be used to interrogate repeat expansions, detect and phase minor variants and can access medically relevant but previously inaccessible gene targets. He presented research featuring the Iso-Seq method that identified isoforms, corrected previous isoform annotations and…
In this ASHG 2017 presentation, Han Brunner of Radboud University Medical Center presented research using SMRT Sequencing to detect structural variants to uncover the genetic causes of intellectual disability. He shared that long-read sequencing enabled detection of 25,000 structural variants per genome. Brunner presented data from patient trios to identify de novo structural variant candidates and ongoing validation work to determine the causative mutations of intellectual disability.
In this ASHG 2017 presentation, Charles Lee of The Jackson Laboratory for Genomic Medicine presented work from the Human Genome Structural Variation Consortium. He shared data from efforts to utilize multiple platforms for the comprehensive discovery of structural variations—including insertions, deletions, inversions and mobile element insertions—in individual genomes. By combining various technologies, this research identified 7 times more structural variation per person than was previously known to exist.
In this video, Aaron Wenger, a research scientist at PacBio, describes the use of long-read SMRT Sequencing to detect structural variants in the human genome. He shares that structural variations – such as insertions and deletions – impact human traits, cause disease, and differentiate humans from other species. Wenger highlights the use of SMRT Sequencing and structural variant calling software tools in a collaboration with Stanford University which identified a disease-causing genetic mutation.
In this video Aaron Wenger describes the new structural variant detection application, known as pbsv, available in SMRT Link v5.0. This application identifies large (default: =50 bp) insertions and deletions in a sample relative to a reference from whole genome sequence data. Aaron details pbsv commands and use of the application in SMRT Link.
Explore human genetic variation and learn how SMRT Sequencing uncovers the full spectrum of structural variation to advance understanding of genetic disease and broaden our knowledge of human diversity.