Dan Geraghty explains that while there have been decades’ worth of studies associating the genetics of the major histocompatibility complex (MHC), and the highly polymorphic HLA class 1 and 2 genes, we still haven’t found the key mutations for a variety of different autoimmune diseases such as type 1 diabetes, rheumatoid arthritis, multiple sclerosis, and others. Enormous amounts of linkage disequilibrium in these regions are one factor, as is getting information in phase, so larger stretches of sequence are needed. Recently Geraghty has begun using SMRT Technology with hopes of drilling down to the causal genetics.
Jim Lupski is a professor at Baylor College of Medicine where he’s on the frontline of incorporating genomic research into everyday clinical practice. The story begins with Jim’s own genome, which is perhaps the most sequenced genome ever. Jim’s life as a leading genomic researcher has been driven in part for a strong personal reason. He has a rare genetic disease named after three researchers who first defined it, Charcot Marie Tooth Neuropathy. What began as a personal journey to uncover the source of his own disease led Jim to seminal work that launched the field of structural variation. Working…
Adam Ameur talks about a range of applications for which SMRT Sequencing had been useful in the SciLifeLab. Examples include analyzing a DNA translocation in chronic myeloid leukemia samples; studying the HPV genome; and sequencing the FADS region to understand fatty acid production.
Michael Schatz of Cold Spring Harbor Laboratory and Johns Hopkins University discusses the challenges in detecting structural variations (SVs) in high throughput sequencing data, especially more complex SVs such as a duplication nested within an inversion. To overcome these challenges, Dr. Schatz and his team have been applying long-read sequencing to analyze SVs in a range of samples from small microbial genomes, through mid-sized plant and animal genomes, to large mammalian genomes. The increased read lengths, which currently average over 10kbp and some approach 100kbp, make it possible to span more complex SVs and accurately assess SVs in repetitive regions,…
In this poster presentation, PacBio scientist Ellen Paxinos describes an improved algorithm for circular consensus reads. Using this new algorithm, dubbed CCS2, it is possible to reach arbitrarily high quality across longer insert lengths at a lower cost and higher throughput than Sanger Sequencing. She shows results from the application of CCS2 to the characterization of the HIV-1 K103N drug-resistance associated mutation, which is both important clinically, and represents a challenge due to regional sequence context.
Steve Kujawa from PacBio presents an AGBT poster reporting a study that characterized the use of SMRT Sequencing for the detection of low-frequency somatic variants. A multiplexed reference standard was amplified using the Multiplicom assay and sequenced on both the PacBio RS II and MiSeq System. Results indicate good concordance between the sequencing platforms, even at very low mutation frequencies.
PacBio Sequencing is characterized by very long sequence reads (averaging > 10,000 bases), lack of GC-bias, and high consensus accuracy. These features have allowed the method to provide a new gold standard in de novo genome assemblies, producing highly contiguous (contig N50 > 1 Mb) and accurate (> QV 50) genome assemblies. We will briefly describe the technology and then highlight the full workflow, from sample preparation through sequencing to data analysis, on examples of insect genome assemblies, and illustrate the difference these high-quality genomes represent with regard to biological insights, compared to fragmented draft assemblies generated by short-read sequencing.
PacBio’s Jenny Ekholm presents this ASHG 2016 poster on a new method being developed that enriches for unamplified DNA and uses SMRT Sequencing to characterize repeat expansion disorders. Incorporating the CRISPR/Cas9 system to target specific genes allows for amplification-free enrichment to preserve epigenetic information and avoid PCR bias. Internal studies have shown that the approach can successfully be used to target and sequence the CAG repeat responsible for Huntington’s disease, the repeat associated with ALS, and more. The approach allows for pooling many samples and sequencing with a single SMRT Cell.
Euan Ashley from Stanford University started with the premise that while current efforts in the field of genomics medicine address 30% of patient cases, there’s a need for new approaches to make sense of the remaining 70%. Toward that end, he said that accurately calling structural variants is a major need. In one translational research example, Ashley said that SMRT Sequencing with the Sequel System allowed his team to identify six potentially causative genes in an individual with complex and varied symptoms; one gene was associated with Carney syndrome, which was a match for the person’s physiology and was later…
Melissa Laird Smith discussed how the Icahn School of Medicine at Mount Sinai uses long-read sequencing for translational research. She gave several examples of targeted sequencing projects run on the Sequel System including CYP2D6, phased mutations of GLA in Fabry’s disease, structural variation breakpoint validation in glioblastoma, and full-length immune profiling of TCR sequences.
At AGBT 2017, Lars Paulin from the University of Helsinki presented this poster on whole genome sequencing of the virus responsible for progressive multifocal leukoencephalopathy, a rare and dangerous brain infection. His team used long amplicon analysis to resolve the whole virus genome from three patient samples, pooled them for SMRT Sequencing, and identified variants and rearrangements. This work represents the first time the viral genome was sequenced from patients.
In this podcast Sarah Tishkoff discusses what led her to study African genetics, and why she believes there is a need for more diversity in our genomic databases, with a particular emphasis on structural variation.
In this Webinar, we will give an introduction to Pacific Biosciences’ single molecule, real-time (SMRT) sequencing. After showing how the system works, we will discuss the main features of the technology with an emphasis on the difference between systematic error and random error and how SMRT sequencing produces better consensus accuracy than other systems. Following this, we will discuss several ground-breaking discoveries in medical science that were made possible by the longs reads and high accuracy of SMRT Sequencing.
In this AGBT 2017 talk, PacBio CSO Jonas Korlach provided a technology roadmap for the Sequel System, including plans the continue performance and throughput increases through early 2019. Per SMRT Cell throughput of the Sequel System is expected to double this year and again next year. Together with a new higher-capacity SMRT Cell expected to be released by the end of 2018, these improvements result in a ~30-fold increase or ~150 Gb / SMRT Cell allowing a real $1000 real de novo human genome assembly. Also discussed: Additional application protocol improvements, new chemistry and software updates, and a look at…
SMRT Sequencing is a DNA sequencing technology characterized by long read lengths and high consensus accuracy, regardless of the sequence complexity or GC content of the DNA sample. These characteristics can be harnessed to address medically relevant genes, mRNA transcripts, and other genomic features that are otherwise difficult or impossible to resolve. I will describe examples for such new clinical research in diverse areas, including full-length gene sequencing with allelic haplotype phasing, gene/pseudogene discrimination, sequencing extreme DNA contexts, high-resolution pharmacogenomics, biomarker discovery, structural variant resolution, full-length mRNA isoform cataloging, and direct methylation detection.