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.
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.
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.
Background: Genotypic testing of chronic viral infections is an important part of patient therapy and requires assays capable of detecting the entire spectrum of viral mutations. Single Molecule, Real-Time (SMRT) sequencing offers several advantages to other sequencing technologies, including superior resolution of mixed populations and long read lengths capable of spanning entire viral protein coding regions. We examined detection sensitivity of SMRT sequencing using a mixture of HIV-1 RT gene coding regions containing single NNRTI mutations. Methodology: SMRTbell templates were prepared from PCR products generated from a prospective reference material being developed by BC Center of Excellence for HIV/AIDS, and…
A large number of distinct HIV-1 genomes can be present in a single clinical sample from a patient chronically infected with HIV-1. We examined samples containing complex mixtures of near-full-length HIV-1 genomes. Single molecules were sequenced as near-full-length (9.6 kb) amplicons directly from PCR products without shearing. Mathematical analysis techniques deconvolved the complex mixture of reads into estimates of distinct near-full-length viral genomes with their relative abundances. We correctly estimated the originating genomes to single-base resolution along with their relative abundances for mixtures where the truth was known exactly by independent sequencing methods. Correct estimates were made even when genomes…
Background: The HIV-1 proviral reservoir is incredibly stable, even while undergoing antiretroviral therapy, and is seen as the major barrier to HIV-1 eradication. Identifying and comprehensively characterizing this reservoir will be critical to achieving an HIV cure. Historically, this has been a tedious and labor intensive process, requiring high-replicate single-genome amplification reactions, or overlapping amplicons that are then reconstructed into full-length genomes by algorithmic imputation. Here, we present a deep sequencing and analysis method able to determine the exact identity and relative abundances of near-full-length HIV genomes from samples containing mixtures of genomes without shearing or complex bioinformatic reconstruction. Methods:…
The sensitivity, speed, and reduced cost associated with Next-Generation Sequencing (NGS) technologies have made them indispensable for the molecular profiling of cancer samples. For effective use, it is critical that the NGS methods used are not only robust but can also accurately detect low frequency somatic mutations. Single Molecule, Real-Time (SMRT) Sequencing offers several advantages, including the ability to sequence single molecules with very high accuracy (>QV40) using the circular consensus sequencing (CCS) approach. The availability of genetically defined, human genomic reference standards provides an industry standard for the development and quality control of molecular assays. Here we characterize SMRT…
Scientists who require confident resolution of heterogeneous populations across complex regions have been unable to transition to short-read sequencing methods. They continue to depend on Sanger sequencing despite its cost and time inefficiencies. Here we present a new redesigned algorithm that allows the generation of circular consensus sequences (CCS) from individual SMRT Sequencing reads. With this new algorithm, dubbed CCS2, it is possible to reach high quality across longer insert lengths at a lower cost and higher throughput than Sanger sequencing. We applied CCS2 to the characterization of the HIV-1 K103N drug-resistance associated mutation in both clonal and patient samples.…
Next-Generation Sequencing (NGS) technologies allow for molecular profiling of cancer samples with high sensitivity and speed at reduced cost. For efficient profiling of cancer samples, it is important that the NGS methods used are not only robust, but capable of accurately detecting low-frequency somatic mutations. Single Molecule, Real-Time (SMRT) Sequencing offers several advantages, including the ability to sequence single molecules with very high accuracy (>QV40) using the circular consensus sequencing (CCS) approach. The availability of genetically defined, human genomic reference standards provides an industry standard for the development and quality control of molecular assays for studying cancer variants. Here we…
Detection of somatic mutations, especially in heterogeneous tumor samples where variants may be present at a low level, is challenging. Single Molecule, Real-Time (SMRT) Sequencing is ideal for minor variant detection because of its ability to sequence single molecules with very high accuracy (>QV40) using the circular consensus sequencing (CCS) approach.
Targeted sequencing with Sanger as well as short read based high throughput sequencing methods is standard practice in clinical genetic testing. However, many applications beyond SNP detection have remained somewhat obstructed due to technological challenges. With the advent of long reads and high consensus accuracy, SMRT Sequencing overcomes many of the technical hurdles faced by Sanger and NGS approaches, opening a broad range of untapped clinical sequencing opportunities. Flexible multiplexing options, highly adaptable sample preparation method and newly improved two well-developed analysis methods that generate highly-accurate sequencing results, make SMRT Sequencing an adept method for clinical grade targeted sequencing. The…