With the PacBio no-amplification (No-Amp) targeted sequencing method, you can now sequence through previously inaccessible regions of the genome to provide base-level resolution of disease-causing repeat expansions. By combining the CRISPR-Cas9 enrichment method with Single Molecule, Real-Time (SMRT) Sequencing on the Sequel Systems you are no longer limited by hard-to-amplify targets.
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.
Tetsuo Ashizawa, Director of the Neuroscience Research Program at Houston Methodist Research Institute, presents a novel amplification-free targeted enrichment method using CRISPR-Cas9 for the disease-causing repeat expansion in SCA10. Using long-read sequencing, he has been able to span multi-kilobase repetitive regions and identify interruption sequence motifs that correlate with alternative clinical phenotypes in individuals from varying ethnic backgrounds. Webinar registration required.
Targeted sequencing has proven to be an economical means of obtaining sequence information for one or more defined regions of a larger genome. However, most target enrichment methods are reliant upon some form of amplification. Amplification removes the epigenetic marks present in native DNA, and some genomic regions, such as those with extreme GC content and repetitive sequences, are recalcitrant to faithful amplification. Yet, a large number of genetic disorders are caused by expansions of repeat sequences. Furthermore, for some disorders, methylation status has been shown to be a key factor in the mechanism of disease. We have developed a…
Adam Ameur from the National Genomics Infrastructure at SciLifeLab presented this poster at AGBT 2017. In it, he details a validation study for the use of CRISPR/Cas9 to capture genomic targets without the use of amplification. Results from 12 Huntington’s patients indicate that this approach paired with SMRT Sequencing generates accurate repeat counts in the HTT gene.
In this ASHG 2017 presentation, Karen McFarland of the University of Florida presented research on spinocerebellar ataxia type 10 (SCA10), a progressive neurodegenerative disease caused by repeat expansions. She outlined efforts to sequence these repeat expansions including using CRISPR-Cas9 system coupled with SMRT Sequencing. McFarland shared findings from a study of a Parkinson’s disease patient and family that showed variations in expansion sequence can underlie distinct disease phenotypes.
Discover how the CRISPR-Cas9 system and PacBio long-read sequencing enable targeting of previously unsequencable regions of the genome, including long repeat expansions.
In this webinar, Jenny Ekholm and Paul Kotturi provide an overview of the PacBio No-Amp targeted sequencing application and its uses for targeting hard-to-amplify genes. This approach couples CRISPR-Cas9 with Single Molecule, Real Time (SMRT) Sequencing to enrich targets, without the need for PCR amplification, and generate complete sequence information with base-level resolution.
At AGBT 2020, Adam Ameur from Uppsala University discussed the use of long-read PacBio sequencing to detect off-target results from CRISPR/Cas9 gene editing studies. His team uses HiFi reads from the Sequel II System to perform whole genome sequencing and figure out exactly where guide RNAs bind. In one example using a human embryonic kidney cell line, they found 55 off-target sites for three guide RNAs. Ameur’s group has already generated preliminary data on results from editing living cells.
In this SMRT Leiden 2020 Online Virtual Event presentation Pedro Oliveira of Mount Sinai shares his research on Clostridioides – a leading cause of nosocomial-acquired diarrhea and colitis across the developed world. In this study, Oliveira and coworkers performed the first comprehensive DNA methylome analysis of 36 human C. difficile isolates from a hospital setting using SMRT Sequencing and comparative epigenomics.
In this SMRT Leiden 2020 Online Virtual Event presentation, Ida Hoijer of Uppsala University shares her research on developing a long-read sequencing-based method for detection of CRISPR-Cas9 off-target effects, along with a customized analysis pipeline. By applying an off-target sequencing (OTS) method on a human embryonic cell line, they detected 55 on- and off-target sites for three different gRNAs, including allele-specific off-targets. As the OTS approach finds off-targets that are difficult to predict using in silico or short-read based methods, it may become an important tool for genome editing.
Although PCR is a cost-effective way to enrich for genomic regions of interest for DNA sequencing, amplifying regions with extreme GC-content and long stretches of short tandem repeat (STR) sequences is often problematic and prone to sequence artifacts. This is especially true when developing multiplexed PCR assays for clinical applications such as carrier screening for multiple genes. The additional challenge is that all PCR primer pairs must be carefully selected to be compatible based on amplicon size and PCR conditions. Due to these experimental design constraints, a single tube with a high number of multiplexed PCR amplicons is difficult to…
In this webinar, Adam Ameur of SciLifeLab at Uppsala University shares how he uses Single Molecule, Real-Time (SMRT) Sequencing applications for medical diagnostics and human genetics research, including sequencing of single genes and de novo assembly of human genomes as well as a new method for detection of CRISPR-Cas9 off-targets.
Targeted sequencing of genomic DNA requires an enrichment method to generate detectable amounts of sequencing products. Genomic regions with extreme composition bias and repetitive sequences can pose a significant enrichment challenge. Many genetic diseases caused by repeat element expansions are representative of these challenging enrichment targets. PCR amplification, used either alone or in combination with a hybridization capture method, is a common approach for target enrichment. While PCR amplification can be used successfully with genomic regions of moderate to high complexity, it is the low-complexity regions and regions containing repetitive elements sometimes of indeterminate lengths due to repeat expansions that…