May 16, 2022  |  AAV

Application Brochure AAV Sequencing with HiFi Reads

With Single Molecule, Real-Time (SMRT®) sequencing on the Sequel® IIe systems, you can sequence AAV
genome populations to identify truncation, mutation, and host integration events. The AAV workflow from
PacBio® accommodates both scAAV and ssAAV constructs with easy on-instrument HiFi read generation

December 20, 2021  |  

Germline mosaicism of a missense variant in KCNC2 in a multiplex family with autism and epilepsy

Currently, protein-coding de novo variants and large copy number variants have been identified as important for ∼30% of individuals with autism. One approach to identify relevant variation in individuals who lack these types of events is by utilizing newer genomic technologies. In this study, highly accurate PacBio HiFi long-read sequencing was applied to a family with autism, treatment-refractory epilepsy, cognitive impairment, and mild dysmorphic features (two affected female full siblings, parents, and one unaffected sibling) with no known clinical variant. From our long-read sequencing data, a de novo missense variant in the KCNC2 gene (encodes Kv3.2 protein) was identified in both affected children. This variant was phased to the paternal chromosome of origin and is likely a germline mosaic. In silico assessment of the variant revealed it was in the top 0.05% of all conserved bases in the genome, and was predicted damaging by Polyphen2, MutationTaster, and SIFT. It was not present in any controls from public genome databases nor in a joint-call set we generated across 49 individuals with publicly available PacBio HiFi data. This specific missense mutation (Val473Ala) has been shown in both an ortholog and paralog of Kv3.2 to accelerate current decay, shift the voltage dependence of activation, and prevent the channel from entering a long-lasting open state. Seven additional missense mutations have been identified in other individuals with neurodevelopmental disorders (p = 1.03 × 10−5). KCNC2 is most highly expressed in the brain; in particular, in the thalamus and is enriched in GABAergic neurons. Long-read sequencing was useful in discovering the relevant variant in this family with autism that had remained a mystery for several years and will potentially have great benefits in the clinic once it is widely available.

August 19, 2021  |  AAV

Application Brochure: Gene editing validation with HiFi reads

With highly accurate long reads (HiFi reads) from the Sequel IIe System, powered by Single Molecule, Real-Time (SMRT) Sequencing technology, you can efficiently and cost effectively validate gene editing techniques including adeno-associated virus (AAV) and CRISPR-Cas9 approaches.

June 1, 2021  |  

Beyond Contiguity: Evaluating the accuracy of de novo genome assemblies

HiFi reads (>99% accurate, 15-20 kb) from the PacBio Sequel II System consistently provide complete and contiguous genome assemblies. In addition to completeness and contiguity, accuracy is of critical importance, as assembly errors complicate downstream analysis, particularly by disrupting gene frames. Metrics used to assess assembly accuracy include: 1) in-frame gene count, 2) kmer consistency, and 3) concordance to a benchmark, where discordances are interpreted as assembly errors. Genome in a Bottle (GIAB) provides a benchmark for the human genome with estimated accuracy of 99.9999% (Q60). Concordance for human HiFi assemblies exceeds Q50, which provides excellent genomes for downstream analysis, but presents a challenge that any new benchmark must significantly exceed Q50 or the discordance will represent the error rate of the benchmark. To establish benchmarks for Oryza sativa and Drosophila melanogaster, we collected draft references, Illumina short reads, and PacBio HiFi reads. By species, the benchmark was defined as regions of normal coverage that are not within 5 bp of a small variant or 50 bp of a structural variant. For both species, the benchmark regions span around 60% of the genome and HiFi assemblies achieve Q50 accuracy, which is notably more accurate than assemblies with other technologies and meets typical standards for a finished, reference-grade assembly. Here we present a protocol to generate benchmarks for any sample that rival the GIAB benchmark in accuracy. These benchmarks allow the comparison and improvement of genome assemblies and highlight the superior accuracy of assemblies generated with PacBio HiFi reads.

June 29, 2015  |  

Human Genome Sequenced without Cloning Steps

A collaboration of scientists led by researchers from Icahn School of Medicine at Mt. Sinai has created a comprehensive analysis of a diploid human genome using two complementary single DNA molecule methods for sequencing and genome mapping, and without the need for any DNA amplification techniques.

August 25, 2014  |  

Updates from the Genome in a Bottle Consortium

Justin Zook of the National Institute of Standards and Technology (NIST) discussed the progress and future goals of the Genome in a Bottle project, which aims to create near-perfectly characterized human genome sequences for use as reference standards.

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