Oxford Nanopore sequencing is a third generation sequencing technology using a pore protein to allow the DNA / RNA to pass through an artificial membrane. This allows the detection of electrons passing through the pore around the nucleic acid molecule, which can then be converted to a nucleotide sequence by real-time computational analysis.
The use of a pore protein (in the case of Nanopore sequencing, this is CsgG) also allows the detection of DNA modifications, including histones and other protein-DNA modifications. This is due to the changes in electron flow as modified nucleotides and histones pass through the pore protein. This can be used to identify transcriptionally active regions of the genome, such as euchromatic and heterochromatic regions.
Nanopore sequencing has longer read lengths compared to PacBio sequencing, of 2 Mb versus 50 kb. Nanopore also requires no library preparation, which can be like PacBio (although to improve accuracy, ‘SMRT-bell adaptors’ can be annealed to the dsDNA of interest in a preparation step).
The telomere-to-telomere project used Nanopore sequencing technology to enable a complete sequence of the human genome. This was due to the considerable read length enabling the resolution of repetitive regions. This enabled the complete construction of a consensus sequence, linking together discontinuous sequences from previous work (including the initial human genome project).
Nanopore sequencing has allowed a rapid shrinking of the technology, enabling it to be used in more locations, without the need to prepare the sample being sequenced. This enables quick sequencing, producing more data which can then be used in bioinformatics studies - and may be highly beneficial in genome-wide association studies (GWAS) enabling the identification of risk alleles involved in the development of genetic disorders.
Although Nanopore sequencing technology is promising, it does have lower accuracy compared to Illumina and Sanger sequencing techniques. But, the technology is under active development, and this is likely to be less of an issue in the future. Additionally, the flow of electrons can be captured as raw data, which can be re-analysed with improved software, potentially allowing the identification of other, (currently) unknown DNA modifications and interactions.
Nanopore sequencing is likely to lead to an explosion in the volume of DNA sequenced - leading to improved understanding of genomes and increasing the use of personalised medicine as well as understanding risk factors in the development of other conditions. This will likely result in improved clinical outcomes as the technology becomes prevalent in clinical practice in the coming years.