What is third-generation sequencing?

DNA sequencing has made remarkable progress since the discovery of the DNA double-helix. Next-generation sequencing (NGS) revolutionized the field but has limitations like short read lengths. Third-generation sequencing (TGS) overcomes this challenge by providing longer reads for improved genome analysisIt allow clinicians and researchers to learn about differences and changes in an individual's genetic makeup, leading to discovering the role that genetics plays in disease and treatment..

Third-generation sequencing

Third-generation sequencing (TGS), also known as long-read sequencing, is a category of DNA sequencing techniques that are currently undergoing significant advancements.

Applications

Here are a few of the applications of third-generation sequencing (TGS).

• Third-generation sequencing technologies, such as PacBio SMRT sequencing and ONT nanopore sequencing, have significant implications for genome science and biology.

• TGS simplifies genome assembly and enhances the accuracy of genome annotation.Genome annotation is the process of identifying and labeling the functional elements, such as genes and regulatory regions, within a genome sequence.

• TGS outperforms existing methods, even at low sequencing coverage, for applications that tolerate error rates, such as structural variant calling.

• TGS is valuable in cancer research for identifying genomic alterations and mutations contributing to cancer development and progression.

• TGS enables the study of epigenetic modifications on native DNA, providing insights into gene expression regulation.

Advantages

The advancements in third-generation sequencing (TGS) have revolutionized genome science and biology, with critical implications for various fields of research and applications. Here are the key points.

• TGS technologies produce reads that are tens of kilobases long, simplifying genome assembly and improving genome annotation accuracy.

• TGS outperforms existing methods, even with low sequencing coverage, particularly in applications tolerant of error rates like structural variant calling.

• TGS enhances the diagnostic accuracy of genetic diseases at the molecular level, aiding in precision medicine and personalized treatment.

• TGS paves the way for in-depth basic research, unraveling complex genomic architectures, understanding gene regulation, and studying the interplay of genetics in biological processes.

• TGS holds promise for advancing therapies by enabling a comprehensive understanding of disease mechanisms, identifying therapeutic targets, and monitoring treatment responses.

• TGS offers new avenues for studying microbial communities, metagenomicsMetagenomics is the study of genetic material collected from environmental samples to understand the composition and function of microbial communities., and environmental DNA, contributing to understanding biodiversity and ecological systems.

Limitations

While third-generation sequencing technologies have brought significant improvements to DNA sequencing, they are not without limitations. Here are some of the limitations associated with third-generation sequencing.

• High error rates: TGS technologies have higher error rates, affecting genome assembly and data analysis.

• Active development: TGS is still evolving, with ongoing efforts to improve and overcome current limitations.

• Costly sequencing: TGS can be expensive, limiting its accessibility for researchers with limited funding.

Key technologies and platforms

Key technologies and platforms for third-generation sequencing include.

• Single-molecule real-time (SMRT) sequencing: PacBio's zero-mode waveguides enable long reads without PCR amplification.

• Nanopore sequencing: ONT uses protein nanopores for real-time detection of DNA.

• Long reads with no amplification: TGS technologies work by sequencing a single molecule, so it provides long reads without the need for repeated amplification.

• Direct detection of epigenetic modifications on native DNA: TGS has been used to study epigeneticIt is the study of how your behaviors and environment can cause changes that affect the way your genes work. modifications on native DNA, which can provide a window into the regulation of gene expression.

• Portability and sequencing speed: TGS has the potential for portability and faster sequencing.

Conclusion

TGS is a group of DNA sequencing methods that can make much longer reads than NGS. This is very important for both genome science and biology in general. TGS technologies are being actively worked on, and it is expected that the high error rates will get better.