Types of DNA Sequencing Technologies

Depending on the target, Next-Generation Sequencing (NGS) analysis can range from a few genes to an entire genome. The sequence of DNA bases across the genome and exome is determined by Whole-Genome Sequencing (WGS) and Whole-Exome Sequencing (WES), respectively.

FREMONT, CA: Some techniques have been extinct since the advent of sequencing in the 1970s. In contrast, others have advanced to become the methods of choice for many researchers trying to understand genetic variation today.

Capillary electrophoresis and fragment analysis

Instruments that use Capillary Electrophoresis (CE) can perform both Sanger sequencing and fragment analysis. DNA fragments are fluorescently numbered, separated by CE, and sized by reference to an internal norm of fragment analysis. At the same time, DNA sequencing by CE is used to identify the precise base sequence of a particular fragment or gene segment. This technique can also offer sizing, relative quantitation, and genotyping data for fluorescently labeled DNA fragments produced by PCR employing primers designed for a specific DNA target. DNA fragment analysis can be used for anything from cell line authentication to aneuploidy detection. Although sequencing techniques may also be employed for these applications, researchers prefer fragment analysis because it is more cost-effective and has a quicker turnaround time.

Next-Generation Sequencing (NGS)

While Sanger sequencing has seen numerous advancements over the years, new high-throughput techniques known as next-generation sequencing (NGS) technologies have also emerged. NGS is carried out in a massively parallel manner. Depending on the target, NGS analysis can range from a few genes to an entire genome. The sequence of DNA bases across the genome and exome is determined by Whole-Genome Sequencing (WGS) and Whole-Exome Sequencing (WES), respectively.

To determine differences and gene expression levels across the entire transcriptome, whole-transcriptome sequencing provides sequence information about coding and multiple noncoding types of RNA. Targeted sequencing focuses on a limited number of genes or regions of interest. Targeted sequencing is well suited for both translational and clinical research applications due to its fast turnaround time, low cost, low sample input requirement, and relative ease of interpretation. Sanger sequencing is often used to validate variants discovered using NGS. Sanger sequencing, fragment analysis, and NGS allow a slew of cutting-edge applications that advance the understanding of genomes.