Targeted resequencing technologies use the power of next-generation sequencing technologies to combine the capacity to identify, partition, index, and target specific genomic regions.
Targeted resequencing provides in-depth coverage and high sensitivity and specificity, resulting in high-quality data at a price which is cost-effective. For that reason, targeted resequencing has many advantages over other next generation sequencing technologies like whole genome sequencing for a wide range of bioinformatic applications that require high-throughput deep sequencing of broad gene sets from hundreds or thousands of samples.
The use of targeted resequencing technologies has revolutionized the study of human genetic variation by allowing the analysis of coding regions, non-coding regions, and regulatory elements. This approach has been applied to the discovery of rare variants associated with complex diseases. The use of targeted resequencing to study human genetic variation has also been used to understand and identify the genetic basis of somatic mutations.
However, deciding whether to use PCR, Sanger sequencing, targeted resequencing, or wider next generation sequencing (NGS) techniques like exome sequencing or Whole Genome Sequencing is a complex process that involves several variables.
Variables might include things like the number of samples, the total amount of sequence in the targeted genomic regions, sequencing costs, and ultimately, the overall goals of the research study.
When the amount of target regions is limited (1–20 target loci), and when the aims of the study are identifying or screening known targets or genetic variants, Sanger sequencing and PCR are typically good choices. At the other end of the spectrum, exome sequencing and Whole Genome Sequencing (WGS) are excellent approaches for sequencing the human genome as they provide comprehensive genetic analysis and variant discovery.
Targeted Next Generation Resequencing however provides a great balance of these tools, allowing both screening and variant discovery research designs. A cost-effective approach, targeted resequencing can sequence tens to thousands of genes with a high number of samples. Its ability to sequence multiple genes across multiple samples simultaneously saves time and resources when compared to other traditional sequencing methods
Furthermore, targeted Next Generation Sequencing sampling techniques minimizes genomic DNA sample loss by lowering DNA input—an issue of concern for applications such as forensics DNA testing, single-cell extracts, and cancer biopsy samples.
One of targeted sequencing’s most significant strengths is its ability to sequence a specific genomic region of interest at substantially higher sequencing coverage levels than Whole Genome Sequencing or Sanger sequencing. Whole Genome Sequencing is usually performed at 30-75x sequencing coverage, whilst targeted sequencing sequences at depths of 5000x or higher. This deeper sequencing level ultimately translates into higher sensitivity, enabling variant detection at lower frequencies.
Targeted resequencing is becoming more popular among clinical and translational researchers. This is due to the fact that clinical or translational studies demand tests that are not only precise, but also quick and cost-effective. Targeted DNA sequencing effectively addresses both several of these challenges. Recent studies comparing Sanger sequencing and targeted resequencing techniques when analysing tumor samples revealed that targeted resequencing was faster, required significantly less input material and was more cost-effective than Sanger sequencing.
PCR, Sanger sequencing, and targeted resequencing provide varying degrees of information depending on the study objectives. PCR can identify whether a variant exists, but not at single-base resolution. Sanger sequencing is cost-effective for identifying particular variations but only at single-base precision for a limited number of genes or target regions. In contrast, in a single experiment targeted resequencing can find variants across thousands of target DNA regions, down to single-base resolution. Further, the higher scale of sequence analysis and targeted sequence capture methods increases the chance of finding novel variants.
Undertake your targeted sequencing using our next generation sequencing platform. Our workflow moves through stages including: