Next-generation sequencing (NGS) has enabled large-scale sequencing (of up to terrabases of sequences) within a couple of days1 and it has also lowered the cost of sequencing considerably.2 This time and cost saving can make sequencing the whole genome an attractive option for a researcher. However, even with the advances in NGS, whole genome sequencing (WGS) is still expensive, requires more sequencing yield and reagents,3 produces massive amounts of data that have to be scrutinized and interpreted, and generates the need to reconcile the associated uncertainties in data interpretations. As such, targeted sequencing of just the coding regions or specific genes or segments of chromosomes that are relevant to a particular disease has several advantages.
As a focused sequencing approach, targeted sequencing provides the ability to focus on specific disease-associated genes or other specific genes of interest. With this approach, the rest of the whole genome can be disregarded, simplifying downstream bioinformatics analysis and affording the ability to obtain greater depth of coverage.3 Depth of coverage (redundancy of coverage) matters as it can improve confidence in base calling for variant analysis.4 Target enrichment, an additive step to sample preparation, is needed for targeted sequencing and can be accomplished through a variety of techniques. In this article, we look at what target enrichment for NGS is, explore different target enrichment strategies, and understand why target enrichment is important for research in various disease areas.