Introduction
Next generation sequencing (NGS) is now in routine use for a broad range of research and clinical applications. The rapid rate of adoption has been facilitated by falling reagent costs, benchtop instruments, improved chemistries and improved data analysis solutions. However, the cost and complexity of data analysis still remain significant hurdles — particularly for whole genome sequencing. In the majority of cases, targeted approaches, such as custom NGS panels, are more cost-effective and generate significantly less, but equally meaningful data in a much shorter timescale.
Targeted sequencing requires an initial sequence enrichment step, which, if poorly designed, can be a source of bias and error in the downstream sequencing assay1. This article discusses the main strategies employed to optimise the enrichment step, depending on the type of assay chosen.
Which enrichment assay?
Two broad categories of enrichment assays exist: amplicon (PCR) and hybridisation (Figure 1). As a very general rule, hybridisation-based assays, when designed well, offer superior performance2.