Whole-Exome Sequencing

Overview:

Whole Exome Sequencing focuses on sequencing the 1–2% of the genome that contains protein-coding regions (exons), where most known disease-causing variants occur. WES typically uses short-read Illumina platforms to obtain high coverage (commonly 80-150x) allowing confident detection of single nucleotide variants (SNVs) and small insertions/deletions in coding regions. Sample types include genomic DNA from blood, saliva, tissues, or cell lines, with input requirements ranging from 10 ng to >100 ng depending on the library kit (PCR-free vs PCR-based). Modern capture kits ensure high uniformity, improved GC coverage, and reduced off-target reads. WES is widely applied for Mendelian disease diagnostics, cancer gene panel expansion, discovery of coding mutations in research cohorts, pharmacogenomics, and functional variant studies. It does not capture regulatory or non-coding regions, and structural variant detection is limited compared with WGS, but provides a cost-effective, high-resolution view of the exome for both clinical and research applications.

Workflow:

DNA extraction, library preparation, hybridization-based target capture or amplicon enrichment, sequencing.