Whole genome versus whole exome — the coverage, cost and discovery trade-offs that should drive the choice.
Whole genome sequencing (WGS) and whole exome sequencing (WES) both read the genome, but they answer different questions at different price points. Choosing well early saves both budget and re-sequencing later.
Whole exome: focused and economical
WES targets the roughly 1-2% of the genome that codes for proteins, where most known disease-causing variants sit. Capturing only the exome means deeper coverage of those regions for a fraction of the cost — ideal for large cohorts focused on coding variation.
Whole genome: complete and unbiased
WGS reads coding and non-coding regions alike, with uniform coverage and no capture bias. It is the method of choice for structural variants, regulatory regions and discovery work where you do not yet know where to look.
Use WES to interrogate the coding genome cheaply; use WGS when the answer might lie anywhere.
- WES — coding variants, large cohorts, lower cost
- WGS — structural and non-coding variation, no capture bias
- Both — match coverage and depth to the study design