Whole Exome Sequencing (WES), explained clearly.
The exome is the 1–2% of your DNA that makes proteins — and it holds about 85% of all known disease-causing variants. That's why WES is the gold-standard general genetic test.
- ~20,000 protein-coding genes
- Detects 85% of known disease variants
- Faster and lower cost than WGS
- The technology NAWA uses
Genome vs exome vs gene — the three scales.
Genome
All 3 billion DNA base pairs. Includes coding regions (exons), non-coding regions (introns), and regulatory sequences. WGS reads all of it.
Exome
Only the protein-coding regions — the exons of all 20,000 genes. ~1–2% of the genome, but where most disease-causing variants live.
Gene
A single stretch of DNA that codes for one protein. A gene panel targets a specific set of genes; WES targets all of them at once.
WES vs WGS vs gene panels.
WGS covers more genomic territory but at 3–5× the cost, longer turnaround, and marginal clinical yield over WES for premarital use. NAWA offers WGS on request when clinically indicated.
Clinical-grade sequencing, three-physician review.
100x+ coverage
Every reported region is sequenced with at least 100 independent reads. This is the depth required for confident clinical variant calls.
ACMG classification
Variants are classified using American College of Medical Genetics standards — pathogenic, likely pathogenic, VUS, likely benign, benign.
3-specialist review
Every reported variant is independently reviewed by three specialist physicians. No unreviewed automated calls reach the final report.
Common questions about WES.
What is whole exome sequencing?
Whole exome sequencing (WES) reads all protein-coding regions of the genome — about 20,000 genes. These regions (the 'exome') make up roughly 1–2% of the total DNA but contain about 85% of known disease-causing variants, making WES the highest-yield general test for inherited disease.
How is WES different from WGS?
WGS (whole genome sequencing) reads the entire genome, including non-coding regions. WES focuses only on the coding regions. WES is faster, less expensive, and yields the majority of clinically relevant findings — WGS is used when non-coding variants are specifically suspected.
How is WES different from a gene panel?
A gene panel tests a fixed set of pre-selected genes (usually 50–500). WES tests all ~20,000 genes without preselection — so it can detect rare or unexpected variants that panels miss.
What can WES detect?
Single-nucleotide variants and small insertions/deletions in coding regions and adjacent splice sites. Most known Mendelian (single-gene) inherited diseases fall into this category — including nearly all conditions relevant to premarital carrier screening.
What can WES not detect?
Large structural variants (big duplications or deletions), deep intronic variants far from coding regions, trinucleotide repeat expansions (like Huntington's or fragile X), and mitochondrial DNA (unless a mitochondrial panel is added). For these, targeted tests are used.
How accurate is WES?
Modern clinical-grade WES achieves >99% accuracy for single-nucleotide variants in well-covered coding regions. NAWA uses NGS platforms with minimum 100x coverage across the medical exome and every reported variant is reviewed by three specialist physicians before results are released.