Whole Exome Sequencing (WES)

What is Whole Exome Sequencing?

Whole Exome Sequencing (WES) is a highly efficient genetic test that reads the exome the specific 1–2% of your DNA that contains the instructions for making proteins.

While the exome makes up only a tiny fraction of your total genome, it is the most biologically active part. In fact, it is estimated that 85% of known disease-causing variants are located within this small region.

This makes WES a powerful "middle ground" in genetic testing: it captures the vast majority of medically relevant genetic changes without the higher cost and data complexity of reading the entire genome.

Who is WES for?

WES is widely used when doctors suspect a genetic condition but do not know exactly which gene is involved. It is an ideal choice if:

• You have complex symptoms: If you have an undiagnosed condition or rare disease, WES casts a wide net to find the cause.
• You want broad proactive screening: For healthy individuals who want to know more than standard panels can tell them, WES provides a comprehensive look at ~20,000 genes.
• You are planning a family: WES can serve as an expanded form of Carrier Screening, checking for hundreds of recessive conditions at once.

Jeen’s team can advise if WES is the right fit, or if a more targeted Genetic Test would suit your needs better.

What does WES test for?

This test sequences all of your protein-coding genes (approximately 20,000 genes). It looks for variants that could cause disease or increase health risks.

Because it covers the whole exome, WES allows us to screen for a wide variety of conditions in one go, including:

• Developmental Disorders: Identifying causes of delayed development or intellectual disability.
• Rare Diseases: Pinpointing conditions that are difficult to diagnose clinically.
• Cancer Risks: Detecting variants in known cancer genes (like BRCA1/2 and PALB2) just as effectively as specific Cancer Panels.

WES Speed and Efficiency

Since WES examines just the exome, labs can often analyse the data more quickly than with Whole Genome Sequencing. This is why NHS programmes often use WES for rapid diagnoses in critically ill children, per Genomics Education Programme. Jeen leverages this efficiency to get you reliable results faster.

Why does WES matter?

WES offers a balance of depth and discovery. Because it includes almost all genes, it can find unexpected results that targeted tests might miss.

• Uncovering the Unknown: By looking at all exons, WES can uncover rare or novel disease variants that would not appear on a standard "panel" test.
• Informing Treatment: Results can guide medical management, medication choices, or lifestyle changes.

Important Note: WES does not see variants in the non-coding DNA (the 98% of DNA outside of genes). For most inherited disorders known today, this is not an issue. However, if your WES result is inconclusive, Whole Genome Sequencing (WGS) might be considered as a final step.

Limitations of Whole Exome Sequencing (WES)

WES ignores the 98% of DNA that doesn't code for proteins (introns and regulatory regions). While rare, some disease-causing variants do hide in these areas. Sometimes the chemical process used to "capture" the exome misses small sections of certain genes, meaning coverage isn't always 100% uniform.

How does the testing process work?

1. Order and sample collection: Book your WES test on the Jeen website. We ship an easy-to-use at-home saliva kit to you.
2. Lab sequencing: You return the sample, and our accredited lab extracts the DNA. We then sequence all exons in your genome with high depth.
3. Data analysis: Our bioinformaticians compare your exome against a reference to flag any variants that match known disease-related changes.
4. Reporting: We generate a report highlighting important findings (e.g., pathogenic variants) and explaining them in plain English.
5. Genetic Counselling: One of our Genetic Counsellors will review the report with you by phone or video. They help you understand exactly what the findings mean for your future.

WES results usually take around 3–4 weeks after the lab receives your sample.

Next Steps after WES result

After getting your results, your genetic counsellor will meet with you to explain them.

• If a variant is found: We will discuss medical follow-up, potential treatments, or implications for family members.
• If nothing is found: We will explain the reassurance this offers and discuss general health recommendations.

Jeen’s WES service empowers you with detailed genetic information: you gain clarity on potential inherited risks and the reassurance that we have thoroughly analysed your exome.