What is Whole Exome Sequencing?
Whole Exome Sequencing (WES) captures and sequences the protein-coding regions of the genome — the exome — in a single, comprehensive test. Although exons account for only 1–2% of the human genome, they are estimated to contain the majority of known disease-causing mutations, making WES one of the most efficient tools for identifying the genetic cause of a suspected inherited condition. Unlike single-gene or panel testing, WES is not limited to a predefined gene list, and the underlying data can be re-analyzed as new gene-disease associations are discovered.
Broader Than Panel Testing
Captures nearly all protein-coding genes at once, rather than a predefined list — useful when the clinical picture doesn't point to a single gene.
More Targeted Than WGS
Focuses sequencing depth on the coding regions most likely to explain a phenotype, at a lower cost than whole genome sequencing.
Re-analyzable Over Time
Exome data can be reviewed again as new gene-disease associations are published, without needing to resequence the patient.
Who Should Consider WES?
Rare & Undiagnosed Disorders
Patients with a suspected genetic condition not identified through targeted panel testing.
Consanguineous Families
Families with parental consanguinity, where autosomal recessive conditions are more likely.
Population & Translational Research
Research studies investigating rare variants associated with complex traits.
Tumor Research
Investigating somatic and germline variants relevant to tumor biology, for translational research.
How the Test Works
| Sample Type | Peripheral blood (EDTA tube) |
|---|---|
| Exome Enrichment | Twist Exome Panel V2 Kit |
| Sequencing Platform | Illumina NovaSeq X Plus |
| Reference Genome | GRCh38 / hg38 |
| Variant Interpretation | ACMG/AMP guidelines, with internal review by a genetics specialist |
| CNV Detection | Called from exome read-depth metrics, with orthogonal review for clinically relevant events |
| Typical Coverage | > 100× average depth, with ≥97% of target bases covered at ≥30× in a representative run |
Analysis Levels
Raw sequencing data moves through five cumulative levels of analysis before a clinical report is generated.
Quality Control & Alignment
Raw sequencing reads are quality-checked and aligned to the GRCh38/hg38 reference genome.
Variant Calling
Single nucleotide variants (SNVs) and small insertions/deletions (indels) are identified across the exome.
Annotation & ACMG Classification
Variants are annotated and classified per ACMG/AMP guidelines (Class 1: Pathogenic → Class 5: Benign), with internal review by a molecular genetics specialist.
Copy Number Variant (CNV) Analysis
Exome read-depth metrics are used to call copy number variants, with orthogonal review for clinically relevant events.
Clinical Correlation & Reporting
Findings are correlated with the patient's clinical indications, HPO terms, and family history — including consanguinity — to produce primary, carrier, and incidental findings with clinical interpretation.
What's Included in Your Clinical Report
Primary SNV Findings
The single-nucleotide variant(s) most likely to explain the patient's clinical presentation, with transcript, zygosity, and clinical interpretation.
CNV Findings
Clinically relevant copy number variants — deletions or duplications — detected from exome read-depth data.
Carrier Findings
Autosomal recessive carrier status for conditions unrelated to the primary indication, relevant for family planning.
Incidental Findings
Medically actionable findings per ACMG Secondary Findings v3.3, reported regardless of the original test indication.
Interpretation & Recommendations
Clear next steps — confirmatory testing, parental/family studies, and genetic counseling referrals.
Sequencing Statistics
Average coverage depth and percentage of target bases covered at clinically relevant thresholds.
See a Real Report Structure
Download a sample WES clinical report to see exactly how findings, classifications, and recommendations are presented.
Download Sample ReportFrequently Asked Questions
What is the difference between WES and WGS?
Whole Exome Sequencing (WES) sequences only the protein-coding regions of the genome (~1–2%), which are estimated to harbor the majority of known disease-causing mutations. Whole Genome Sequencing (WGS) sequences the entire genome, including non-coding regions, generating far more data to interpret. WES offers a cost-effective, high-depth alternative when the coding regions are the primary focus.
What sample types are accepted?
Peripheral blood collected in an EDTA tube is the standard sample type for WES.
What is the turnaround time?
Turnaround time depends on case complexity and the analysis level requested. Contact our team for current processing times.
What are incidental findings?
Incidental findings are medically actionable results unrelated to the original reason for testing, reported according to ACMG Secondary Findings (SF) v3.3 guidelines — for example, a pathogenic variant in a cardiac gene found while investigating an unrelated condition.
Can WES detect all types of genetic variants?
No single test detects everything. WES reliably detects SNVs and small indels in coding regions, and can detect some CNVs from read-depth data. It does not reliably detect balanced rearrangements, repeat expansions, deep intronic variants, or low-level mosaicism — these require complementary testing.
Is trio or family testing available?
Yes. Analyzing samples from both parents alongside the patient (trio analysis) can help determine whether a variant is inherited or arose de novo, and is especially valuable in consanguineous families.
Do I need genetic counseling before or after testing?
Genetic counseling is recommended both before testing, to set expectations about possible results, and after testing, to interpret findings and discuss implications for the patient and family.