Whole Exome Sequencing (WES) is a powerful genetic testing method that focuses on sequencing all the protein-coding regions of the genome, known as exons. These regions make up only about 1–2% of the genome but contain around 85% of known disease-causing mutations.
How It’s Done:
- Sample Collection: A blood or saliva sample is collected.
- DNA Extraction: DNA is isolated from the sample.
- Library Preparation: DNA is fragmented and tagged with adapters.
- Exome Capture: Special probes enrich the exonic regions.
- Sequencing: High-throughput sequencing machines read the DNA.
- Data Analysis: Bioinformatics tools identify genetic variants.
- Interpretation: Geneticists analyze the data to find disease-related mutations.
Purpose and Usage:
WES is primarily used to diagnose rare or undiagnosed genetic disorders, especially when symptoms are complex or affect multiple systems. It is also used in cancer genomics to identify mutations in tumors, in pharmacogenomics to tailor drug treatments, and in reproductive planning to detect carrier status for inherited conditions.
Applications:
- Clinical Diagnostics: For patients with unexplained symptoms or developmental delays.
- Cancer Research: Identifying somatic mutations in tumors.
- Genetic Counseling: Helping families understand inherited conditions.
- Personalized Medicine: Tailoring treatments based on genetic makeup.
Understanding WES:
WES provides a comprehensive view of the coding regions of the genome, offering insights into the genetic basis of disease. However, it does not detect mutations in non-coding regions or large structural changes. Interpretation requires expertise, especially for variants of uncertain significance.