Molecular Genetic Whole Exome Sequencing WES - NGS
Also Known As
Test Parameters Included
- Exonic Region Sequencing Coverage (target: ~1-2 Mb coding genome, ≥20x mean depth)
- Pathologist Molecular Genetics Remark - variant classification (pathogenic / likely pathogenic / VUS) mapped against ClinVar, OMIM, and ACMG guidelines
Department
Methodology
NGS (Next-Generation Sequencing) is the foundational technology for Whole Exome Sequencing (WES). WES is a powerful and high-throughput molecular diagnostic technique that involves sequencing the protein-coding regions of all genes in the human genome. While the human genome is vast, the exome (the collection of all exons) constitutes only about 1-2% of the genome but contains approximately 85% of known disease-causing mutations. For WES, DNA is extracted and then enriched for exonic regions. These enriched fragments are then massively sequenced in parallel using NGS platforms. The resulting sequence data is aligned to a reference genome, and sophisticated bioinformatics pipelines are used to identify genetic variants (SNPs, indels, copy number variations) within the exome. This comprehensive approach allows for the detection of known and novel pathogenic mutations across thousands of genes simultaneously, making it an invaluable tool for diagnosing a wide range of genetic disorders, especially when the clinical presentation is atypical or previously targeted gene testing has been inconclusive.
Sample Required
(A sample of whole blood collected in an EDTA vacutainer is required for this test. EDTA acts as an anticoagulant to preserve the blood sample for high-quality DNA extraction.)
Preparation
* No Fasting Required: Fasting is not necessary for this blood sample collection.
* No Special Timing: Blood can be drawn at any time of day.
* Comprehensive Clinical Information: Providing detailed clinical information, including symptoms, family history (pedigree), results of previous genetic tests, and imaging studies, is absolutely crucial for accurate interpretation of WES results. This information helps the clinical geneticists and bioinformaticians prioritize and interpret identified variants.
* Genetic Counseling: It is highly recommended to have pre-test genetic counseling with a qualified genetic counselor. They can explain the potential benefits, limitations (e.g., possibility of finding variants of unknown significance or incidental findings), and implications of WES, as well as guide the consent process. * Parental Samples (for Trio WES): For optimal diagnostic yield, especially in pediatric cases or complex presentations, samples from both biological parents (trio WES) are often requested. This allows for comparative analysis to identify inherited or de novo mutations.
Schedule Report
30 to 35 Days
Emergency Report
Yes
Frequently Asked Questions
Is fasting required for Whole Exome Sequencing?
No, fasting is not required. A simple whole blood sample in EDTA is sufficient for DNA extraction.
What is the typical turnaround time for WES results?
Report turnaround is approximately 15-21 working days, as bioinformatics analysis and variant interpretation are complex multi-step processes.
What sample is collected for WES?
Whole blood in EDTA (purple-top) vacutainer. Minimum 3 mL is recommended for adequate genomic DNA yield.
Can medications affect WES results?
No, medications do not alter your DNA sequence. WES detects inherited or de novo genetic variants regardless of current drug intake.
What do VUS or variant of uncertain significance results mean?
A VUS means the clinical impact of the detected genetic change is not yet established. Follow-up counseling and possible reanalysis are recommended as scientific knowledge evolves.
How are WES results interpreted clinically?
A molecular geneticist and clinical geneticist review identified variants against established databases (ClinVar, OMIM, gnomAD) and classify them per ACMG guidelines before reporting.
Test Description
Test Code
MOG15
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