The test uses capillary sequencing (Sanger), a well-established method for analysing DNA, to examine targeted regions of the baby’s genome. It specifically looks for known mutations that may cause genetic disorders. Because it focuses on precise areas of concern rather than scanning the entire genome, it delivers clear and reliable confirmation, which is particularly useful when verifying findings from broader genetic tests like next generation sequencing (NGS).
Targeted Variant Testing
What is a Targeted Variant Testing?
Targeted variant testing is a targeted genetic test used during pregnancy to confirm the presence of specific, known mutations in the fetus. It is most commonly recommended when one or both parents are carriers of a known genetic condition or when a variant of concern has been identified through broader screening, such as next-generation sequencing (NGS). Unlike general screening tests, targeted variant testing focuses on a precise region of the DNA, delivering highly accurate, confirmatory results.
How Does the Targeted Variant Testing Work?
| Step | Description | |
|---|---|---|
| 1. Sample Collection | A sample is collected through amniocentesis or chorionic villus sampling (CVS). | |
| 2. Order & Primer Design | The test is booked, and two sets of custom primers are designed for each case to ensure specificity and accuracy. | |
| 3. DNA Extraction & QC | DNA is extracted from the sample and undergoes quality control checks before testing. | |
| 4. PCR Amplification | The target DNA region is amplified using validated in-house primers and internal controls to confirm accuracy. | |
| 5. Targeted Sequencing | The amplified DNA is subjected to capillary sequencing (Sanger) to detect the specific gene mutation. | |
| 6. Result Interpretation | Sequencing data is analysed, and a clinician-friendly report is generated. | |
| 7. Genetic Counseling Support | Patients and providers receive expert genetic counseling to interpret results and plan next steps. |
Why Choose Targeted Variant Testing?
- Gold Standard for Single-Gene Disorders:
Capillary sequencing (Sanger) is widely recognised as the most reliable method for detecting known, inherited mutations, offering exceptional accuracy for single-gene analysis. - Precise and Confirmatory:
Ideal for validating specific variants identified through broader methods like Next-Generation Sequencing (NGS), ensuring clarity and confidence in clinical decision-making.
Specifications
- Test Method: Targeted capillary sequencing (Sanger) (bi-directional).
- Sample Type: Amniotic fluid or chorionic villus sampling (CVS).
- Turnaround Time: Typically 21 working days.
- Validation: Internal controls (proband/index DNA).
When to Use Targeted Variant Testing?
Carrier Mutation Confirmation
Recommended when one or both parents are carriers of a known genetic disorder (e.g., Thalassemia, cystic fibrosis, sickle cell anemia).
NGS Variant Validation
Ideal for confirming uncertain or low-confidence results from next-generation sequencing (NGS).
Key Highlights of MedGenome's Targeted Variant Testing
High Precision & Reliability
Each case is processed using two distinct primer sets and internal controls (index/proband) to ensure accurate detection and quality validation.
Cost-Effective for Single-Gene Analysis
Ideal for targeted testing when a specific genetic mutation is already known in the family.
Clarity for Known Variants
Helps reduce diagnostic uncertainty by precisely confirming inherited mutations.
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