RB1 Gene Deletion & Duplication Detection (Retinoblastoma) Test
About RB1 Gene Deletion & Duplication Detection (Retinoblastoma) Test
| Field | Value |
|---|---|
| Also Known As | RB1 Deletion/Duplication Analysis Test, Retinoblastoma Gene Testing, RB1 Copy Number Variation (CNV) Test, RB1 MLPA Test |
| Sample Type | Peripheral blood (EDTA tube) |
| Fasting Required | No fasting required |
| Report Time | 15 days |
| Recommended For | Children with suspected or confirmed retinoblastoma; at-risk family members of affected individuals |
| Price | Starting at ₹10,200 |
What is an RB1 Gene Deletion & Duplication Detection (Retinoblastoma) Test?
The RB1 Gene Deletion & Duplication Detection test analyses a blood sample to identify missing or extra segments in the RB1 gene, which is responsible for suppressing abnormal cell growth in the retina (the light-sensitive layer at the back of the eye).
It is most commonly ordered for children diagnosed with retinoblastoma, a rare eye tumour, and for family members who may carry the same inherited change. The test is also known as the RB1 Deletion/Duplication Analysis test or the RB1 MLPA test, after the laboratory method used.
What Does an RB1 Gene Deletion & Duplication Detection (Retinoblastoma) Test Measure?
This test examines the RB1 gene on chromosome 13 for two specific types of changes. The table below explains each component.
| Component | What It Looks For |
|---|---|
| RB1 gene deletions | Missing segments of the gene, ranging from a single exon (a coding unit) to the entire gene |
| RB1 gene duplications | Extra copies of genetic segments within the RB1 gene |
| RB1 gene copy number | Whether the expected two copies of the gene are present in every cell |
| Exon-level analysis | Whether all individual coding sections of the gene are intact and present |
Results are reported as negative (no change found), positive (a deletion or duplication identified), or a variant of uncertain significance (a change detected whose clinical meaning is not yet clear).
Why is an RB1 Gene Deletion & Duplication Detection (Retinoblastoma) Test Done?
This test is ordered when a doctor suspects retinoblastoma or when a family history of the condition has been confirmed. It helps classify risk, guide follow-up care, and inform decisions about screening for other family members.
Common Symptoms That May Require This Test
The following symptoms in a child may prompt a doctor to recommend genetic testing:
- Leukocoria (a white glow or white colour visible in the pupil), the most common early sign
- White pupil appearing in photographs when a flash is used
- Strabismus (a squint or cross-eyed appearance)
- Eye redness or inflammation without an obvious cause
- Reduced or impaired vision in one or both eyes
Conditions This Test Can Help Detect
A doctor may order the RB1 gene deletion & duplication detection test to help identify the following:
- Retinoblastoma, a malignant tumour of the retina in young children
- Heritable retinoblastoma, which accounts for 30 to 40% of all cases and involves a germline (inherited) RB1 mutation
- Chromosome 13q14 deletion syndrome, seen in approximately 6 to 8% of cases and sometimes associated with developmental delay
- Increased lifetime risk of secondary tumours, including osteosarcoma (bone cancer), soft tissue sarcoma, and melanoma
How to Prepare and What to Expect
No special preparation is needed for this test. The steps involved are straightforward and the blood draw is brief.
Do You Need to Fast?
No fasting is required before this test. You may eat and drink normally before your appointment.
Practical Tips Before Your Test
Keep the following points in mind before attending your sample collection:
- Bring a detailed clinical history, including symptoms, previous test results, and family history, as this is required for the test
- Inform the laboratory if the patient has recently received a blood transfusion or bone marrow transplant, as this can affect results
- If the patient has a history of hematologic (blood-related) malignancy or a bone marrow transplant, let the doctor know, as an alternative sample type may be needed
- Genetic counselling before testing is recommended to help the family understand the purpose and implications of the test
- Wear loose, comfortable clothing with easy access to the arm for the blood draw
Step-by-Step Procedure
The RB1 gene deletion & duplication detection test procedure involves a simple blood collection. Here is what to expect:
- A trained phlebotomist (a specialist who collects blood samples) identifies a suitable vein, usually in the arm
- The area is cleaned with an antiseptic solution
- A small peripheral blood sample of 2 ml is collected into an EDTA (lavender-top) tube via venepuncture (drawing blood from a vein)
- The tube is labelled with the patient's details and the date of collection
- The sample is stored under refrigeration at 2 to 8 degrees Celsius and dispatched to the laboratory
- In the laboratory, DNA is extracted from the blood and analysed using the MLPA (Multiplex Ligation-dependent Probe Amplification) method
Factors That Can Affect Accuracy
Several factors may influence the reliability of your result:
- Recent blood transfusion or bone marrow transplant in the patient
- Mosaicism, where only a fraction of cells carry the mutation, which may reduce detection sensitivity
- Sample quality and storage conditions
- Promoter hypermethylation, a separate type of RB1 change not detectable by this test
- The specific laboratory method used
Understanding Your RB1 Gene Deletion & Duplication Detection (Retinoblastoma) Test Results
Results should always be reviewed with a qualified doctor or genetic counsellor. The table below shows how findings are generally interpreted.
| Result | Meaning |
|---|---|
| No deletion or duplication detected | Normal — two copies of the RB1 gene are present with no identified change |
| Deletion or duplication detected | A pathogenic (disease-causing) change has been found in the RB1 gene |
| Variant of uncertain significance | A genetic change was found, but its clinical significance is currently unclear |
Disclaimer: These ranges are general guidelines. Your doctor will interpret your results based on your age, health history, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
Results During Special Conditions
Certain situations can affect how results are interpreted:
Mosaicism: When only a portion of cells carry the RB1 mutation, very sensitive methods such as NGS (next-generation sequencing) may be needed to detect it. Standard MLPA may not identify mosaic variants at low levels.
Prior bone marrow transplant: Peripheral blood results may reflect the donor's DNA rather than the patient's. In such cases, testing on skin cells (cultured fibroblasts) may be more appropriate.
Promoter hypermethylation: Approximately 10 to 12% of RB1 changes are caused by this mechanism and will not show up on a deletion and duplication test alone. Additional testing may be required.
Follow-Up Care and Risk Management
This is a genetic test, so lifestyle changes do not alter results. The following general steps can help manage risk in confirmed carriers:
- Ensure at-risk family members are screened early, as prompt detection helps preserve vision and prevent disease progression
- Minimise unnecessary radiation exposure, such as X-rays and CT scans, in individuals confirmed to carry an RB1 mutation, to reduce the lifetime risk of secondary cancers
- Attend all follow-up appointments recommended by the treating specialist
Lupin Diagnostics RB1 Gene Deletion & Duplication Detection (Retinoblastoma) Test Price
The RB1 Gene Deletion & Duplication Detection test cost at Lupin Diagnostics starts at ₹10,200. This test requires a visit to a centre.
| City | Approximate Price (₹) |
|---|---|
| BHOPAL | 10200 |
| CHENNAI | 10200 |
| HYDERABAD | 10200 |
| KOLKATA | 10200 |
| NAVI MUMBAI | 10200 |
| PUNE | 10200 |
Disclaimer: Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
Follow these steps to book your RB1 Gene Deletion & Duplication Detection test online:
- Select the test on the Lupin Diagnostics website
- Choose your city and preferred centre location
- Visit the centre at your scheduled time for sample collection
- Receive your report via email or WhatsApp within the stipulated turnaround time
Frequently Asked Questions
The RB1 Gene Deletion & Duplication Detection test is a genetic test that examines a blood sample for missing or extra segments in the RB1 gene. These changes can cause retinoblastoma, a rare eye tumour in young children. The test uses a laboratory method called MLPA to detect copy number changes at the level of individual gene segments.
This test is primarily recommended for children diagnosed with retinoblastoma and for their close relatives, including siblings and parents. It helps determine whether the condition is inherited and guides surveillance for other family members who may be at risk.
No fasting is required. You may eat and drink as normal before your appointment. The only preparation needed is to bring a detailed clinical history, as this is required for the test.
The report is available within 15 days of sample collection. This turnaround time accounts for the detailed genetic analysis involved in the RB1 Gene Deletion & Duplication Detection test procedure.
A positive result means a deletion or duplication was identified in the RB1 gene. This finding is associated with a high likelihood of retinoblastoma and an increased lifetime risk of certain secondary cancers. Your doctor or genetic counsellor will explain the next steps in detail.
No. A negative result means no deletion or duplication was found, but it does not exclude all forms of heritable retinoblastoma. Other types of RB1 changes, such as point mutations or promoter methylation, are not detected by this test and may require separate analysis.
Genetic counselling is strongly recommended both before and after testing. It helps families understand what the RB1 Gene Deletion & Duplication Detection test can and cannot confirm, and what a result means for other family members, particularly when retinoblastoma has affected more than one person in the family or both eyes of the same individual.
RB1 Gene Deletion & Duplication Detection (Retinoblastoma) Test
