Williams Syndrome (Karyotyping+FISH) Test
About Williams Syndrome (Karyotyping+FISH) Test
| Field | Value |
|---|---|
| Also Known As | Williams-Beuren Syndrome Test, WBS FISH Test, 7q11.23 Deletion Test, Williams Syndrome Chromosome Analysis Test |
| Sample Type | Peripheral blood |
| Fasting Required | No fasting required |
| Report Time | 12 days |
| Recommended For | All ages; typically ordered for infants and children with characteristic features |
| Price | Starting at ₹7,800 |
What is a Williams Syndrome (Karyotyping+FISH) Test?
The Williams Syndrome (Karyotyping+FISH) test is a specialised genetic test that checks for a small deletion on chromosome 7. This deletion causes Williams syndrome, a rare condition affecting physical development, the heart, and learning.
The test uses peripheral blood and combines two laboratory methods — karyotyping and FISH — to detect chromosomal changes that cannot be seen through a standard blood count. It is also referred to as the Williams-Beuren Syndrome test and the 7q11.23 Deletion test.
What Does a Williams Syndrome (Karyotyping+FISH) Test Measure?
This test analyses chromosomes in two ways. Together, the two methods give a clear picture of whether the chromosome 7 deletion linked to Williams syndrome is present.
| Component | What It Does |
|---|---|
| Karyotyping | Photographs and arranges all 46 chromosomes to detect major structural or numerical changes |
| FISH (Fluorescence In Situ Hybridisation) | Uses fluorescent probes targeting the elastin gene on chromosome 7q11.23 to detect the specific deletion that causes Williams syndrome |
A normal result shows two fluorescent signals (one on each copy of chromosome 7). A single signal indicates the deletion is present.
Why is a Williams Syndrome (Karyotyping+FISH) Test Done?
This test is ordered when a doctor suspects Williams syndrome based on a patient's physical features, heart condition, or developmental history. Below are the main reasons a doctor may request it.
Common Symptoms That May Require This Test
The following symptoms are among the most common reasons this test is requested:
- Developmental delay or delayed speech milestones
- Distinctive facial features, sometimes described as elfin-like
- Heart or blood vessel problems, particularly supravalvular aortic stenosis (a narrowing of the main artery from the heart)
- Mild to moderate intellectual disability or learning difficulties
- Unusually sociable or outgoing personality
- Poor growth or short stature
- Connective tissue problems or joint abnormalities
Conditions This Test Can Help Detect
This test can help identify the following conditions:
- Williams syndrome (Williams-Beuren Syndrome), caused by a deletion of genetic material at chromosome 7q11.23
- Other chromosomal abnormalities, including translocations in the chromosome 7 region, which may be identified through the karyotyping component if the FISH result is negative
How to Prepare and What to Expect
No complex preparation is needed for this test. A few simple steps will help ensure the sample is collected and transported correctly.
Do You Need to Fast?
No fasting is required before this test. You may eat and drink as normal before your appointment.
Practical Tips Before Your Test
Keep the following points in mind before you come in for collection:
- Bring a detailed clinical history, including your child's symptoms, previous test results, and family history
- Inform the collection staff of any relevant medical background or suspected diagnosis
- Wear clothing with easy access to the inner arm for a smooth blood draw
- Stay well hydrated, as this makes vein access easier
- No dietary restrictions or medication changes are required
Step-by-Step Procedure
Here is what to expect during the Williams Syndrome (Karyotyping+FISH) test procedure:
- A trained phlebotomist (blood collection professional) cleans the inner arm with an antiseptic solution.
- A small amount of peripheral blood (approximately 3 ml) is drawn from a vein using a sterile needle and collected into a sodium heparin (green-top) tube.
- The sample is labelled carefully and stored at 2 to 8 degrees Celsius for transport to the laboratory.
- In the laboratory, white blood cells from the sample are cultured and stimulated to divide. Cell division is then paused at the stage where chromosomes are most visible.
- For karyotyping, the chromosomes are fixed on a slide, stained, and photographed so specialists can examine them for structural or numerical changes.
- For FISH, fluorescently labelled probes targeting the elastin gene region on chromosome 7 are applied to the chromosomes. The results are visualised under a fluorescence microscope to check whether one or both copies of the gene are present.
Factors That Can Affect Accuracy
The following factors can influence the reliability of this test:
- A clotted or hemolysed (broken-down) blood sample
- Use of an incorrect collection tube (sodium heparin is required)
- Delays in transporting the sample to the laboratory
- In rare cases, Williams syndrome may be caused by a very small mutation rather than a large deletion; FISH may not detect such small changes
- Prior chemotherapy, which can cause chromosome breaks that affect karyotyping results
Understanding Your Williams Syndrome (Karyotyping+FISH) Test Results
Results from this test require careful interpretation by a qualified doctor or clinical geneticist. The table below explains what normal and abnormal findings typically indicate.
| Parameter | Normal Finding | Abnormal Finding |
|---|---|---|
| Karyotype | 46,XX (female) or 46,XY (male), normal chromosome number and structure | Any numerical or structural chromosomal abnormality |
| FISH for 7q11.23 (ELN gene) | Two fluorescent signals, indicating both copies of the elastin gene are present | One fluorescent signal, indicating the 7q11.23 deletion associated with Williams syndrome |
A deletion at 7q11.23 is identified by FISH in approximately 99% of confirmed Williams syndrome cases.
Disclaimer: This information serves as a general guide. Your doctor will evaluate your cytogenetic results alongside your clinical background, symptoms, and other diagnostic findings. Always consult a qualified healthcare professional for personalised medical advice.
Clinical Management & Next Steps
This is a genetic test, so the result itself does not change with lifestyle. However, early action after a positive diagnosis makes a meaningful difference:
- Early diagnosis allows doctors to monitor and manage cardiovascular and developmental concerns promptly.
- Regular follow-up with specialists, including cardiologists, endocrinologists, and developmental pediatricians supports ongoing health management.
- Conditions such as high blood calcium (hypercalcemia) and thyroid issues, which are associated with Williams syndrome, can be monitored and managed with appropriate specialist care.
Lupin Diagnostics Williams Syndrome (Karyotyping+FISH) Test Price and Home Collection
The Williams Syndrome (Karyotyping+FISH) test cost at Lupin Diagnostics starts at ₹7,800, and home collection is available across cities.
| City | Approximate Price (₹) |
|---|---|
| BHOPAL | 7800 |
| CHENNAI | 7800 |
| HYDERABAD | 7800 |
| KOLKATA | 7800 |
| NAVI MUMBAI | 7800 |
| PUNE | 7800 |
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 Williams Syndrome (Karyotyping+FISH) test online:
- Select the test on the Lupin Diagnostics website
- Choose your city and preferred time slot
- Opt for home sample collection by a certified phlebotomist, or visit your nearest Lupin Diagnostics centre
- Receive your report via email or WhatsApp within the stipulated turnaround time
Home Collection
Williams Syndrome (Karyotyping+FISH) test home collection is available across major cities through Lupin Diagnostics. A certified phlebotomist visits your home at a convenient time to collect the blood sample. All samples are processed in NABL-accredited laboratories, and digital reports are shared via email or WhatsApp once ready.
Frequently Asked Questions
Williams syndrome is a rare genetic condition caused by a small deletion on chromosome 7. It affects the heart, development, learning, and physical features. The Williams Syndrome (Karyotyping+FISH) test is ordered when a doctor notices signs such as a specific facial appearance, heart defects, or developmental delays, and wants to confirm or rule out the diagnosis.
The deletion responsible for Williams syndrome is too small to be seen through standard chromosome analysis alone. FISH uses targeted fluorescent probes to detect this specific deletion at chromosome 7q11.23, while karyotyping checks the full set of chromosomes for any other structural changes that may be present alongside or instead of the expected deletion.
The FISH component detects the 7q11.23 deletion in approximately 99% of confirmed Williams syndrome cases, making it a highly reliable diagnostic tool. In a very small number of cases, the syndrome may be caused by a tiny mutation that FISH cannot detect, and additional testing may be recommended.
This specific test uses peripheral blood and is designed for postnatal diagnosis. However, if a parent has Williams syndrome, prenatal testing using amniotic fluid or chorionic villus sampling (a sample from the placenta) is available for high-risk pregnancies. A clinical geneticist can advise on suitable options.
Reports are typically available within 12 days of sample collection. This is because chromosomes must be cultured and grown in a laboratory before analysis can begin, which takes considerably longer than a routine blood test.
No fasting or dietary changes are required. You simply need to bring a detailed clinical history to your appointment, as this is required for the test. The blood sample is collected using a standard venepuncture procedure, and no other preparation is necessary.
A positive result confirms the presence of the 7q11.23 deletion and supports a diagnosis of Williams syndrome. The next step is a referral to a multidisciplinary team, which may include a cardiologist, endocrinologist, geneticist, and developmental pediatrician, for ongoing monitoring and support. A positive result does not mean treatment begins immediately; it guides the medical team in planning appropriate care.
Williams Syndrome (Karyotyping+FISH) Test
