Chromosomal Microarray 315K Test: Booking, Price, and Results
About Chromosomal Microarray 315K Test
| Field | Value |
|---|---|
| Also Known As | CMA 315K, Chromosomal microarray analysis 315K, Microarray 315K, SNP array, aCGH (array Comparative Genomic Hybridisation) |
| Sample Type | Peripheral blood (EDTA tube), chorionic villi (CVS), amniotic fluid, cord blood, or products of conception (POC) |
| Fasting Required | No fasting required |
| Report Time | 9 days |
| Recommended For | All ages; commonly ordered for children with developmental delay, intellectual disability, autism spectrum disorder, or congenital anomalies; also used in prenatal diagnosis |
| Price | Starting at ₹13,000 |
What is a Chromosomal Microarray 315K Test?
The chromosomal microarray 315K test is a specialised genetic test that scans the entire set of chromosomes to find missing or extra pieces of genetic material. It uses approximately 315,000 probes (reference points) spread across the genome to detect changes that a standard chromosome test may miss. Doctors also refer to it as CMA 315K, aCGH, or SNP Array. A sample of blood, tissue, or fluid is collected depending on the clinical indication.
What Does a Chromosomal Microarray 315K Test Measure?
The chromosomal microarray 315K test procedure looks for several types of chromosomal changes in a single analysis. The table below summarises what the test detects.
| Parameter | What It Means |
|---|---|
| Copy Number Variants (CNVs) | Missing (deletions) or extra (duplications) pieces of chromosomes across the genome |
| Aneuploidy | Abnormal chromosome count, such as trisomy (extra chromosome) or monosomy (missing chromosome) |
| Regions of Homozygosity (ROH) | Chromosome segments where both copies are identical, which may point to related parents or uniparental disomy |
| Uniparental Disomy (UPD) | Inheriting both copies of a chromosome from one parent rather than one from each, relevant in certain imprinting disorders |
| Microdeletion and Microduplication Syndromes | Sub-microscopic gains or losses linked to well-known genetic syndromes |
The minimum size detectable by this array is 1 MB for losses, 2 MB for gains, and 5 MB for regions of homozygosity.
Why is a Chromosomal Microarray 315K Test Done?
The chromosomal microarray 315K test is requested when a doctor needs to identify a possible genetic cause for a child's developmental difficulties or for unexplained findings during pregnancy.
Common Symptoms That May Require This Test
- Unexplained developmental delay or intellectual disability
- Features of autism spectrum disorder
- Multiple congenital anomalies (two or more birth differences present from birth)
- Dysmorphic features (unusual facial or physical features that may suggest a syndrome)
- Seizures without a clear cause
- Recurrent pregnancy loss
Conditions This Test Can Help Detect
This test can help identify a range of genetic conditions, including the following:
- Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13)
- DiGeorge syndrome and velocardiofacial syndrome (22q11.2 deletion), the most common chromosomal microdeletion conditions
- Prader-Willi syndrome and Angelman syndrome (15q11.2-q13 region)
- Williams-Beuren syndrome (7q11.23 deletion) and Smith-Magenis syndrome (17p11.2 deletion)
- 1p36 deletion syndrome and Cri-du-chat syndrome (5p deletion)
- Turner syndrome and Klinefelter syndrome
Chromosomal Microarray 315K Test During Pregnancy
During pregnancy, the chromosomal microarray 315K test is recommended when a fetal structural abnormality is found on an ultrasound scan. The American College of Obstetricians and Gynaecologists recommends CMA as the first-tier diagnostic test when fetal anomalies are detected. It is performed on amniotic fluid or chorionic villus samples and can also be used to investigate stillbirth or recurrent pregnancy loss.
How to Prepare and What to Expect
No special preparation is needed for this test, but there are a few steps that make the process smoother.
Do You Need to Fast?
No fasting is required before the chromosomal microarray 315K test. You may eat and drink normally before your appointment.
Practical Tips Before Your Test
- Bring a detailed clinical history, including your symptoms, previous test results, and family history, as this is required for the test
- Carry a valid doctor's prescription and complete the test request form with your name, age, contact details, and basic health information
- Bring signed informed consent (the mandatory consent G form) as required by the laboratory
- Inform your doctor about all medications you are currently taking
- Genetic counselling is strongly recommended before the test so that you understand what the results may reveal
Step-by-Step Procedure
The collection method depends on the sample type required. Your doctor will advise which applies to you.
Peripheral Blood (EDTA Tube)
- A healthcare professional will clean the skin on your inner arm and draw a small blood sample from a vein using a needle.
- The blood is collected into a special EDTA tube (a lavender-top tube containing a preservative that keeps the sample stable).
- The tube is labelled with your details and stored at 2 to 8 degrees Celsius for transport.
- In the laboratory, DNA is extracted from your blood and applied to the microarray chip.
- The chip is scanned, and the signal patterns are compared against a reference dataset by specialised software and a geneticist.
Chorionic Villus Sampling (CVS)
- A doctor performs the CVS procedure in a clinical setting, usually between 10 and 13 weeks of pregnancy, under ultrasound guidance.
- A small amount of placental tissue (chorionic villi, at least 30 mg) is collected and placed immediately into the media provided by the laboratory or sterile normal saline with two drops of antibiotic solution.
- The sample is transported to the laboratory refrigerated (2 to 8 degrees Celsius) in a sterile container.
- DNA is extracted from the tissue and processed on the microarray platform.
- Results are interpreted by a clinical geneticist in the context of the clinical history provided.
Amniotic Fluid
- A doctor performs amniocentesis in a clinical setting, typically between 15 and 20 weeks of pregnancy, guided by ultrasound.
- A small amount of amniotic fluid is drawn using a fine needle and placed in a sterile container.
- The sample is transported refrigerated and processed in an accredited laboratory for DNA extraction and microarray analysis.
Cord Blood
- Cord blood is collected at the time of delivery or during a clinical procedure, using a sterile collection kit.
- The sample is placed in an EDTA tube or sterile container and transported refrigerated.
- Laboratory analysis follows the same DNA extraction and microarray process as for peripheral blood.
Products of Conception (POC)
- Tissue is collected following pregnancy loss or termination under sterile clinical conditions.
- The sample is placed in the media provided or sterile normal saline with antibiotic drops in a sterile container.
- It is transported refrigerated and processed in the laboratory to identify any chromosomal abnormalities that may explain the pregnancy loss.
Factors That Can Affect Accuracy
The following factors may influence the reliability of your result:
- Poor sample quality or insufficient DNA yield
- Improper storage or transport conditions
- Use of an incorrect collection tube or failure to mix blood with the anticoagulant properly
- Maternal cell contamination in prenatal samples (fetal cells mixed with maternal cells)
- Low-level mosaicism, where only a small proportion of cells carry an abnormality
Understanding Your Chromosomal Microarray 315K Test Results
Results from the chromosomal microarray 315K test are not reported as simple normal or abnormal numbers. Instead, they are classified into the categories below. A clinical geneticist or genetic counsellor will review the findings alongside your clinical history.
| Result Category | What it Means |
|---|---|
| Normal | No missing or extra chromosomal material detected across the genome |
| Pathogenic | A chromosomal change is present that is likely to cause developmental or intellectual difficulties |
| Likely Pathogenic | A chromosomal change that is probably clinically significant, though not yet conclusively confirmed |
| Variant of Unknown Significance (VUS) | A chromosomal change is present, but it is currently unclear whether it causes any clinical problems; this is a common finding |
| Likely Benign / Benign | A chromosomal change is present, but is unlikely to cause any health problems |
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
Copy number variation is present in all individuals, including those without any clinical problems. This makes it challenging to determine the significance of a rare or novel finding. Parental testing is sometimes needed to establish whether a variant is inherited or occurred for the first time (de novo), as this affects how the result is interpreted. Additionally, CMA cannot detect balanced chromosomal rearrangements, where genetic material is rearranged but nothing is gained or lost.
How to Maintain Healthy Levels
Because chromosomal changes detected by this test are present from conception or are inherited, there are no lifestyle changes that can prevent or reverse them. Consider the following instead:
- If a pathogenic variant is found, consult a genetic counsellor to understand what this means for your child and for future pregnancies.
- Early intervention and support programmes for children with genetic conditions can meaningfully improve developmental outcomes.
- For families with a confirmed finding, periodic review with a specialist can help guide appropriate care and support.
Lupin Diagnostics Chromosomal Microarray 315K Test Price and Home Collection
The chromosomal microarray 315K test cost at Lupin Diagnostics starts at ₹13,000. Home collection is available for eligible sample types; a certified professional will visit your home for blood collection, while prenatal and tissue samples must be collected in a clinical setting. The approximate city-wise prices are listed below.
| City | Approximate Price (₹) |
|---|---|
| BHOPAL | 13000 |
| CHENNAI | 13000 |
| HYDERABAD | 13000 |
| KOLKATA | 13000 |
| NAVI MUMBAI | 13000 |
| PUNE | 13000 |
Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
- Select the test on the Lupin Diagnostics website.
- Choose your city and preferred time slot.
- Opt for home sample collection by a certified phlebotomist for blood samples, or visit your nearest Lupin Diagnostics centre for prenatal or tissue samples.
- Receive your report via email or WhatsApp within 9 days.
Home Collection
Lupin Diagnostics offers home collection for peripheral blood samples across multiple cities. All samples are processed in NABL-accredited laboratories by experienced geneticists and technologists. Digital reports are accessible via email or WhatsApp once ready.
Frequently Asked Questions
The numbers refer to how many probes (reference points) are on the array chip. The chromosomal microarray 315K test uses approximately 315,000 probes, which is sufficient to detect most clinically significant chromosomal changes associated with well-known genetic syndromes. The 750K array has a higher resolution and can detect smaller changes, making it suitable for more complex or inconclusive cases.
Results are typically available within 9 days from the date the laboratory receives your sample. Turnaround times may occasionally vary depending on sample quality or the complexity of the findings.
For peripheral blood, the procedure involves a routine blood draw with minimal discomfort. For prenatal samples obtained via CVS or amniocentesis, the procedure is performed by a trained doctor in a clinical setting. Your doctor will explain the associated procedural considerations before you give consent.
A VUS is a chromosomal change where current evidence is insufficient to confidently classify it as either harmful or benign. It is a common finding and does not confirm a diagnosis on its own. Your genetic counsellor will explain what a VUS means in the context of your specific clinical picture and whether any follow-up testing is recommended.
No. The CMA 315K detects chromosomal copy number changes but cannot identify single gene mutations, balanced chromosomal rearrangements, or changes smaller than the detection threshold. If findings remain unexplained, your doctor may recommend additional tests such as whole exome sequencing.
When a copy number variant is found in a child or fetus, testing the parents helps determine whether the change is inherited or occurred spontaneously. This distinction is important because de novo (spontaneous) variants are more often associated with clinical problems, while an inherited variant found in an unaffected parent may be less concerning. Parental testing supports a more accurate interpretation of the result.
Yes, genetic counselling is strongly recommended both before and after the test. The test can reveal unexpected findings or variants whose significance is unclear, and results may have implications for other family members. A genetic counsellor helps you understand what the findings mean, guides decisions about further testing, and supports family planning discussions.
Chromosomal Microarray 315K Test: Booking, Price, and Results
