Achondroplasia Mutation Analysis (FGFR3 Gene G1138A, G1138C) Test
About Achondroplasia Mutation Analysis (FGFR3 Gene G1138A, G1138C) Test
| Field | Value |
|---|---|
| Also Known As | FGFR3 Gene Mutation Analysis, ACH Mutation Test, Achondroplasia Genetic Test, Dwarfism Gene Test |
| Sample Type | Peripheral blood (EDTA tube) |
| Fasting Required | No |
| Report Time | 20 days |
| Recommended For | All ages; newborns, children, or adults with suspected skeletal dysplasia; prenatal testing for at-risk pregnancies |
| Price | Starting at ₹9,000 |
What is an Achondroplasia Mutation Analysis (FGFR3 Gene G1138A, G1138C) Test?
The Achondroplasia Mutation Analysis (FGFR3 Gene G1138A, G1138C) test is a molecular genetic test that checks for specific mutations in the FGFR3 gene. These two mutations, G1138A and G1138C, are responsible for the vast majority of achondroplasia cases. Achondroplasia is the most common form of short-limb dwarfism in humans.
A doctor may prescribe this achondroplasia genetic test when physical features suggest a skeletal growth disorder, or when a family history of the condition exists. A small blood sample collected into an EDTA tube is used for the analysis.
What Does an Achondroplasia Mutation Analysis (FGFR3 Gene G1138A, G1138C) Test Measure?
This test analyses two specific mutations at position 1138 of the FGFR3 gene. The FGFR3 gene carries instructions for a protein that helps regulate bone and brain tissue development. When either mutation is present, the protein becomes overactive and interferes with the normal growth of long bones.
The two mutations examined are described below.
| Mutation | What it Involves |
|---|---|
| FGFR3 c.1138G>A (G1138A) | A change from G to A at nucleotide position 1138; found in approximately 98% of achondroplasia cases |
| FGFR3 c.1138G>C (G1138C) | A change from G to C at the same position; found in approximately 1% of achondroplasia cases |
Both mutations lead to a change at codon 380 of the FGFR3 protein, causing the receptor to remain constantly active. This constant activation excessively inhibits the growth of cartilage cells in the long bones.
Why is an Achondroplasia Mutation Analysis (FGFR3 Gene G1138A, G1138C) Test Done?
A doctor may request this test when clinical or family history details point towards achondroplasia or a related skeletal condition. The sections below outline common reasons for testing.
Common Symptoms That May Require This Test
The following physical features often prompt a doctor to recommend this test.
- Noticeably short limbs, particularly in the upper arms and thighs
- A larger-than-usual head size (macrocephaly)
- A prominent forehead with a flattened mid-face
- An exaggerated inward curve of the lower spine (lumbar lordosis)
- Short, broad fingers with a trident hand appearance
- Bowing of the legs (genu varum)
- Limited straightening of the elbows
Conditions This Test Can Help Detect
This FGFR3 gene mutation analysis can help identify the following conditions.
- Achondroplasia, an autosomal dominant genetic disorder causing disproportionate short stature
- Health complications associated with achondroplasia include spinal canal narrowing (spinal stenosis), interrupted breathing during sleep (apnoea), fluid build-up in the brain (hydrocephalus), and recurrent ear infections
Achondroplasia Mutation Analysis (FGFR3 Gene G1138A, G1138C) Test During Pregnancy
Prenatal testing for achondroplasia is possible and is recommended when one or both parents carry the condition. Testing can be carried out using chorionic villus sampling (CVS) at around 11 to 13 weeks of pregnancy, or via amniocentesis from 15 weeks onwards.
Non-invasive prenatal testing panels now include these specific FGFR3 variants, enabling detection as early as 9 to 10 weeks. Achondroplasia may also be picked up incidentally during routine ultrasound scans in the second or third trimester if foetal long bone shortening is observed.
How to Prepare and What to Expect
No special preparation is needed for this test. The steps below explain what the experience typically involves.
Do You Need to Fast?
No, fasting is not required before the achondroplasia mutation analysis test. You may eat and drink normally on the day of sample collection.
Practical Tips Before Your Test
A few simple steps will help the process go smoothly.
- Bring a detailed clinical history, including your symptoms, previous test results, and family history, as this is required for the test
- Inform your doctor of any medications you are currently taking or any underlying health conditions
- Bring relevant imaging reports (such as X-rays) and previous genetic test results if available
- Genetic counselling is recommended both before and after the test to help understand the implications of the results
- For prenatal testing, confirm the timing and method with your doctor well in advance
Step-by-Step Procedure
The following steps describe what happens during sample collection.
- A trained phlebotomist will clean the area inside your elbow with an antiseptic wipe.
- A small blood sample of 2 ml is drawn from a vein in your arm using a fine needle.
- The blood is collected into a lavender-capped EDTA tube to preserve the DNA.
- The tube is labelled with your name, registration number, and the date of collection.
- The sample is stored under refrigeration (2 to 8°C) and transported to a specialised molecular genetics laboratory.
- The laboratory analyses the sample using Sanger sequencing to identify the presence or absence of the G1138A or G1138C mutations.
Factors That Can Affect Accuracy
The following factors may influence the reliability of your result.
- Poor sample quality or incorrect labelling of the collection tube
- Delay in transporting the sample to the laboratory
- The test targets the two most common FGFR3 mutations; rare or unusual variants may not be detected
- Contaminated samples
Understanding Your Achondroplasia Mutation Analysis (FGFR3 Gene G1138A, G1138C) Test Results
Your results will indicate whether either of the two targeted FGFR3 mutations was detected. A doctor or genetic counsellor should always review the findings alongside your clinical features and family history.
| Parameter | Normal Result | Interpretation of Detected Mutation |
|---|---|---|
| FGFR3 c.1138G>A (G1138A) | Not detected | Pathogenic variant associated with achondroplasia |
| FGFR3 c.1138G>C (G1138C) | Not detected | Pathogenic variant associated with achondroplasia |
A result showing no mutation detected makes achondroplasia unlikely. However, a small number of rare variants may not be identified by this targeted analysis. If clinical suspicion remains, your doctor may suggest further genetic investigation.
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.
How to Maintain Healthy Levels
This is a genetic test, and its result reflects your inherited DNA, which does not change over time. The following points may help after receiving your result.
- Discuss your results with a geneticist or genetic counsellor who can explain the findings in full context.
- If the mutation is confirmed, regular follow-up with a specialist can help monitor and manage associated health concerns such as spinal stenosis and sleep apnoea.
- Early awareness of the diagnosis allows families to plan appropriate medical support and monitoring from an early stage.
Lupin Diagnostics Achondroplasia Mutation Analysis (FGFR3 Gene G1138A, G1138C) Test Price and Home Collection
The Achondroplasia Mutation Analysis test cost at Lupin Diagnostics starts at ₹9,000, and home sample collection is available. The table below shows indicative pricing across cities.
| City | Approximate Price (₹) |
|---|---|
| BHOPAL | 9000 |
| CHENNAI | 9000 |
| HYDERABAD | 9000 |
| KOLKATA | 9000 |
| NAVI MUMBAI | 9000 |
| PUNE | 9000 |
Disclaimer: Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
Booking your achondroplasia mutation analysis test online is straightforward.
- 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
Lupin Diagnostics offers home sample collection for this test across multiple cities. All samples are processed in NABL-accredited laboratories by experienced molecular genetics teams. Once ready, reports are shared digitally via email or WhatsApp for convenient access.
Frequently Asked Questions
This is a genetic test that checks for two specific mutations in the FGFR3 gene. These mutations, known as G1138A and G1138C, together account for nearly all confirmed cases of achondroplasia. The test is performed using a blood sample analysed by Sanger sequencing.
This test is suitable for individuals who show physical signs suggesting a skeletal growth disorder, or where a family history of achondroplasia exists. It is also relevant for expectant parents who carry or are suspected of carrying the condition, as prenatal testing options are available.
Yes. Prenatal testing is possible through chorionic villus sampling at 11 to 13 weeks or amniocentesis from 15 weeks onwards. Non-invasive prenatal testing may detect the mutation as early as 9 to 10 weeks. Speak to your doctor about which option is most appropriate for your situation.
For adults and children, the test requires a standard blood draw, which involves brief discomfort at the needle site and occasionally minor bruising. Prenatal sampling methods carry their own considerations, which your doctor will explain in detail before the procedure.
The report is typically available within 20 days from the date of sample collection. This reflects the time required for Sanger sequencing analysis in a specialised molecular genetics laboratory.
A positive result means one of the two targeted FGFR3 mutations was detected. This confirms a genetic basis for achondroplasia when the clinical picture is consistent. Your doctor or genetic counsellor will discuss what the finding means for you or your child and what steps to consider next.
Not entirely. A negative result means the two most common mutations were not found, making achondroplasia unlikely. However, a very small number of rare FGFR3 variants fall outside the scope of this targeted analysis. If symptoms remain unexplained, your doctor may recommend broader genetic testing.
Achondroplasia Mutation Analysis (FGFR3 Gene G1138A, G1138C) Test
