GCH1 Gene Hyperphenylalaninemia, BH4-deficient, B NGS Genetic Test
Short Name: GCH1 BH4 Deficiency NGS
Also known as: GCH1 Gene Mutation Analysis, BH4-Deficient Hyperphenylalaninemia Type B Test, GCH1-Related Hyperphenylalaninemia NGS Panel
GCH1 Gene Hyperphenylalaninemia, BH4-deficient, B NGS Genetic Test test available at DNA Labs India for ₹20,000. Uses Next Generation Sequencing (NGS) on Blood or Extracted DNA or One Drop Blood on FTA Card samples. Results in Reports are usually issued 3 to 4 weeks after the sample reaches the laboratory. Raw data files (FASTQ and VCF) are shared along with the clinical report.. Free home collection in 300+ cities across India.
🩺 Medically Reviewed By
Dr SULOCHANA HEMCHANDRA HOLLA
Consultant Medical Geneticist · Reg: 8532
Last reviewed: September 7, 2026
Overview
The purpose of this NGS-based genetic test is to detect pathogenic or likely pathogenic variants in the GCH1 gene that cause hyperphenylalaninemia and BH4-deficient type B disease. The result helps confirm the clinical diagnosis, distinguish it from other forms of hyperphenylalaninemia, guide treatment, and support genetic counseling.
- Test Code
- 4147
- Price
- ₹20,000
- Sample Type
- Blood or Extracted DNA or One Drop Blood on FTA Card
- Result Time
- Reports are usually issued 3 to 4 weeks after the sample reaches the laboratory. Raw data files (FASTQ and VCF) are shared along with the clinical report.
- Fasting Required
- No
- Method
- Next Generation Sequencing (NGS)
Sample Collection
No fasting is required. Please complete the genetic counseling session and informed consent before sample collection. Bring any previous metabolic or genetic test reports if available.
Method: Venipuncture or dried blood spot collection
Laboratory Analysis
A small volume of blood will be collected by a trained technician. For FTA card collection, a few drops of blood will be placed on the provided card.
Report Delivery
No special precautions are needed. You may resume normal diet and activities immediately after sample collection.
Timeline: Reports are usually issued 3 to 4 weeks after the sample reaches the laboratory. Raw data files (FASTQ and VCF) are shared along with the clinical report.
Patient Instructions
About This Test
Who Should Get This Test
The purpose of this NGS-based genetic test is to detect pathogenic or likely pathogenic variants in the GCH1 gene that cause hyperphenylalaninemia and BH4-deficient type B disease. The result helps confirm the clinical diagnosis, distinguish it from other forms of hyperphenylalaninemia, guide treatment, and support genetic counseling.
How to Prepare
- Confirm patient identity before sample collection.
- Use an EDTA vacutainer for whole blood collection.
- For FTA card, apply one drop of blood onto each marked circle.
- Label the sample with patient name, unique ID, and date of collection.
- Transport the sample to the laboratory at ambient temperature, avoiding extreme heat or freezing.
Doctor's Notes
Reviewed by Dr SULOCHANA HEMCHANDRA HOLLA — MBBS, MD (Medical Genetics) · Reg. No. 8532
"A confirmed genetic diagnosis of hyperphenylalaninemia allows targeted treatment, cofactor supplementation, and informed reproductive counseling. Couples with a family history should seek preconception genetic advice before planning a pregnancy."
Last medically reviewed: September 7, 2026
Test Parameters & Specifications
Sample Stability
- Clotted or visibly hemolyzed blood sample.
- Insufficient sample quantity for DNA extraction.
- Missing or incorrect patient identification on sample tube.
- Leaking sample container.
- Improper sample storage or transport conditions.
Understanding Your Results
Pathogenic variant identified
Confirms GCH1-related hyperphenylalaninemia and supports targeted management and family counseling.
Likely pathogenic variant identified
Very likely disease-causing; additional evidence from family segregation or clinical findings may be needed.
Variant of uncertain significance (VUS)
Cannot confirm or exclude disease at this time. Further family testing and genetic evaluation are recommended.
No pathogenic variant identified
Does not rule out hyperphenylalaninemia caused by variants in genes not covered or variants not detectable by this method.
If phenylalanine levels are elevated, if neurological symptoms are present, or if the genetic report is positive or shows a variant of uncertain significance, consult a clinical geneticist or metabolic specialist promptly.
Limitations
- ⚠NGS may not detect large gene rearrangements, deep intronic variants, or certain regulatory mutations in GCH1.
- ⚠A variant of uncertain significance may require additional family segregation studies.
- ⚠This test does not measure blood phenylalanine, enzyme activity, or BH4 cofactor levels.
- ⚠A negative result does not exclude all genetic causes of hyperphenylalaninemia.
Risks & Considerations
- ●Minor pain or bruising at the blood collection site.
- ●Rare risk of infection at the venepuncture site.
- ●Emotional or psychological anxiety related to genetic testing results.
Interfering Factors
- ●Incomplete clinical information may affect variant interpretation.
- ●DNA contamination or degradation during sample transport.
- ●Recent blood transfusion or bone marrow transplant may alter blood DNA results.
- ●Targeted GCH1 analysis does not detect variants in other hyperphenylalaninemia genes.
Compare With Similar Tests
| Test | GCH1 Gene Hyperphenylalaninemia, BH4-deficient, B NGS Genetic Test | |||
|---|---|---|---|---|
| Comparison | GCH1 Gene Hyperphenylalaninemia, BH4-deficient, B NGS Genetic Test | Sequences only the GCH1 gene. Best to confirm GCH1-related hyperphenylalaninemia and BH4-deficient type B. | Sequences multiple genes including PAH, PTS, QDPR, and GCH1 for a broader differential diagnosis. | Biochemical screening test that measures phenylalanine concentration. It is not a genetic test and does not identify the underlying gene mutation. |
Frequently Asked Questions
What is GCH1 gene hyperphenylalaninemia?
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