HLA B 27 Disease Association PCR
- Sample Type
- Whole Blood
- Fasting
- No
- Unit
- N/A
Function
HLA-B27 (Human Leukocyte Antigen B27) is a specific surface antigen found on white blood cells. It is part of the Major Histocompatibility Complex (MHC) and plays a role in how the immune system recognizes foreign substances. The PCR (Polymerase Chain Reaction) test is a highly sensitive molecular method used to detect the presence of the HLA-B27 gene.
Why it is Ordered
This test is ordered when a patient presents with symptoms of inflammatory arthritis, particularly affecting the spine and sacroiliac joints. It is the primary genetic marker for a group of autoimmune diseases known as seronegative spondyloarthropathies. While not a definitive diagnostic test on its own (many healthy people carry the gene), it provides strong supporting evidence when combined with clinical symptoms and imaging (like X-rays or MRI of the pelvis).
Associated Conditions
- Ankylosing Spondylitis (AS): Over 90% of patients with AS are HLA-B27 positive.
- Reactive Arthritis (Reiter’s Syndrome): Often triggered by an infection in another part of the body.
- Psoriatic Arthritis: Inflammation associated with the skin condition psoriasis.
- Acute Anterior Uveitis: Inflammation of the middle layer of the eye.
Check Your Result
Check Your Result
Enter your lab result to see where you stand compared to the standard reference range.
Why Context Matters
Genetic testing via PCR is highly accurate for the presence of the gene, but its clinical interpretation is complex. Up to 8% of the healthy population (depending on ethnicity) carries the HLA-B27 gene but will never develop an autoimmune disease. Therefore, a positive result without symptoms does not mean a patient has a disease. Conversely, a negative result does not 100% rule out these conditions, as a small percentage of patients are HLA-B27 negative.
Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.
Clinical References
Source-of-truth databases and clinical guidelines for HLA B 27 Disease Association PCR:
Official Sources
Research & Guidelines
Related Indicators
Medically Reviewed by Dr. Binoy Babu, MBBS
Board Certified Doctor • 10+ Years Clinical Experience
Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.
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