What is HLA B27 Allele by PCR Lab Test?
HLA-B27 (Human leukocyte antigen B27) is specific protein found on the cell surface. This term is also referred to the gene which codes HLA-B27 protein. Hence, this test is said to determine the absence or presence of HLA-B27 protein on white blood cell surface. The HLA are proteins which help body’s immune system in identifying its own cells & differentiate among “self” and “nonself”. However, HLA B27 class 1 allele has been linked to causing autoimmune diseases like ankylosing spondylitis (rare type of arthritis), juvenile rheumatoid arthritis (arthritis in children ages 16 or younger) etc.
More than 90% cases with ankylosing spondylitis have been known to possess HLA-B27 allele (allele = one of two, or more forms of a given gene variant), while only 1% develop into a disease. Therefore, it is known to be of great diagnostic value. For HLA-B27 allele detection, an allele-specific PCR (polymerase chain reaction; method which rapidly makes millions to billions copies of specific DNA sample & amplify it to make it easier for study by the scientist) method is used.
Why is HLA B27 Allele by PCR lab test done?
This test is ordered or used:
- To help strengthen/confirm the suspected diagnosis of autoimmune disorders like ankylosing spondylitis, reactive arthritis, or juvenile rheumatoid arthritis (JRA).
- It is not a definitive test which will diagnose or rule out a disorder. Rather the results add information & act as a piece of evidence along with other evaluation of signs, symptoms & laboratory tests which together support the diagnosis of autoimmune disorders
- As a part of group tests diagnosing & evaluating conditions producing arthritis-like chronic joint pain, inflammation & stiffness
- To help evaluate recurrent uveitis (eye inflammation)
- What do you mean by HLA B27 test by PCR?
It is a blood test done to identify HLA-B27 proteins. These HLA proteins are found on WBC’s.
- What is meant by HLA B27 positive?
It means you contain HLA-B27 in your blood & have higher to average risks of autoimmune diseases like ankylosing spondylitis.
- What therapy can be given to HLA B27 positive patients?
The main step would be to impart patient education with physical & occupational therapy. NSAIDs (Nonsteroidal anti-inflammatory drugs) may also help in reducing joint pain & inflammation.
- Which diseases are associated with HLA B27?
Diseases associated can be memorized with mnemonic PAIR which means Psoriasis, Ankylosing spondylitis (AS), Inflammatory bowel disease, Reactive arthritis.
- Is there any cure present for HLA B27?
No such cure for AS has been found, rather symptomatic treatment is given. Treatment can help prevent or delay process of flushing (spine joining up) & stiffening.
INTERPRETATION OF THE RESULTS:
- “Positive”: means person tested is at increased risk of developing certain autoimmune disorders. This is supported when the person is also suffering from symptoms like chronic pain/inflammation/or degenerative bones, young, male & experiencing before 40.
- “Negative”: means marker (HLA-B27) was not detected. But it isn’t necessary that person not having this antigen isn’t suffering from autoimmune condition. While, someone having HLA-B27 antigen might not develop these conditions.
- Mostly the certainty of HLA antigens being present is dependent upon genes. Whether parents will pass these genes to their children will control production of the antigen.
WHY GET TESTED?
To determine whether you have human leukocyte antigen B27 (HLA-B27) on the surface of your cells; to help assess the likelihood that you have an autoimmune disorder associated with the presence of HLA-B27
