During the course of a workup for possible autoimmune arthritis or autoimmune back disease, your rheumatologist may order something called a HLA-B27 test. So what does a positive HLA-B27 mean?
HLA-B27 antigen
HLA-B27 is a genetic test. The majority of people who have a positive HLA-B27 are perfectly healthy. HOWEVER, having a positive HLA-B7 can put you at increased risk of developing what we call spondyloarthritis-associated diseases. This is a family of autoimmune diseases.
Spondyloarthritis-associated diseases
- Ankylosing spondylitis (AS), now called axial spondylitis
- Peripheral spondyloarthritis
- Reactive arthritis
- Psoriasis
- Psoriatic arthritis
- Uveitis
- Crohn’s disease
- Ulcerative colitis
I have a positive HLA-B27, what does it mean?
The answer to this question highly depends on your situation. As I mentioned earlier, many people who have a positive HLA-B27 are perfectly healthy. More specifically, the majority of these people do NOT have an autoimmune disease. Here are a few stats to put things into perspective.
- About 6 to 9 % of Caucasians and 3 % of African-Americans have a positive HLA-B27.
- However, having a positive HLA-B27 increases a person’s risk of ankylosing spondylitis by 50 to 100 times.
- But only 2 % of people who have a positive HLA-B27 go on to develop ankylosing spondylitis.
- About 50% of people with psoriatic arthritis that involves the spine have a positive HLA-B27.
- 60% of people diagnosed with reactive arthritis have a positive HLA-B27. These people tend to have more severe symptoms, non-joint symptoms (e.g., uveitis), and it tends to last longer.
- In the West, 50% of cases of anterior uveitis is associated with a positive HLA-B27 and about half of these people will develop spondyloarthritis.
I was diagnosed with AS, should I have my kids tested?
Technically not unless a family member is experiencing symptoms suggestive of ankylosing spondylitis, psoriatic arthritis, inflammatory bowel disease, or any other spondyloarthritis-associated disease. Remember, only 2% of people with a positive HLA-B27 go on to develop ankylosing spondylitis, which is the main autoimmune disease associated with this test.
However, people who have a positive HLA-B27 AND have a first-degree relative with ankylosing spondylitis have a 15% to 20% risk of developing the disease at some point during their lifetime.
I guess the answer whether to or whether not to test your kids really is a matter of choice. My opinion is, if it’s going to happen it’s going to happen. All we really can do is try to make healthy life choices like eating clean, staying active, reduce stress, and making sure we sleep enough. Remember the Blue Zones Principles?
For some people, knowing they tested positive for HLA-B27 may increase their stress level and for others not knowing whether they test positive or not may be more harmful. Whatever decision you make is highly personal.
In summary
Why having a HLA-B27 increases risk of having ankylosing spondylitis as well as a host of different autoimmune diseases is still uncertain: arthrogenic peptide hypothesis, molecular mimicry, free heavy chain hypothesis, and unfolded protein hypothesis. These are very complex concepts, which I will hold off on discussing further.
If you want to learn more about HLA-B27 and spondyloarthritis, I invite you to read the following articles: What is autoimmune back pain? Guide to living with psoriatic arthritis: part 1, and What is autoimmune joint pain?
If you think you may be suffering from a spondyloarthritis-associated condition, I encourage you to get in touch with your local rheumatologist. Here is a link to the American College of Rheumatology physician directory.
Medical Disclaimer
This information is offered to educate the general public. The information posted on this website does not replace professional medical advice, but for general information purposes only. There is no Doctor – Patient relationship established. We strongly advised you to speak with your medical professional if you have questions concerning your symptoms, diagnosis and treatment.
References
Rheumatology Secrets, 3rd edition