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Has your doctor recommended the HLA-B27 test? The name might sound complex at first, but this genetic test plays a key role in diagnosing certain chronic inflammatory conditions—especially those affecting the spine and joints. It’s a simple blood test that can reveal a genetic predisposition to conditions such as ankylosing spondylitis and reactive arthritis, allowing for early intervention and personalized treatment.In this medical guide from Dalili Medical, we’ll walk you through everything you need to know about the HLA-B27 test:
✅ What is it?
✅ When is it requested?
✅ How is it done?
✅ What do the results mean?
✅ And how is it connected to autoimmune and inflammatory diseases?

✅ What is the HLA-B27 Test?

The HLA-B27 test is a blood test that detects the presence of a specific gene known as HLA-B27 (Human Leukocyte Antigen B27). This gene belongs to a group of genes responsible for regulating the immune system's response.
Having this gene does not necessarily mean you have a disease, but it’s linked to an increased risk of developing certain autoimmune and inflammatory conditions.

❓ Why is the HLA-B27 Test Ordered?

Doctors usually request this test when there's a suspicion of autoimmune-related inflammation. Common situations include:

Suspected Ankylosing Spondylitis
Persistent lower back pain and morning stiffness
Suspected Reactive Arthritis after a bacterial infection
Eye inflammation such as uveitis
Psoriatic arthritis
Inflammatory bowel disease (Crohn’s or ulcerative colitis) with joint symptoms

???? How is the HLA-B27 Test Done?

A venous blood sample is taken from your arm.
No fasting is required.
Results are usually available within a few days to a week, depending on the lab.

???? What Do HLA-B27 Results Mean?

1. Positive HLA-B27 Result

Indicates that the HLA-B27 gene is present.
It does not confirm a diagnosis but increases the risk of certain autoimmune conditions.
For example, about 90–95% of people with ankylosing spondylitis are HLA-B27 positive.

2. Negative HLA-B27 Result

Indicates that the gene is not present.
Reduces the likelihood of certain diseases but does not rule them out entirely.

???? Diseases Associated with HLA-B27

Disease	Association with HLA-B27
Ankylosing Spondylitis	90–95%
Reactive Arthritis	70–80%
Acute Anterior Uveitis (eye inflammation)	50%
Psoriatic Arthritis	<25%
IBD with Arthritis (Crohn’s, UC)	10–20%

Note: Carrying the HLA-B27 gene helps guide diagnosis but does not guarantee disease development.

???? HLA-B27 vs. Other Diagnostic Tests

Test	Purpose
HLA-B27	Identifies genetic susceptibility
CRP / ESR	Measures inflammation levels
ANA	Screens for lupus and related disorders
RF & Anti-CCP	Detects rheumatoid arthritis

⚠️ Symptoms That May Require HLA-B27 Testing

You may be advised to do the HLA-B27 test if you experience:

Chronic lower back or hip pain with morning stiffness
Recurrent eye inflammation (e.g., uveitis)
Sudden joint swelling (knees, ankles)
Heel or foot pain
Family history of autoimmune joint disease

❓ Does Having HLA-B27 Mean You Have a Disease?

No. A positive HLA-B27 result means you are genetically predisposed, but diagnosis depends on:

Symptoms and clinical signs
MRI scans or imaging
Inflammatory markers
Evaluation by a rheumatologist

???? Is HLA-B27 Inherited?

Yes, the gene is passed down through families.

If one parent carries the gene, the child is more likely to inherit it.
However, routine screening is not recommended unless symptoms are present.

???? Does HLA-B27 Affect Treatment?

Yes. If a condition like ankylosing spondylitis is diagnosed:

Early treatment is crucial.
Doctors may prescribe:
- NSAIDs for pain and stiffness
- Biologic therapies (e.g., TNF inhibitors)
The presence of HLA-B27 may help tailor a personalized treatment plan.

???? Frequently Asked Questions (FAQs)

Q: Can I have the disease even if the test is negative?
A: Yes. Some patients may test negative but still develop the disease.

Q: Do I need to fast before the test?
A: No. The test requires no fasting or special preparation.

Q: Is the test repeated?
A: Usually not. It’s a genetic test that’s done once in a lifetime.

Q: Should my family members be tested?
A: Not unless they have symptoms. Carrying the gene without symptoms is not a cause for concern.

✅ Summary

The HLA-B27 test is a simple yet powerful tool that helps doctors diagnose autoimmune inflammatory diseases, especially ankylosing spondylitis and reactive arthritis.
Having the gene doesn't mean you're sick, but it helps guide early diagnosis and intervention when symptoms appear.