HLA-B27 Antigen

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Also known as: Ankylosing Spondylitis, HLAB27 Antigen

Hla-B27 Antigen

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The HLA-B27 Antigen test contains 1 test with 1 biomarker.

Brief Description: The Human Leukocyte Antigen B27 (HLA-B27) Antigen test is a genetic test that identifies the presence of the HLA-B27 antigen on the surface of white blood cells. This test plays a crucial role in diagnosing certain autoimmune disorders, particularly those involving the joints and spine.

Collection Method: Blood Draw

Specimen Type: Whole Blood

Test Preparation: No preparation required

When is an HLA-B27 Antigen test ordered?

When a patient experiences acute or persistent pain and inflammation in the spinal vertebrae, chest, neck, eyes, and/or joints, and the doctor feels the cause is an autoimmune illness linked to the existence of HLA-B27, an HLA-B27 test may be prescribed. When someone has recurrent uveitis, an HLA-B27 test may also be required.

When doctors suspect ankylosing spondylitis however the disease is in its early stages and the vertebrae in the spine have not yet developed the distinctive alterations that would be visible on X-ray, they usually employ the HLA-B27 test result.

What does an HLA-B27 Antigen blood test check for?

On the surface of cells, there is a particular protein called HLA-B27. The gene that produces the HLA-B27 protein is sometimes referred to as HLA-B27. The HLA-B27 test examines whether a person's white blood cells have the HLA-B27 protein on their surface or not.

Human leukocyte antigens are proteins that assist the immune system of the body in recognizing and differentiating between "self" and "nonself" cells. The many antigens found on each person's cell surfaces are encoded by an inherited mix of HLA genes. Each person has a unique HLA combination depending on the presence or absence of each antigen.

Approximately 6% of Americans have the HLA-B27 gene. Autoimmune conditions such ankylosing spondylitis, juvenile rheumatoid arthritis, reactive arthritis, and isolated acute anterior uveitis are more common in those with HLA-B27. Inflammatory bowel disease and a number of other chronic diseases have also been connected to HLA-B27.

Reactive arthritis and ankylosing spondylitis are two chronic, progressive diseases that affect males more frequently than women. The early 30s are the normal age when the first symptoms appear. It can take years for the typical degenerative changes to bones and joints to become obvious on X-rays, and the initial symptoms of these autoimmune illnesses are frequently mild.

  • Pain, inflammation, and a progressively hardening of the spine, neck, and chest are the hallmarks of ankylosing spondylitis.
  • A collection of symptoms known as reactive arthritis include skin rashes, urethral, ocular, and joint inflammation.
  • A type of arthritis that affects children is called juvenile rheumatoid arthritis.
  • Recurrent inflammation of the tissues in one or both eyes is a symptom of anterior uveitis.

There is a higher prevalence of the antigen in those who are affected, despite the fact that HLA-B27 has not been proven to be the cause of any of these ailments. For instance, 80–90% of persons with ankylosing spondylitis are HLA-B27 positive, despite the fact that only 6% of the general population carries this gene.

Lab tests often ordered with an HLA-B27 Antigen test:

When an HLA-B27 test is ordered, it's often part of a broader evaluation of rheumatologic and autoimmune conditions. Here are some tests commonly ordered alongside it:

  1. Erythrocyte Sedimentation Rate (ESR):

    • Purpose: To measure the rate at which red blood cells sediment in a period of one hour, an indirect measure of inflammation.
    • Why Is It Ordered: To assess the presence and degree of inflammation, which is common in conditions associated with HLA-B27.
  2. C-Reactive Protein (CRP):

    • Purpose: To detect inflammation and monitor its severity.
    • Why Is It Ordered: Like ESR, CRP is a marker of inflammation and can help in assessing the severity of the disease process.
  3. Complete Blood Count (CBC):

    • Purpose: To evaluate overall blood health.
    • Why Is It Ordered: To check for signs of anemia or other hematological changes that can occur with chronic inflammation and autoimmune disorders.
  4. Rheumatoid Factor (RF) and Anti-Cyclic Citrullinated Peptide (Anti-CCP) Antibodies:

    • Purpose: To test for markers associated with rheumatoid arthritis.
    • Why Is It Ordered: To differentiate between rheumatoid arthritis and other rheumatic diseases, such as those associated with HLA-B27.
  5. Antinuclear Antibodies (ANA):

    • Purpose: To screen for autoantibodies often present in autoimmune disorders.
    • Why Is It Ordered: To evaluate for other autoimmune conditions, as ANA is a marker for systemic lupus erythematosus and other autoimmune diseases.
  6. Kidney Function Test:

    • Purpose: To assess kidney function.
    • Why Is It Ordered: To monitor kidney health, as some autoimmune conditions and medications used to treat them can affect kidney function.

These tests, when ordered alongside an HLA-B27 test, provide a comprehensive assessment of potential autoimmune or inflammatory conditions. They are crucial for diagnosing conditions associated with HLA-B27, understanding the extent of the disease, and guiding treatment strategies. The specific combination of tests will depend on the individual’s symptoms, medical history, and the results of initial screenings.

Conditions where an HLA-B27 Antigen test is recommended:

The HLA-B27 Antigen test is particularly useful in diagnosing and monitoring the following conditions:

  • Ankylosing Spondylitis: This chronic inflammatory disease primarily affects the spine and sacroiliac joints. The presence of HLA-B27 is strongly associated with an increased risk of ankylosing spondylitis.

  • Reactive Arthritis: Also known as Reiter's syndrome, this condition involves joint inflammation that occurs in response to an infection, often of the gastrointestinal or genitourinary tract.

  • Juvenile Idiopathic Arthritis: Certain subtypes of juvenile idiopathic arthritis, particularly those involving the entheses (sites where tendons and ligaments attach to bones), are associated with HLA-B27 positivity.

How does my health care provider use an HLA-B27 Antigen test?

The HLA-B27 test is typically requested to support or confirm a suspected diagnosis of reactive arthritis, juvenile rheumatoid arthritis, ankylosing spondylitis, or occasionally anterior uveitis. The HLA-B27 test is non diagnostic, meaning that it cannot be used to provide a firm diagnosis or exclude a condition. The outcome provides additional information and is one piece of evidence that is utilized in conjunction with the assessment of signs, symptoms, and other laboratory tests to confirm or disprove the diagnosis of specific autoimmune illnesses, such as reactive arthritis and ankylosing spondylitis.

A series of tests, including the HLA-B27 test, may be requested to help identify and assess diseases that result in arthritis-like symptoms such chronic joint pain, feeling stiff, and inflammation. Rheumatoid factor testing using either an erythrocyte sedimentation rate or a C-reactive protein may be part of this set of tests. When evaluating a patient with recurrent uveitis that is not brought on by a known disease etiology, HLA-B27 may occasionally be requested.

What do my HLA-B27 test results mean?

A positive HLA-B27 test indicates that the subject is more likely to acquire specific autoimmune illnesses. Ankylosing spondylitis, arthritis, or another autoimmune illness linked to the presence of HLA-B27 may be diagnosed if the patient exhibits symptoms including chronic pain, inflammation, and/or degenerative changes to the bones. This is particularly true if the individual is young, male, and had his initial symptoms before to the age of 40.

A negative HLA-B27 test indicates that the marker was not found. However, as people without the HLA-B27 antigen can also develop various autoimmune disorders, this does not necessarily imply that the person who was tested does not have the suspected condition. The HLA-B27 antigen carries no guarantee that a person will experience any of these ailments. Researchers are attempting to identify the causes of these specific diseases as well as the variables that increase the risk of these diseases in people with HLA-B27.

Genetics determines whether or not specific HLA antigens will be present. The generation of those antigens is governed by genes that are passed down from parents to their offspring. Two HLA-B27 positive family members who experience the onset of one of the HLA-B27-related illnesses are more likely to experience the onset of the illness themselves.

Most Common Questions About the HLA-B27 Antigen test:

Understanding the HLA-B27 Antigen Test

What is the HLA-B27 Antigen test, and what is its primary function?

The HLA-B27 Antigen test identifies the presence of the Human Leukocyte Antigen B27 (HLA-B27) in the blood. This antigen is a protein found on the surface of white blood cells and is linked to certain autoimmune and inflammatory conditions, such as ankylosing spondylitis and reactive arthritis. The test helps in diagnosing these conditions or determining the risk of developing them.

What disorders are associated with the presence of the HLA-B27 antigen?

The presence of HLA-B27 is most commonly associated with ankylosing spondylitis but is also linked to other inflammatory disorders such as reactive arthritis, psoriatic arthritis, and inflammatory bowel disease-associated arthritis.

Interpretation of the HLA-B27 Antigen Test Results

What does a positive HLA-B27 Antigen test mean?

A positive HLA-B27 Antigen test indicates the presence of the HLA-B27 protein. It doesn't confirm a specific disease but is often found in patients with certain autoimmune disorders. It can help in the diagnostic process when symptoms are present.

Is it possible to have the HLA-B27 antigen but not have an associated disorder?

Yes, having the HLA-B27 antigen does not necessarily mean a person will develop an associated disorder. It is found in a small percentage of the general population without any related symptoms or conditions.

Can the HLA-B27 Antigen test be negative in someone with an associated disorder?

Yes, it is possible to have a negative HLA-B27 Antigen test and still have an associated disorder. The antigen is not present in all individuals with these conditions, so clinical evaluation and other diagnostic tests are also necessary.

Clinical Applications of the HLA-B27 Antigen Test

How is the HLA-B27 Antigen test used in the diagnosis of ankylosing spondylitis?

The HLA-B27 Antigen test is used in conjunction with clinical evaluation, medical history, and other diagnostic methods to diagnose ankylosing spondylitis. A positive result can support the diagnosis, especially if typical symptoms are present.

Can the HLA-B27 Antigen test be used for monitoring disease progression?

The HLA-B27 Antigen test is not typically used to monitor disease progression but can be part of the initial diagnostic workup. Monitoring usually relies on clinical assessment, imaging studies, and other specific tests.

What other tests might be used in conjunction with the HLA-B27 Antigen test?

Other tests that might be used with the HLA-B27 Antigen test include rheumatoid factor, anti-CCP antibodies, CRP, ESR, and imaging studies like X-rays or MRI, depending on the suspected condition.

Genetic Considerations and Family Connections

Is the presence of the HLA-B27 antigen hereditary?

Yes, the HLA-B27 antigen is inherited, and family members of an individual with the antigen might have an increased likelihood of having it themselves and potentially developing associated disorders.

Should family members be tested for the HLA-B27 antigen if a relative is positive?

Testing family members for the HLA-B27 antigen is usually not performed unless there are specific symptoms or clinical indications, as the presence of the antigen alone doesn't confirm a disorder.

Research and Special Populations

How is the HLA-B27 Antigen test used in research studies?

In research, the HLA-B27 Antigen test may be used to study the genetic basis of associated disorders, the function of the antigen itself, and the development of targeted therapies.

How is the HLA-B27 Antigen test relevant to populations with higher prevalence rates of the antigen?

In some populations, the HLA-B27 antigen is more prevalent. The test might be used more frequently in such populations to aid in diagnosing associated disorders.

Can the HLA-B27 Antigen test be used to study drug responses in individuals?

The HLA-B27 Antigen test may be relevant in pharmacogenomics to study drug responses, especially if targeted therapies for associated disorders are being developed or used.

Is the HLA-B27 Antigen test used in organ transplantation?

The HLA-B27 Antigen test may be used in the context of organ transplantation to match donors and recipients, as compatibility in HLA typing is important for successful transplantation.

How is the HLA-B27 Antigen test utilized in epidemiological studies?

In epidemiology, the HLA-B27 Antigen test can be used to study the prevalence and distribution of the antigen and its associated disorders in different populations.

What are the connections between HLA-B27 positive status and other immune-mediated diseases?

HLA-B27 positive status is not only linked to ankylosing spondylitis but also other immune-mediated diseases. Research is ongoing to understand these connections and how the antigen might contribute to disease mechanisms.

Can the HLA-B27 Antigen test be used as a screening tool in asymptomatic individuals?

The HLA-B27 Antigen test is not typically used as a screening tool in asymptomatic individuals, as the presence of the antigen alone is not diagnostic of any specific disease.

How does the HLA-B27 Antigen test contribute to the field of personalized medicine?

The HLA-B27 Antigen test can contribute to personalized medicine by aiding in early diagnosis, predicting disease risk in susceptible individuals, and potentially guiding targeted therapies for associated disorders.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.

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