HLA-B27: subtypes related to autoimmune diseases

Test for HLA-B27 allele subtypes associated with autoimmune inflammatory diseases of the spine, spine and sacroiliac joints, known as spondyloarthropathies, such as ankylosing spondylitis.


On request, depending on the test

Time to result

On request, depending on the test

What is the HLA-B27 allele and what is its relationship to disease?

HLA-B27 allele and its relationship to autoimmune diseases

The HLA-B27 allele is a variant of the HLA gene that has been associated with several rheumatic diseases collectively known as spondyloarthropathies, most notably ankylosing spondylitis.

About 90% of patients with ankylosing spondylitis have some subtype of the HLA-B27 allele, i.e. they are HLA-B27 positive.

Other related autoimmune diseases are juvenile rheumatoid arthritis (80% of patients), and Reiter’s syndrome or reactive arthritis (50-80%). HLA-B*27 subtypes are also present in 50% of patients suffering from spondylitis along with other pathologies such as inflammatory bowel disease or psoriasis vulgaris. It should be clear that the HLA-B27 allele is not the cause of these pathologies, but its prevalence is higher in affected patients.

Detección del alelo HLA-B27

At Genosalut we offer a test that can detect all subtypes of the HLA-B27 allele.

We use the qPCR-HRM technique to detect the HLA-B27 allele. It is a high-resolution technique, with high sensitivity (100%), specificity (100%) and reproducibility.

The assay has been validated by Sanger sequencing.

Our value proposal


At Genosalut, we have more than 10 years of experience in counselling people with conditions where a genetic cause has been identified or is thought to be possible.


We are a close laboratory, we respond personally and we take the time to explain the report in detail to doctors and patients.

Professional interpretation of results

Because of our knowledge and experience, we are able to accurately interpret genetic results and offer professional advice.

Reference in the field

We are the point of contact for patients, doctors and clinics in all areas of human genetic diagnostics and prevention.

HLA gene: function, alleles and subtypes

What is the HLA complex or HLA system?

The human leukocyte antigen (HLA) system or complex is a complex of genes on chromosome 6 of humans that encode cellular surface proteins responsible for the regulation of the immune system. HLA is the human version of the major histocompatibility complex (MHC), a family of genes that occurs in many species. The genes of this complex are classified into three groups: class I, class II and class III. In humans, the HLA-B gene and two related genes, HLA-A and HLA-C, are the major MHC genes class I

What is the function of the HLA complex proteins?

The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders, such as viruses and bacteria. In other words, they are part of our defense system.
MHC class I genes provide instructions for making proteins that are present on the surface of almost all cells. On the cell surface, these proteins bind to protein fragments (peptides) that have been exported from inside the cell. MHC class I proteins display these peptides to the immune system. If the immune system recognizes the peptides as foreign (such as viral or bacterial peptides), it responds by causing the infected cell to self-destruct.

What are the alleles and subtypes of the HLA genes?

The HLA-B gene is a highly variable sequence, that is, there are notable differences between individuals. This variety allows each person's immune system to react to a wide range of foreign invaders. Hundreds of versions (alleles) of the HLA-B gene are known, each of which is assigned a certain number (such as HLA-B27). Closely related alleles are classified together; for example, more than 160 very similar alleles are subtypes of HLA-B27. These subtypes are designated as HLA-B*2701 to HLA-B*27160.
The HLA-B*27 allele is related to autoimmune inflammatory diseases of the spine, spine and sacroiliac joints, known as spondyloarthropathies, such as ankylosing spondylitis.

How can I request a genetic test for HLA-B27?
Request an appointment

Contact us through the form, by e-mail or by telephone to make an appointment with us.

Ask your physician

You can also consult your doctor for information on the possibilities of genetic testing.

We analyse the probe

In our genetic diagnostics laboratory we analyse the sample with the latest technology.

We write a report

We provide a detailed description of the results and, if necessary, genetic counselling.


With genetic testing it is possible to classify HLA-B27 alleles into different subtypes. To date, more than 160 different subtypes have been described.

It is not yet known how the individual subtypes affect the likelihood of developing an autoimmune disease.

This test is usually performed in people presenting with acute or chronic pain and inflammation in the back, neck, chest, eyes or joints, when there is suspicion of an autoimmune disease associated with the presence of the HLA-B27 allele. It is also sometimes requested to evaluate cases of recurrent uveitis.

HLA-B27 testing is primarily used to confirm a suspected diagnosis of ankylosing spondylitis, juvenile rheumatoid arthritis, reactive arthritis and some cases of anterior uveitis.

It should be made clear that the HLA-B27 test is not diagnostic for any disease and cannot be used to diagnose or rule out disease. It should be used and evaluated in conjunction with the patient’s signs and symptoms and other laboratory tests to diagnose or rule out a range of autoimmune diseases.

As mentioned above, this is not a diagnostic test. Evaluation of the symptoms and the results of other tests are necessary to be able to determine the possible disease. 

That is, if the test result is positive and the person has symptoms such as chronic joint pain, inflammation or degenerative bone changes (visible on X-rays), it is very likely that he/she has an autoimmune disease associated with HLA-B27 (ankylosing spondylitis, Reiter’s syndrome, reactive arthritis…) The probability is higher if it is a young man who starts to have symptoms before the age of 40.

However, being HLA-B27 positive does not imply that you will develop these diseases. 

If the result is negative, it means that the marker is not in the cell. However, the presence of the disease cannot be ruled out, as some people can develop autoimmune diseases even if they do not have the HLA-B27 allele. 

Most of the time the cause is not known. However, in some reactive arthritis there is an association between the development of the disease and a previous infection with microorganisms such as Chlamydia, Campylobacter, Salmonella, Ureaplasma or Yersinia. It is thought that the similarities between HLA-B27 and the antigens present on the surface of these micro-organisms may trigger the immune system to attack both the micro-organism and its own tissues, leading to autoimmune disease once the infection has resolved.

It is an inflammatory disease that mainly affects the joints of the spine, which tend to weld together, decreasing their flexibility and producing a stiffness of the spine. It is one of a group of rheumatic diseases called spondyloarthropathies.

The cause of the disease is unknown, although genes appear to play a role. Most people with ankylosing spondylitis (about 90%) are positive for the HLA-B27 allele.

Reiter’s syndrome, also known as reactive arthritis, is a condition ranging from an inflammatory reaction to an infection somewhere in the body. It usually follows an infection of the urinary tract, genital tract or digestive tract.
The following parts of the body may be affected:

  • Eyes causing conjunctivitis and/or uveitis
  • Joints leading to reactive arthritis
  • Urethr
  • Skin 

Although the exact origin of this disease is unclear, apart from urinary tract infections and intestinal infections caused by food poisoning, the presence of the HLA-B27 allele has also been associated with this disease.

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First genetic diagnosis laboratory in the Balearic Islands

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