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HLA-DRB1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

HLA-DRB1 gene

The HLA-DRB1 gene is a key component of the immune system, helping the body identify foreign invaders and playing a significant role in various autoimmune conditions.

Overview

The HLA-DRB1 gene provides instructions for the beta chain protein, which binds to the alpha chain (produced by the HLA-DRA gene) to form the HLA-DR antigen-binding heterodimer. This protein complex presents foreign peptides to the immune system, triggering an attack against viruses and bacteria.

There are hundreds of alleles of the HLA-DRB1 gene. This genetic diversity allows the immune system to respond to a wide range of pathogens. However, certain variations can lead the immune system to mistakenly target the body's own proteins, contributing to autoimmune diseases.

Health Conditions Related to Genetic Changes

Autoimmune Addison disease

This condition occurs when the immune system attacks the adrenal glands. The HLA-DRB1*04:04 allele is a well-known risk factor. The immune response is often triggered by the protein 21-hydroxylase, leading to a shortage of adrenal hormones.

Multiple sclerosis (MS)

Certain HLA-DRB1 alleles influence the risk of MS, a condition characterized by damage to the brain and spinal cord. The HLA-DRB1*15:01 allele is associated with an increased risk of developing the disease.

Rheumatoid arthritis

Variations in HLA-DRB1 are the most significant known genetic risk factor for rheumatoid arthritis. The HLA-DRB1*04 and HLA-DRB1*01 alleles are strongly associated with high risk. These alleles produce beta chains containing a specific sequence called the "shared epitope," which makes the protein more likely to bind to the body's own proteins rather than foreign ones, triggering an abnormal immune response.

Type 1 diabetes

Risk is influenced by combinations of HLA-DRB1 with HLA-DQA1 and HLA-DQB1. The highest risk is associated with the DR3 and DR4 haplotypes:

  • DR3:DRB1*03:01-DQA1*05:01-DQB1*02
  • DR4:DRB1*04:01/02/04/05/08-DQA1*03:01-DQB1*02

Other autoimmune disorders

HLA-DRB1 alleles have been linked to other autoimmune conditions, including pemphigus (severe skin blistering) and sarcoidosis (inflammation in multiple organs).

Frequently Asked Questions

For Multiple Sclerosis (MS), early signs might include unexplained numbness, tingling, vision problems (like blurred or double vision), balance issues, or severe fatigue. For Rheumatoid Arthritis (RA), watch for persistent joint pain, stiffness (especially in the morning), swelling, and tenderness, often affecting smaller joints symmetrically. For Type 1 Diabetes, increased thirst, frequent urination, unexplained weight loss, and fatigue are key indicators. For Autoimmune Addison disease, symptoms can include chronic fatigue, muscle weakness, weight loss, loss of appetite, and dark patches on the skin.
No, having an HLA-DRB1 allele linked to an autoimmune disease, such as HLA-DRB1*15:01 for multiple sclerosis or HLA-DRB1*04 for rheumatoid arthritis, means you have an increased genetic predisposition or risk. It does not guarantee you will develop the condition. Autoimmune diseases are complex and result from a combination of genetic, environmental, and other factors. Many people with these risk alleles never develop the associated disease.
Yes, while genetics play a role, environmental and lifestyle factors are believed to interact with HLA-DRB1 risk alleles to trigger autoimmune diseases. For example, smoking is a known risk factor for rheumatoid arthritis, particularly in those with specific HLA-DRB1 alleles. Infections, vitamin D deficiency, gut microbiome imbalances, and certain medications or toxins are also being investigated for their potential roles in triggering autoimmune conditions in genetically predisposed individuals.
HLA-DRB1 genetic testing is not typically used for routine diagnosis of autoimmune diseases, as the presence of a risk allele doesn't confirm the disease, and its absence doesn't rule it out. However, it can be useful in specific situations, such as confirming a diagnosis in ambiguous cases, assessing disease prognosis, or identifying individuals at higher risk within families. For example, in rheumatoid arthritis, certain HLA-DRB1 alleles are associated with more severe disease or a poorer response to some treatments.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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