Meyahealth
Home
ENES
HomeGeneticsGeneHLA-B gene
Back to Gene
HLA-B gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

HLA-B gene

The HLA-B gene is a key component of the immune system that helps the body distinguish its own proteins from those of foreign invaders like viruses and bacteria.

Normal Function

The HLA-B gene provides instructions for making a protein that is part of the human leukocyte antigen (HLA) complex. This complex is the human version of the major histocompatibility complex (MHC). HLA-B, along with HLA-A and HLA-C, belongs to the MHC class I group.

MHC class I proteins are present on the surface of almost all cells. They bind to protein fragments (peptides) exported from within the cell and display them to the immune system. If the immune system recognizes these peptides as foreign, it triggers the infected cell to self-destruct. The HLA-B gene has hundreds of variations (alleles), allowing the immune system to react to a wide range of foreign invaders.

Health Conditions Related to Genetic Changes

Ankylosing spondylitis

Variants in the HLA-B gene, particularly HLA-B27, significantly increase the risk of ankylosing spondylitis, a chronic inflammatory arthritis primarily affecting the spine. Researchers speculate that HLA-B27 may abnormally display peptides that trigger an immune reaction, or that the protein may misfold, leading to inflammation. While HLA-B27 increases risk, most people with this variant never develop the disorder.

Behçet disease

The HLA-B51 variant is associated with an increased risk of Behçet disease, a chronic inflammatory condition. This association is strongest in individuals from Japan, the Middle East, and other parts of Asia.

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN)

Certain HLA-B variations are linked to an increased risk of SJS/TEN, a life-threatening skin reaction often triggered by medications:

  • HLA-B*1502: Increases risk when taking certain seizure medications, such as carbamazepine.
  • HLA-B*5801: Increases risk when treated with allopurinol.

These variations cause the immune system to react abnormally to medications, triggering the release of granulysin, which destroys skin and mucous membrane cells.

Other disorders

  • Spondyloarthropathies:HLA-B27 is associated with inflammatory joint diseases, including reactive arthritis and conditions related to psoriasis or inflammatory bowel disease.
  • Abacavir Hypersensitivity: In HIV-positive individuals, HLA-B*5701 increases the risk of a hypersensitivity reaction to the drug abacavir.
  • HIV/AIDS Progression:HLA-B27 and HLA-B57 are associated with slower progression to AIDS, while HLA-B35 is associated with faster progression.
  • Malaria:HLA-B53 has been shown to help protect against severe malaria in West African populations.

Other Names for This Gene

  • 1B07_HUMAN
  • HLA class I histocompatibility antigen, B alpha chain
  • leukocyte antigen B
  • MHC class I HLA-B heavy chain

Frequently Asked Questions

positive HLA‑B27 result indicates a higher genetic risk for ankylosing spondylitis and related spondyloarthropathies, but it does not guarantee that you will develop the disease. Many people with HLA‑B27 never develop symptoms, so regular monitoring and early evaluation of back pain or stiffness are recommended.
Maintaining a regular exercise routine that includes stretching and strengthening, avoiding smoking, and managing body weight can help reduce inflammation and improve spinal mobility. If early symptoms appear, prompt medical evaluation and early treatment with NSAIDs or biologic agents can slow disease progression.===
The HLA‑B*1502 allele is strongly linked to a life‑threatening skin reaction called Stevens‑Johnson syndrome or toxic epidermal necrolysis when taking drugs like carbamazepine, phenytoin, or certain antiepileptics. Testing before prescription can prevent exposure to these high‑risk medications in susceptible patients.
Certain HLA‑B alleles, especially HLA‑B51, are associated with an increased risk of Behçet disease, particularly in people of Asian or Middle Eastern descent. If you carry HLA‑B51 and have unexplained mouth or genital ulcers, eye inflammation, or skin lesions, you should discuss evaluation with a rheumatologist.
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.

Meyahealth

Ⓒ 2026. All rights reserved by MEYA

About UsTerms & PolicyFAQ