Introduction
Your immune system needs a way to tell which cells belong in your body (“self”) and which do not (“non-self”), such as viruses, bacteria, or transplanted organs. The Human Leukocyte Antigen (HLA) genes help do exactly that. Located in a special region called the Major Histocompatibility Complex (MHC) on chromosome 6, these genes create proteins that act like tiny display cases on each cell. They show bits of proteins (called peptides) to your immune cells so your body can decide whether to attack or leave them alone.
Glossary:
- Peptide: A small piece of protein.
- Allele: A version of a gene.
- Chromosome: A package of DNA carrying genes.
Why HLA Genes Are So Variable
There are thousands of HLA gene versions (alleles). This variety helps our population recognize many different germs. But some versions can also make you more likely to develop autoimmune diseases — conditions where your immune system mistakenly attacks your own body.
How HLA Works in Everyday Language
HLA and Autoimmune Diseases
Certain HLA versions increase the risk of specific autoimmune conditions:
- Type 1 Diabetes: Often linked to HLA-DR3 or DR4.
- Rheumatoid Arthritis: Related to certain HLA-DRB1 alleles.
- Celiac Disease: Almost all people with celiac carry HLA-DQ2 or DQ8.
- Ankylosing Spondylitis: Common in people with HLA-B27.
When the wrong protein bits are shown, your immune system can attack healthy tissue, causing chronic inflammation and damage.
HLA and Organ Transplants
When you receive an organ transplant, doctors match your HLA types as closely as possible to the donor’s. A close match lowers the chance your body will reject the new organ.
HLA and Body Odor (Pheromones)
Studies suggest that people may unconsciously prefer the scent of those with different HLA types. This helps promote genetic diversity in offspring, strengthening their immune systems.
Signs You Might Have a Risky HLA Type
Having a “high-risk” HLA allele does not guarantee disease — but you may notice:
- Persistent fatigue or low energy
- Frequent inflammation (joint pain, stomach issues)
- More infections than usual
- Allergic or drug reactions
What You Can Do to Lower Your Risk
Although you can’t change your genes, you can influence how they behave:
Conclusion
Your HLA genes play a central role in keeping you healthy — or, if certain versions are present, contributing to disease. By understanding your HLA type (through genetic testing) and adopting healthy lifestyle habits, you can support your immune system and reduce the risk of autoimmune issues.