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Autoimmune Diseases

Genetic factors behind autoimmune conditions. Explore HLA genes and other variants linked to celiac disease, Crohn's disease, rheumatoid arthritis, psoriasis, and more.

21 articles

Autoimmune diseases occur when the immune system mistakenly attacks the body's own tissues, and genetics plays a central role in determining who is susceptible. Over 80 autoimmune conditions have been identified, collectively affecting approximately 5–8% of the global population, with a strong hereditary component that makes genetic testing increasingly valuable for early detection and prevention.

The human leukocyte antigen (HLA) system is by far the most significant genetic region for autoimmune disease risk. Located on chromosome 6, the HLA genes encode proteins that present antigens to the immune system, essentially teaching it to distinguish "self" from "foreign." Specific HLA variants dramatically increase disease risk: HLA-DQ2 and HLA-DQ8 are present in virtually 100% of celiac disease patients (though only 30–40% of carriers develop the disease), HLA-B27 confers a 20–80× increased risk of ankylosing spondylitis, and HLA-DRB1 shared epitope alleles are the strongest genetic risk factor for rheumatoid arthritis.

Beyond HLA, genome-wide association studies (GWAS) have identified hundreds of non-HLA variants contributing to autoimmune susceptibility. The PTPN22 gene variant R620W (rs2476601) increases risk for type 1 diabetes, rheumatoid arthritis, lupus, and autoimmune thyroid disease — making it one of the most pleiotropic autoimmune variants known. CTLA-4 variants affect T-cell regulation and are linked to Graves' disease and type 1 diabetes. IL-23R variants provide protection against Crohn's disease and psoriasis, demonstrating that genetics can reveal both risk and resilience.

One of the most practical applications of autoimmune genetics is celiac disease screening. Since HLA-DQ2/DQ8 testing has a near-perfect negative predictive value, a negative result essentially rules out celiac disease, potentially saving years of unnecessary dietary restriction and invasive testing. Similarly, understanding your TNF-alpha and IL-6 genetic variants can inform your inflammatory baseline and guide anti-inflammatory lifestyle interventions.

By exploring your autoimmune-related genetic variants through Ask My DNA, you gain insight into your immune system's tendencies and can work with your healthcare provider on targeted screening schedules and evidence-based prevention strategies.

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