Specific tissue types predisposing to specific autoimmune diseases
Expansion
| HLA | Disease |
|---|---|
| B27 | Ankylosing spondylitis, reactive arthritis, psoriatic arthritis, inflammatory bowel arthritis, anterior uveitis |
| DQ2 and DQ8 | Coeliac disease |
| DR3 | Type 1 diabetes, Graves’, Addison’s, Sjogren’s, lupus, myasthenia |
| DR4 | Type 1 diabetes, rheumatoid arthritis |
| DR2 (DQB1*06:02) | Narcolepsy, Goodpasture’s, multiple sclerosis |
| B57:01 | Abacavir hypersensitivity |
| B*15:02 | Carbamazepine induced Stevens-Johnson syndrome |
| A3 | Haemochromatosis |
“B27 for PAIR”: Psoriatic arthritis, Ankylosing spondylitis, Inflammatory bowel disease arthritis, Reactive arthritis. These are the seronegative spondyloarthropathies, which share axial involvement, enthesitis, dactylitis and uveitis.
Two associations are directly actionable in prescribing: HLA-B*57:01 must be tested before abacavir, and HLA-B*15:02 before carbamazepine in patients of South East Asian ancestry.
Association is not causation, and not a diagnostic test: around 8 per cent of the UK population carries B27 while ankylosing spondylitis affects under 1 per cent, so a positive result in an unselected patient means very little.
DQ2 and DQ8 in coeliac disease are useful for the opposite reason: their absence essentially excludes the diagnosis.