HLA Associations: High-Yield Board Review
Human Leukocyte Antigens (HLA) are essential for self-recognition and antigen presentation. Many autoimmune and inflammatory diseases exhibit strong associations with specific HLA alleles, which serve as high-yield “buzzwords” for clinical vignettes.
| HLA Allele | Associated Conditions |
|---|---|
| HLA-B27 | Psoriatic arthritis, Ankylosing spondylitis, Inflammatory bowel disease-associated arthritis, Reactive arthritis (PAIR). |
| HLA-DR3 | Diabetes mellitus type 1, SLE, Graves disease, Hashimoto thyroiditis, and Addison’s disease. |
| HLA-DR4 | Rheumatoid arthritis, Diabetes mellitus type 1. |
| HLA-DQ2 / DQ8 | Celiac disease (Strongest genetic association). |
| HLA-DR2 | Multiple sclerosis, Goodpasture syndrome, and hay fever. |
| HLA-B8 | Myasthenia gravis, Graves disease. |
High-Yield Exam Mnemonics & Pearls
- PAIR (B27): Use this to remember the seronegative spondyloarthropathies: Psoriatic arthritis, Ankylosing spondylitis, IBD-associated arthritis, and Reactive arthritis.
- Celiac (DQ2/DQ8): If a patient presents with iron deficiency anemia, diarrhea, and dermatitis herpetiformis, look for HLA-DQ2/DQ8 in the options.
- Goodpasture (DR2): Remember the “Goodpasture” is “2” (DR2) words long.
- Diabetes Type 1 (DR3/DR4): Patients who are DR3/DR4 positive are at significantly higher risk than those with only one.
Pathology Note: HLA genes are located on chromosome 6. They encode Class I molecules (A, B, C), which present to CD8+ T-cells, and Class II molecules (DR, DP, DQ), which present to CD4+ T-cells.