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HLA-DR genotype risks in seropositive rheumatoid arthritis
Insights
Rheumatoid arthritis (RA) risk is linked to specific human leukocyte antigen (HLA) genes, particularly DR4. Homozygous DR4 carriers face a higher risk, and DR3 is associated with gold salt toxicity.
Area of Science:
- Immunogenetics
- Rheumatology
- Human Leukocyte Antigen (HLA) complex
Background:
- Rheumatoid arthritis (RA) is an autoimmune disease with a known genetic component.
- Human Leukocyte Antigen (HLA) genes are crucial for immune response and have been implicated in autoimmune diseases.
- Previous studies suggest an association between specific HLA antigens and RA susceptibility.
Purpose of the Study:
- To investigate the distribution of HLA-A, B, C, and -DR antigens in Caucasian RA patients.
- To determine the association of specific HLA-DR genotypes with RA risk and disease characteristics.
- To explore the relationship between HLA antigens and toxic complications from gold salt treatment.
Main Methods:
- Genotyping of HLA-A, B, C, and -DR antigens in 77 Caucasian sero-positive RA patients.
- Comparison of patient genotypes with a control panel of 110 unrelated Caucasian donors.
- Statistical analysis to assess antigen frequencies, genotype risks, and associations with disease onset and treatment complications.
Main Results:
- Confirms the association of HLA-DR4 with RA.
- Identifies increased disease risk for patients carrying HLA-DR1, -DR2, and -DR3.
- Reveals a higher risk for DR4/4 homozygotes compared to heterozygotes (DR4/1, DR4/2, DR4/3).
- Suggests DR4 is more frequent in early-onset RA (before age 35).
- Shows a significant excess of HLA-DR3 in patients experiencing toxic reactions to gold salts.
Conclusions:
- Specific HLA-DR genotypes significantly influence rheumatoid arthritis susceptibility and risk.
- The observed genotype risks support the inheritance of a single, linked genetic determinant for RA.
- HLA-DR3 positivity is a potential marker for adverse reactions to gold salt therapy in RA patients.
Abstract:
We studied the distribution of HLA-A, B, C, and -DR antigens in 77 Caucasian patients with sero-positive rheumatoid arthritis. Forty-four patients were genotyped and compared with the control panel of 110 unrelated Caucasian genotyped donors. The data obtained confirm the association of DR4 with RA, and reveal an increased risk of disease for patients carrying DR1, DR2, and DR3, compared to the risk for those carrying other antigens, such as DR5, DRw6, and DR7. There is a higher risk for DR4/4 homozygotes than for DR4/1, DR4/2, or DR4/3 heterozygotes. DR4/5, DR4/6, and DR4/7 have a lower risk than the previously mentioned genotypes. The genotype risks are compatible with the inheritance of a single, linked genetic determinant of disease susceptibility, but we are unable to distinguish between recessive and dominant inheritance of susceptibility using the "antigen-frequencies-amongst-diseases" method. DR4 seems to be more frequent in patients in whom onset occurs before the age of 35 (79% vs. 54% DR4 positive). A significant excess of DR3 + is observed in patients with toxic complications following treatment with gold salts (X2(1) = 8.96).