Objectives To examine the possible correlations between the genetic background and clinical characteristics of the disease in patients with systemic lupus erythematosus (SLE).

Methods Distributions of MHC II Class (DRB1, DQA1 and DQB1) alleles were studied with molecular genetic methods (polymerase chain reaction and restriction fragment length polymorphism) in 50 SLE patients and 50 healthy blood donors as controls. The statistical significance of differences between the examined groups were analysed with Fisher’s exact test.

Results In our SLE patients, the DR2 (1501 subtype) – DQA1 0102 – DQB1 0602 (p = 0.045), the DR3 – DQA1 05011 – DQB1 0201 (p = 0.022), and the DR7 – DQA1 0201 – DQB1 0202 (p = 0.005) haplotypes occurred significantly more frequently than in controls. Evaluating the connexion between the genetic and clinical characteristics of the disease, we found that DR2 positivity was less frequent in patients with lupus nephritis (LN) than in those without LN (3/16 vs 16/34, p = 0.05). In contrast, DR3- and DR7-associated haplotypes were more common in LN than in patients without renal manifestation (8/16 vs 11/34 and 7/16 vs 8/34, respectively). In patients with pericarditis and/or pleuritis, DR7 positivity was more frequent than in patients without serositis (12/27 vs 3/23, p = 0.016). Similarly, the DR7-associated haplotype was detected more frequently in patients with one or more severe (renal, cardiopulmonary, central nervous system) manifestations as compared to patients without these major features (15/36 vs 0/14, p = 0.002).

Conclusion We conclude that there are three different MHC II Class haplotypes of susceptibility in Hungarian patients with SLE. In our experience, the DR7-positive cases exhibited more severe disease manifestations, while patients with DR2-positivity had a milder clinical course.