HLA as an immunogenetic risk factor in juvenile chronic arthritis.

We investigated the frequencies of HLA-A, -B, -C and -DR antigens in diseased and control group with the aim to find immunogenetic factors that influence the pathogenesis and clinical course of juvenile chronic arthritis (JCA). The study was conducted on 73 JCA patients, 24 boys and 49 girls. On the basis of observed HLA antigen frequencies the relative risks (RR) and their statistical significance as well as the attributable risks (delta) were calculated. In the group of 73 JCA children the only statistically significant finding was a decreased RR for DR7. When the calculations were performed on boys taken from the JCA group, significantly higher RR were found for DR5, B27, B40 and A32. Further analysis was performed on clinically defined subgroups of JCA. In 15 children with pauciarticular persistent arthritis significantly increased RR and delta were found for A25, DR2 and DR3. No significant RR were observed in a subgroup of 44 sero-negative polyarticular arthritis. When only boys of this subgroup were selected for calculations, significantly increased frequencies were found for antigens A32, B40, DR1 and DR5. The reason for a stronger association of immunogenetic risk factors in diseased males than females is discussed.