Prevalence of HLA-DR4 in children with chronic arthritis

Among children with juvenile rheumatoid arthritis (JRA), the proportion of the study population with the HLA-DR4 allele is shown by disease-onset type (top graph) and by sex (bottom). The horizontal line shows the frequency of the allele in the control group. HLA-DR4 was less common than in controls in younger males and patients with oligoarticular disease and more common than in controls in older children with polyarticular disease.