The frequencies of DNA fragments associated with the following HLA class II genes were increased in PJRA when compared to normal controls: DRB1*08 (DRw8) (35.2% vs 10.3%, RR = 4.6, p less than 10(-3), DRB3*01/02/03 (DRw52) (76.3% vs 48.1%, RR 3.5, p less than 10(-3)), DQA1*0401 (41.0% vs 7.4%, RR = 7.9, p less than 10(-3)), DQA1*0501 (55.6% vs 29.7%, RR = 3.0, p less than 10(-2), DQB1*0301 (DQw7) (46.2% vs 17.5%, RR = 4.0; p less than 10(-2)), DPA1*0201 (44.2% vs 7.9%, RR = 8.7, p less than 10(-5)), and DPB1*02 (DPw2) (40.7% vs 7.1%, RR = 8.5, p less than 10(-6)).
The difference persists with stratification, at least for DR5(11) and DPB1*0201, suggesting that this effect is unlikely to be due to linkage disequilibrium with HLA alleles known to be associated with early onset pauciarticular JRA.