Patients with pauciarticular and polyarticular onset rheumatoid factor (RF) negative juvenile arthritis (JA) have been reported to have a variety of HLA associations. The reason for the differences found in several recent studies is not known. We compare a new series of patients investigated in Prague, Czechoslovakia with those we reported from Dallas.
Czech patients with JA (N = 153) were classified clinically using the same criteria as in our studies in Dallas. The RF negative group included 56 patients that had persistent pauciarticular disease, 42 pauciarticular with polyarticular course and 39 with polyarticular onset. RF was present in 13 additional patients. HLA class II alleles were determined by oligotyping as previously described from our laboratory.
DRB1*0801 was increased and DRB1*0701 was decreased in all the RF negative groups. The persistent pauciarticular group was associated with DRB1*11 and DPB1*0201 and lacked the association with DRB1*1301 seen in Dallas. Also found in Prague and not in Dallas were an increase in the frequency of DR2 in pauciarticular patients with early conversion and of DRB1*1201 in patients with iritis. Certain HLA associations (DRB1*0801, DPB1*0201) appear to be present in patients with JA in most studies; others (DRB1*1301, DPB1*0301) are more variable.
The reason for differences in the HLA risk factors observed in our 2 populations is not known. Clinical heterogeneity not detected by our method seems the most likely explanation. Genetic and environmental factors may also play a role.