HLA associations in juvenile arthritis

This review of the current status of HLA associations in juvenile arthritis begins with a discussion of the terms used to identify these patients and an approach for their clinical classification. The authors suggest that seven different types should be identified on the basis of clinical features and associated immunogenetic factors and that each of them should be recognized and called by a separate name. Different combinations of patients have been included in the studies performed in different cities and this fact may explain some of the observed differences in HLA associations in various reports. Results from an on-going study in Dallas are compared with published reports from Prague, Cincinnati, and Houston. HLA alleles associated with susceptibility in pauciarticular patients include certain DR and DQ alleles, one DP allele (DPB1*0201) and one HLA class I allele (HLA-A*0201). Susceptibility for polyarticular onset disease was found by the authors to be uniquely associated with DPB1*0301. Important interactions were observed between alleles at the different loci, with markedly increased odds ratios when combinations of susceptibility alleles were analyzed. The possibility that interaction between class I and class II susceptibility factors might be due to the effect of an allele at one of the TAP loci was examined by probing for polymorphic variants of the TAP1 and TAP2 genes. In addition, class I alleles associated with resistance for the development of juvenile arthritis were discussed. The main allele associated with rheumatoid arthritis (DRB1*0401) appears to be protective for the development of several forms of arthritis prevalent in children.