Increased frequency of TAP2B in early onset pauciarticular juvenile chronic arthritis

Objectives - To determine whether polymorphisms of the TAP genes, which lie within the major histocompatibility complex (MHC), are associated with juvenile chronic arthritis (JCA). Methods - Eighty five JCA patients and 166 white controls were typed for the TAP gene alleles using ARMS-PCR. The same populations were analysed for DRB1 and DPB1 alleles using PCR-SSO typing. Results - TAP2B was increased in early onset pauciaricular JCA (EOPA-JCA) compared with controls (62% v 44% Odds ratio (OR) 2.1, 95% CI 0.9-4.7). After allowing for the known linkage disequilibrium between TAP2B and DR1 the association of TAP2B and EOPA-JCA was maintained (OR 3.5, 95% CI 1.3-9.7). HLA-DRB1*04 and TAP2D were found to be in linkage disequilibrium in both the control (Δ 0.018 p <0.05) and JCA patient groups (Δ 0.021 p <0.05). No linkage disequilibrium was found between the TAP and DPB1 alleles. Conclusions - The association between TAP2B and EOPA-JCA is a further indication of the heterogeneity which exists in this clinically defined subgroup of patients.