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 patient s and 166 white controls were typed for the TAP gene alleles using ARM S-PCR. The same populations were analysed for DRB1 and DPB1 alleles us ing PCR-SSO typing. Results-TAP2B was increased in early onset pauciar ticular JCA (EOPA-JCA) compared with controls (62% v 44% Odds ratio (O R) 2.1, 95% CI 0.9-4.7). After allowing for the known linkage disequil ibrium between TAP2B and DR1 the association of TAP2B and EOPA-JCA was maintained (OR 3.5, 95% CI 1.3-9.7). HLA-DRB104 and TAP2D were found to be in linkage disequilibrium in both the control (Delta 0.018 p < 0.05) and JCA patient groups (Delta 0.021 p < 0.05). No linkage disequ ilibrium was found between the TAP and DPB1 alleles. Conclusions-The a ssociation between TAP2B and EOPA-JCA is a further indication of the h eterogeneity which exists in this clinically defined subgroup of patie nts