GENETIC-ANALYSIS OF TAP2 IN SYSTEMIC LUPUS-ERYTHEMATOSUS PATIENTS FROM 2 ETHNIC-GROUPS

The aim of this study was to determine whether the TAP2 (Transporter a ssociated with Antigen Processing 2) locus is involved in susceptibili ty to systemic lupus erythematosus (SLE). We adopted the interethnic a pproach to overcome problems in the analysis resulting from linkage di sequilibrium. The TAP2 gene polymorphisms of the codons corresponding to amino acid positions 379, 565 and 665 were investigated by amplific ation refractory mutation system polymerase chain reaction (ARMS-PCR) in 186 patients (151 white Europeans, 35 Afrocaribbeans) and 183 contr ols (79 white Europeans, 104 Afrocaribbeans). In the European SLE pati ents, the frequency of the TAP2 type V-A-TA was marginally lower compa red with the control group (31% vs 42%), with negative linkage disequi librium between this TAP2 type and DR3 probably accounting for the dif ference. For the European SLE patients, we confirmed a significant ass ociation of DR3 with disease status [odds ratio = 4.16, 95% confidence interval (CI), 2.08-8.39] and in the patients with DR3 there was a si gnificantly high frequency of the TAP2 type V-A-T-. In the Afrocaribbe an SLE patients, any associations of disease status with TAP2 phenotyp e were the inverse of those in the European patients. Thus, in these p atients the frequency of V-A-TA was higher than in controls (46% vs 26 %, OR = 2.4, 95% CI 1.01-5.74), while the frequency of V-A-T- was lowe r (26% vs 40%, not significant). Despite possible sampling error, the lack of a difference in TAP2 status between cases and controls within ethnic groups and, if anything, an inverse association across ethnic g roups, makes it unlikely that the TAP2 polymorphism studied here is of primary relevance to SLE susceptibility.