Human leukocyte antigen alleles and susceptibility to psoriatic arthritis.

OBJECTIVE

Our purpose was to determine associations between HLA alleles and psoriatic arthritis (PsA).

METHODS

678 PsA cases and 688 healthy controls were analyzed in a case-control design. The difference in the proportion of cases and controls with at least 1 copy of HLA alleles were tested for significance using χ(2) test and Fisher's exact test. Association analyses of haplotypes inferred by the Expectation-Maximization algorithm were performed. In the family-based association study, data from 283 families were analyzed.

RESULTS

Univariate analysis revealed that cases were more likely to be carriers of HLA-C01, -C02, -C06, -C12, -B27, -B38 and -B57, whereas controls were more likely to be carriers of HLA-C03, -C07, -B07, -B51, -DRB115 and -DQB10602. In haplotype analyses, PsA cases were more likely to be carriers of the HLA haplotypes -C01/-B27, -C02/-B27, -C12/-B38, and -C06/-B57, while controls were more likely to be carriers of the haplotypes -C07/-B07 and -C15/-B51. In the family-based association analysis, the HLA alleles -A02, -B27 and -DRB107 were preferentially transmitted to cases, whereas the alleles -A03, -A28, -B51, -DRB111 and -DQB1*0301 were under transmitted.

CONCLUSION

This large case-control and family based association study shows that HLA-C12/B38, HLA-B27 and HLA-C06/B*57 are haplotypes (alleles) robustly associated with PsA. However, since patients with PsA also have psoriasis it is difficult to determine whether the primary association is with arthritis or psoriasis.