HLA-C locus alleles in patients with psoriatic arthritis (PsA)

The aim of this investigation was to compare the frequency of alleles at th e HLA-C locus in patients with psoriatic arthritis to that in the disease f ree population and to relate the HLA genes to disease phenotype in psoriati c arthritis (PsA). Ninety-four consecutive patients seen in the (PsA) clini c between April and July 1996 and 100 disease-free controls had HLA typing performed by both serologic and molecular techniques. Patients' disease was assessed according to a standard protocol. Fisher's exact test was used to compare the frequency of HLA alleles in the patients and controls. HLA-C d etermined by PCR-SSP decreased the frequency of non-identified, that is, "b lank" (or null) alleles to 6% in patients and controls. HLA-Cw*0602 was pre sent in 32 patients and 18 controls: allele frequency of 17% in the patient s Versus 9% in the controls (p < 0.01). Amongst patients with psoriatic art hritis, those who carried the HLA-Cw*0602 allele had a significantly earlie r mean age of onset of their psoriasis (P = 0.003). This study confirms tha t molecular DNA techniques improve detection of C-locus alleles. The HLA-Cw *0602 is increased amongst patients with psoriatic arthritis compared to co ntrols. The HLA-Cw*0602 is associated with an earlier age of onset of psori wis. Human Immunology 60, 259-261 (1999). (C) American Society for Histocom patibility and Immunogenetics, 1999 Published by Elsevier Science Inc.