HLA-C locus alleles distribution in patients from northern Poland with psoriatic arthritis--preliminary report.

The aim of the study was to compare the frequency of human leucocyte antigen-C (HLA-C) locus alleles in patients with psoriatic arthritis and in healthy controls in the same ethnic group in Poland, and to correlate them with age of onset of psoriatic skin changes and joints symptoms. HLA-C locus alleles of 41 patients and 80 controls were determined by a polymerase chain reaction (PCR) low-resolution method. The Cw*06 allele occurred more frequently (P adjusted for multiple comparison = 0.004) in patients with psoriatic arthritis than in controls. Patients who carried the HLA-Cw*06 allele had a significantly earlier mean age of onset of both psoriasis (P = 0.01) and arthritis (P = 0.008) compared with Cw*06-negative patients. Our results confirm the association between Cw*06 allele and psoriatic arthritis in the northern Poland population and suggest that the HLA-Cw*06 may determine not only the disease susceptibility, but also the age of onset of psoriatic arthritis.