Abstract: Objective To explore the association of codons at position 73 of HLA-C with psoriasis vulgaris (PV) for the Hans in Hubei province. Methods Polymerase chain reaction (PCR)—denatured polyacrylamide gel electrophoresis—DNA silver stain technique and DNA sequencing of PCR products were employed to detect the codons at position 73 of HLA-C in 104 patients with psoriasis vulgaris and 110 healthy controls. Results① The frequencies of nucleotide sequence codin g alanine at position 73 of HLA-C antigens (⁷³Ala) were significantly higher in patients (81.7%) than those in controls (53.6%)[relative risk (RR)=3.87, χ²=19.12, P<0.005)]. However, the frequencies of nucleotide sequencecoding threonine at position 73 of HLA-C antigens (⁷³Thr) were significantly lower in patients (77.9%) than those in controls (89.1%), (RR=0.43,χ²=4.92, P<0.05).② The frequencies of ⁷³Ala was significantly higher in patients with a familial history (100%) of psoriasis than those in cases without familia l history (77.6%), (χ²=5.39, P<0.025). However, contrary results were obtained with the frequencies of 73Thr (57.9% versus 82.4%,χ²=5.40, P<0.025). Conclusions ⁷³Ala of HLA-C gene may play a role in the susceptibi lity to PV, but ⁷³Thr of HLA-C gene seems to be a protective factor to PV in the Hans.

Key words: Psoriasis, HLA-C antigens, Base sequence