Abstract: Objective To study the responsible genes of psoriasis vulgaris on chromosome 1q21 in Chinese Han population. Methods Thirty-six families with psoriasis vulgaris, including 92 patients and 98 normal relatives, aged from 12 to 81 years with an average age at 44 years, were enrolled in this study. Blood samples were obtained from all the participants and subjected to DNA extraction. A genome scan was performed with eight microsatellites distributing over chromosome 1q21-1q23.1. Evidence for linkage disequilibrium was assessed with extended transmission disequilibrium test （ETDT） program and GENEHUNTER software. Results Three short tandem repeat markers were found to be associated with psoriasis vulgaris. With GENEHUNTER, evidence for linkage disequilibrium between D1S2345 and psoriasis was found with the NPL value being 1.735 （P = 0.0329）. Moreover, ETDT revealed that the 97-bp allele of D1S2346 and 283-bp allele of D1S484 were preferentially delivered to affected descendants （P < 0.05）. Conclusion Chromosome 1q21 contains genes associated with psoriasis vulgaris in Chinese Han population.

Key words: Psoriasis, Chromosome 1, Linkage, Microsatellite