The Association between the IL-20-1723C→G Allele on the 1q Chromosome and Psoriasis Triggered or Exacerbated by an Upper Respiratory Tract Infection in the Chinese Han Population

Background: Psoriasis is a cutaneous disorder of multifactorial etiology influenced by both genetic and environmental factors such as infection. Methods: We conducted a genome analysis with 20 microsatellite markers spanning the long arm of chromosome 1 in 36 Chinese families with psoriasis and detected evidence for linkage at 1q21 with a nonparametric linkage score of 1.74, p = 0.03, and 1q32 with one of 1.84, p = 0.03. According to the positional and functional candidate principle, we further investigated the single-nucleotide polymorphisms of the HAX-1 gene (located in 1q21) and IL-20 gene (located in 1q32) in a case-control study including 340 sporadic patients and 199 controls. Results: We determined that the frequency of the G allele of IL-20 -1723C -> G (rs1713239) was significantly higher among psoriatic patients (38.5% in cases vs. 31.2% in controls, p = 0.015, odds ratio, OR = 1.39, 95% confidence interval, Cl = 1.07-1.80). When we stratified our analysis by psoriasis triggered or exacerbated by infection of the upper respiratory tract, a significant difference was detected (42.4% in stratified cases vs. 31.2% in controls, p = 0.005, OR = 1.63,95% CI = 1.15-2.30). Conclusion: We assume that triggered or exacerbated by respiratory tract infection, the population with the G allele of IL-20 -1723C -> G are predisposed to psoriasis. Copyright (C) 2010 S. Karger AG, Basel