1. ¹Department of Physiology, University of Tartu, Tartu, Estonia
2. ²Department of Dermatology and Venerology, University of Tartu, Tartu, Estonia
3. ³Centre of Molecular and Clinical Medicine, University of Tartu, Tartu, Estonia

Correspondence: Dr S Kõks, Department of Physiology, University of Tartu, 19 Ravila Street, 50411 Tartu, Estonia. E-mail: Sulev.Koks@ut.ee

Received 22 June 2004; Revised 27 August 2004; Accepted 27 August 2004; Published online 21 October 2004.

Abstract

There is increasing evidence to suggest that the newly discovered cytokines interleukin (IL)-19 and -20 have a role in the function of epidermis and in psoriasis. The genes encoding these cytokines locate into the genomic IL-10 region on human chromosome 1. The aim of the present study was to analyze whether single-nucleotide polymorphisms (SNPs) in these genes have an impact on the susceptibility for psoriasis. From pairwise linkage disequilibrium (LD) matrix of the IL-19 and -20 gene polymorphisms, what reflects the nonrandom association of alleles at these markers, it was apparent that IL-19 and -20 genes form one block of LD. We found that the HT3 CACCGGAA haplotype of the IL-19 and -20 genes was associated with an increased risk of psoriasis, reflecting its role in determining susceptibility to plaque-type psoriasis. Although association analysis of the IL-19 gene indicated that minor alleles of the IL-19 gene SNPs (rs2243188, rs2243169 and rs2243158) revealed protective effect to psoriasis and haplotype analysis of the IL-19 gene proved significant protective effect of the TGATA haplotype in case of late-onset disease, combined haplotype analysis of the IL-19 and -20 genes demonstrated that protective effect of the IL-19 gene is secondary to the susceptibility effect of the IL-20 gene.