Single nucleotide polymorphisms and the haplotype in the DEFB1 gene are associated with atopic dermatitis in a Korean population

Abstract

Atopic dermatitis (AD) patients have been recognized to have an increased susceptibility to cutaneous colonization and infection by bacteria, fungi and viruses. We wanted to evaluate the associations of single nucleotide polymorphism (SNP) and the haplotype in the defensin (DEFA) and defensin (DEFB) genes, and so we performed genotyping for the SNPs in these genes in both AD patients and normal controls. We genotyped 27 SNPs from the DEFA 4, 5 and 6 genes and the DEFB1 gene for 1089 case-control samples (631 AD patients and 458 normal controls). We analyzed the SNPs and haplotypes in each gene. We identified that two SNPs and the haplotype CT in the DEFB1 gene are associated with AD in Koreans. The rs5743399 (-2266T/C) SNP is associated with AD, and especially with the high IgE, extrinsic type, and the rs5743409 (-1241T/G) SNP is associated with AD. On the haplotype analysis of these two SNPs, the haplotype CT is associated with AD, and especially with the allergic, extrinsic type of AD. However, we could not find any significant associations between the SNPs in the three DEFA genes and AD. We found that the rs5743399 SNP, the rs5743409 SNP and the CT haplotype in the DEFB1 gene were significantly associated with the susceptibility to AD. We also found that rs5743399 polymorphism and the haplotype CT in this gene showed a strong association with the allergic, extrinsic type of AD. These results suggest that the DEFB1 gene has a main effect on the skin inflammation and/or skin responsiveness to any kind of allergic reaction.