关键词: 特应性皮炎, IL-18, PCR-SSP

Abstract: Objective To investigate the polymorphism at positions -137 and -607 in the upstream promoter 1 region of exon 2 of interleukin （IL）-18 gene in Han children with atopic dermatitis （AD） in Chongqing, China, as well as its correlation with the development of AD. Methods Blood samples were collected from 82 patients with atopic dermatitis and 100 healthy controls. DNA was extracted from the samples and subjected to test with PCR. The polymorphism of IL-18 gene at positions -137 and -607 in the upstream promoter 1 region was analyzed by polymerase chain reaction （PCR）- sequence specific primers （SSP） and gene sequencing．Genotype frequency was compared between the patients and controls. Results A G/C polymorphism （GG, GC and CC genotypes） was identified at position -137 in exon 2 of IL-18 gene, and a C/A polymorphism （CC, CA and AA genotypes） at position -607 of this gene. The frequency of genotype GC at position -137 was significantly higher in the patients than that in the controls （47% vs 27%, P < 0.05; odds ratio = 2.33, 95% confidence interval 1.26 - 4.33）. Increased frequency of C allele was also noted at the position -137 in the patients compared with the controls （0.24 vs 0.15, P < 0.05; odds ratio = 1.76, 95% confidence interval 1.04 - 2.97）. Patients with severe AD （SCORAD score > 50） were more likely to carry C allele at position -137 of IL-18 gene than those with mild AD （SCORAD < 20）. There was no statistical difference in allele frequency at -607 （C/A） among patients with mild, moderate, severe AD and the controls （P > 0.05）. Conclusions There is a polymorphism at positions -137 and -607 in the upstream promoter 1 region of IL-18 exon 2. The GC genotype of IL-18 at position -137 may confer the susceptibility to AD in Han children in Chongqing.