IL13 genetic polymorphisms, smoking, and eczema in women: a case-control study in Japan

Background: Several genetic association studies have examined the relationships between single nucleotide polymorphisms (SNPs) in the IL13 gene and eczema, and have provided contradictory results. We investigated the relationship between the IL13 SNPs rs1800925 and rs20541 and the risk of eczema in Japanese young adult women. Methods: Included were 188 cases who met the criteria of the International Study of Asthma and Allergies in Childhood (ISAAC) for eczema. Control subjects were 1,082 women without eczema according to the ISAAC criteria, who had not been diagnosed with atopic eczema by a doctor and who had no current asthma as defined by the European Community Respiratory Health Survey criteria. Adjustment was made for age, region of residence, number of children, smoking, and education. Results: The minor TT genotype of SNP rs1800925 was significantly associated with an increased risk of eczema in the co-dominant model: the adjusted odds ratio was 2.19 (95% confidence interval: 1.03-4.67). SNP rs20541 was not related to eczema. None of the haplotypes were significantly associated with eczema. Compared with women with the CC or CT genotype of SNP rs1800925 who had never smoked, those with the TT genotype who had ever smoked had a 2.85-fold increased risk of eczema, though the adjusted odds ratio was not statistically significant, and neither multiplicative nor additive interaction was statistically significant. Conclusions: Our findings suggest that the IL13 SNP rs1800925 is significantly associated with eczema in Japanese young adult women. We could not find evidence for an interaction between SNP rs1800925 and smoking with regard to eczema.