Methods: We genotyped 763 children for allelic determinants at four polymorphic sites, which were -465T>C, -413C>T, 314C>T and 939A>G in the HNMT gene, and the functional effect of the 939A>G polymorphism was analyzed. The genotyping was screened using the TaqMan fluorogenic 5’ nuclease assay (ABI, Foster City, CA, USA).
Results: Among these 763 children, 520 had eczema and 542 had atopy. Distributions of the genotype and allele frequencies of HNMT 314C>T polymorphism were significantly associated with non-atopic eczema (P = .004) and those of HNMT 939A>G polymorphism were significantly associated with eczema in atopy groups (P = .048). However, those of HNMT 654T>C and 413C>T polymorphisms were not. In addition, subjects with the homozygous AA or heterozygous AG of the 939A>G polymorphism showed significantly higher IgE levels than those with the homozygous GG genotype (P = .009). In U937 cells, the variant genotype reporter construct showed significantly higher mRNA stability (P < .001) and HNMT enzyme activity (P < .001) than the common genotype.
Conclusions: Polymorphisms in the HNMT gene appear to confer susceptibility to atopic dermatitis in Korean children.