Four-locus gene interaction between IL13, IL4, FCER1B, and ADRB2 for asthma in Chinese Han children.

RATIONALE: IL13, IL4, IL4RA, FCER1B, and ADRB2 are important inflammatory genes associated with immunoglobulin E levels. This study attempts to determine whether there are gene-gene interactions in the five genes among asthmatic children of Chinese Han nationality. METHODS: Nine single-nucleotide polymorphisms (SNPs) in the five genes were genotyped in 1,000 asthmatic children and 1,000 healthy controls using TaqMan real-time quantitative polymerase chain reaction. Multifactor-dimensionality reduction method was applied for the analysis. RESULTS: A four-way gene-gene interaction model consisting of IL13 rs20541, IL4 rs2243250, ADRB2 rs1042713, and FCER1B rs569108 was chosen as the optimal one for determining asthma susceptibility (testing balanced accuracy = 0.6089, cross-validation consistency = 10/10, P = 6.98E-05). Each of the four SNPs was identified to have an independent association with childhood asthma (G allele of rs20541, odds ratio (OR) = 1.24, P = 1.23E-03; T allele of rs2243250, OR = 1.25, P = 3.81E-03; A allele of rs1042713, OR = 1.29, P = 6.75E-05; G allele of rs569108, OR = 1.27, P = 3.86E-03). Individuals homozygous for the risk alleles at all the four loci (rs20541 GG, rs2243250 TT, rs1042713 AA, and rs569108 GG) had a significantly higher risk of asthma compared with those without any risk homozygotes (OR = 13.55, P = 4.28E-03), and also greater than those with less than four risk homozygotes (OR = 10.09, P = 6.51E-03). CONCLUSIONS: Our results suggest that IL13 rs20541, IL4 rs2243250, ADRB2 rs1042713, and FCER1B rs569108, four SNPs with significant sole effect on asthma, interact to confer a higher risk for the disease in Chinese Han children.