Correlation of gene polymorphism of interleukin 4 receptor alpha peptide chain and total serum IgE levels in asthmatic children in Guiyang area

Abstract

To explore the correlation of gene polymorphism of interleukin 4 receptor alpha chain (IL-4Rα) and total serum IgE levels in children of bronchial asthma in Guiyang area. A total of 160 asthmatic children at Affiliated Hospital, Guiyang Medical College from August 2010 to February 2011 were selected as asthma group. There were 96 males and 64 females with an average age of (6.9 ± 3.3) years. During the same period, 143 healthy children from outpatient physical examination center of this hospital were chosen as control group. There were 75 males and 68 females with an average age of (4.9 ± 3.9) years. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and allele-specific polymerase chain reaction (AS-PCR) were used to determine the polymorphisms of Q576R on exon 12 and I75V on exon 5 of IL-4Rα in both groups. The total serum IgE levels were determined by enzyme-linked immune sorbent assay (ELISA). Comparisons of two groups were made for genotype and allele frequency, serum total IgE and different genotypes, different groups of total serum IgE levels. Three genotypes of AA, AG and GG existed on Q576R and I75V loci between two groups. The genotypic frequencies of two loci had significant differences in two groups (χ(2) = 30.972, 16.776, both P < 0.001). The subjects with variant allele on Q576R and I75V loci had higher risks for asthma than those without variant allele (χ(2) = 33.236, 13.845, both P < 0.001). The total serum levels of IgE in asthma group were higher than those in control group ((312 ± 297) vs (61 ± 48) U/ml, t = 9.959, P < 0.001). However, these three genotypes of two loci showed no significant inter-group difference (all P > 0.05). In mutation allele carriers and non-carriers of Q576R locus, total IgE levels showed no significant difference (t = -0.028, 1.279; P = 0.978, 0.203). Differences in total IgE levels between I75V polymorphic variant allele carriers and non-carriers were also not statistically significant in control group (t = -0.763, P = 0.447). However, in asthma group, total IgE levels of I75V polymorphic variant allele carriers were significantly higher than those of non-carriers (t = -2.112, P = 0.036). The 576 and 75 loci of IL-4Rα are important candidate genes of asthmatic children in Guiyang area. And the serum total IgE levels of variant allele G at 75 locus in IL-4Rα are higher than those without it.