ADRB2 polymorphisms in allergic asthma in Han Chinese children

Single-nucleotide polymorphisms (SNPs) in the human β2 adrenergic receptor (ADRB2) gene have been linked to pathogenesis of and treatment responses in asthma. In China, where asthma is common, little information exists regarding ADRB2 variants and their effects on asthma. The current study sought to investigate the relationship between variations in ADRB2 and childhood asthma.

Blood samples were collected from 298 pediatric asthma cases treated in our hospital from July 2013 to September 2014; 304 samples were collected from healthy children for a control group. Six loci (at base positions -47, 79, -2387, 46, 523, and 491) of ADRB2 were genotyped using the TaqMan probe assay; SHEsis was used to determine haplotypes. Allele frequencies and genotype distributions were compared between groups using chi square and t tests.

No significant differences in genotype or allele frequencies were found between the groups for the polymorphic loci -2387 bp (T>C), 46 bp (G>A), and 523 bp (C>A) (p > 0.05). However, genotype frequencies for the ADRB2 SNPs at -47 bp (C>T) and 79 bp (G>C) differed significantly between asthma and control groups (p < 0.05). Further, linkage disequilibrium was found between these 2 SNPs (D' = 0.990, r(2) = 0.962), as well as between SNPs at 46 and 523 bp (D' = 0.985, r(2) = 0.607). Finally, of the 4 haplotypes analyzed in these samples (haplotypes III, IV, IX, and XI), the frequency of haplotype III was significantly lower in the asthma group than the control group (p < 0.05; odds ratio [OR] = 0.72; 95% confidence interval [CI], 0.48 to 0.97).

Variations of ADRB2 at base positions -47 (C>T) and 79 (G>C), as well as haplotype III, may contribute to susceptibility to childhood asthma.