At a nominal significance level, we replicated gene-level associations for all of the candidate genes other than ADRB2. This gene, which encodes the β2AR, is the most studied gene related to BDR and SNPs and haplotypes in this gene have been related to decreased pulmonary function [29], response to β2-agonist treatment [30], an increased frequency of asthma exacerbations [31], and BDR [13], [14]. This evidence concerns the gene ADRB2 and asthma.