In vitro studies have shown that the nonsynonymous single-nucleotide polymorphism at position 46 of the ADRB2 gene (ADRB2 Gly16Arg) significantly enhances the receptor downregulation effect mediated by agonists and may influence the therapeutic efficacy of inhaled corticosteroids, making it an important potential biomarker for personalized asthma treatment [58,59]. This evidence concerns the gene ADRB2 and asthma.