Patients with nocturnal asthma were generally found to have >15% decrease in lung function during the night.[22] A number of single nucleotide polymorphisms in the β2-AR gene namely Arg/Gly at codon 16 and Gln/Glu at codon 27 have been implicated in asthma susceptibility.[10–12] A single amino acid substitution in the structural domains critical for receptor function has been shown to result in significant changes in receptor function.[7] However, these studies have generated conflicting results as to whether these genes alone confer a risk for asthma. Here, ADRB2 is linked to asthma.