Asthma treatment with albuterol, which is targeted to ADRB2, is often associated with increased hypersensitivity (Reihsaus et al., 1993; Dewar et al., 1997; Liggett, 1997; Drysdale et al., 2000; Israel et al., 2000; Littlejohn et al., 2002). This evidence concerns the gene ADRB2 and asthma.