Pharmacogenetic Tests in Asthma Therapy

β2-Agonist medications, such as albuterol and salmeterol, are widely used to treat asthma. However, there are a significant number of poor responders. Poor response may present as decreased lung function, and in extreme cases (a small percentage), patients who have asthma are at increased risk for mortality. A common single nucleotide polymorphism (SNP) in the β2-adrenergic receptor gene (ADRB2) results in an arginine substitution for glycine at amino acid 16 (Arg16→Gly) of the β2-adrenergic receptor protein. Although this SNP has been associated with increased responsiveness at therapy initiation, it has also been associated with decreased lung function and increased asthma exacerbations with long-term use of β2-agonists with or without corticosteroids in Caucasians. This pharmacogenetic relationship is less well studied in other ethnic groups. Experts have proposed that regular use of albuterol or salmeterol may be inappropriate for Caucasian asthmatics who have the homozygous ADRB2 Arg16 genotype.