Genetic Polymorphisms of the -Adrenoreceptors

Beta-1, beta-2, and beta-3 adrenergic receptors are G-protein-coupled receptors. Beta-1 and beta-2 receptors mediate the positive inotropic, chronotropic, and dro-motropic effects of the endogenous catecholamines epinephrine and norepinephrine. The beta-3 subtype seems to play a role in regulating thermogenesis and lipid mobilization in brown and white adipose tissue. Several coding and promoter polymorphisms of these receptors have been identified. Clinical studies in asthma 

Polymorphisms of the beta adrenergic receptors have also been studied in patients with heart failure and cardiomyopathy, or other complex and rather ill-defined phenotypes. In patients with heart failure due to ischemic or idiopathic dilated cardiomyopathy, the Thrl64Ile polymorphism in the / 2-adrerioreceplor was significantly associated with survival rate at one year [62]. Similarly, the Ser49Gly polymorphism of the /Vadrenoreceptor gene has been linked to the improved survival of patients with idiopathic cardiomyopathy [63]. However, sample size was limited in those studies and results need to be confirmed in adequately powered studies. 

It is intriguing to note that the 13 SNPs reported for the / 2-adrenoreceptor gene could theoretically lead to 213 different combinations. However only 12 haplotypes were observed [57]. To date, no such a study has been reported for the / radreno-receptor gene, in which 18 polymorphisms giving rise to only 11 haplotypes are known [70]. 

1 Hanash SM. Operomics Molecular analysis of tissues from DNA to RNA to protein. Clin Chem Lab Med 2000 38 805-813. 

2 Nebert DW. Pharmacogenetics and phar-macogenomics why is this relevant to the clinical geneticist Clin Genet 1999 56 247-258. 

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