Table 3.

Polymorphisms of β-AR subtypes that influence responsiveness or receptor regulation in response to activation by directly or indirectly acting agonists

Mutation	Substitution	Functional changes	Allele frequency by race/ethnicity
			Caucasian	Afro-American	Asian	Hispanic
β1-AR polymorphisms
145 A>G	Ser49Gly	Gly49 variant shows constitutive activity and enhanced downregulation	0.12–0.16	0.13–0.15 0.23–0.28	0.15	0.20–0.21
1165 C>G	Gly389Arg	Gly389 variant is ‘hypofunctional'	0.24–0.34	0.39–0.46	0.2–0.3	0.31–0.33
β2-AR polymorphisms
46 A>G	Arg16Gly	Gly16 variant more susceptible to downregulation	0.38–0.46	0.49–0.51	0.54–0.59	NA
79 C>G	Gln27Glu	Glu27 variant resistant to downregulation	0.35–0.46	0.20–0.27	0.07–0.20	NA
491 C>T	Thr164Ile	Ile164 variant shows reduced binding, signalling and internalization	0.02–0.04	0.02–0.04	0–0.01	0.03
β3-AR polymorphisms
190 T>C	Trp64Arg3	Arg64 variant shows reduced cAMP in response to stimulation	0.08	0.10	0.184	0.16

Abbreviations: β-AR, β-adrenoceptor; NA, not applicable.

Only the more commonly found polymorphisms or those displaying a clear phenotype are shown. For detailed information, see Kirstein and Insel (2004) and Brodde (2008).

³American Pima Indians have an incidence of 0.31 and also have a high incidence of obesity and type II diabetes.

⁴Japanese Americans.