β2-adrenergic receptor gene and resting hemodynamics in European and African American youth

Background: The β2-adrenergic receptor (ADRB2) contributes to blood pressure (BP) regulation by mediating peripheral vasodilation. Associations between the Arg16Gly and Gln27Glu polymorphisms of the ADRB2 gene and BP among multiethnic adult samples have been mixed. The purpose of this study was to investigate the relationship between these polymorphisms and resting hemodynamic function in African American (AA) and European American (EA) youths. Methods: We studied 395 EA and 275 AA twins from the southeastern United States (mean age, 14.6 ± 3.0 years; range, 10.0 to 25.9 years). The Arg16Gly and Gln27Glu polymorphisms were detected by polymerase chain reaction, followed by restriction enzyme digestion, and confirmed by direct sequence analysis. The effect of the polymorphisms on resting hemodynamics was analyzed using structural equation modeling. Results: For the Arg16Gly polymorphism, carriers of one or two Gly alleles exhibited significantly higher levels of systolic BP and pulse pressure in EA, respectively, explaining 2.6% and 2.8% of the variance. No significant associations were seen in AA. Carriers of the Glu allele of the Gln27Glu polymorphism showed an elevated systolic and diastolic BP, mean arterial pressure, total peripheral resistance index, and a lower stroke volume in EA. In AA, only diastolic BP showed a higher level in Glu carriers. Between 1.3% and 4.1% of the variance in these hemodynamic measures was explained by the Gln27Glu locus. Conclusions: The findings suggest that vasodilatory related genetic factors play a particularly important role in BP control in EA youths.