β₂-receptor polymorphism 'protects against coronary events'

The authors analysed more than 5000 men and women participating in the Cardiovascular Health Study (CHS), a large observational cohort study of risk factors for cardiovascular disease (CVD) in the elderly. For the present study, participants with a history of CVD were excluded, leaving 4441 white and 808 black individuals. The researchers examined the association between incident CVD and ⓶-adrenergic receptor genotype within the CHS cohort by genotyping for theArg16Gly and Gln27Glu, polymorphisms of the ⓶-adrenergic receptor. They reported 702 incident coronary events (defined as myocardial infarction, MI, or cardiac death), 438 ischemic strokes, and 1136 combined CV events defined as first occurrence of angina, MI, transient ischemic attack, ischemic stroke, peripheral vascular disease, or death attributable to atherosclerotic disease) during 7-10 years of follow-up. Heckbert et al found that carriers of the Glu27 allele had a lower risk of coronary events than Gln27 homozygotes (hazard ratio: 0.82; 95% confidence interval [CI] 0.70-0.95). This association was particularly evident in people who were free of CVD or had untreated hypertension. They also found a suggestion of a decreased risk among Gly16 carriers compared with Arg16 homozygotes (hazard ratio: 0.88; 95% CI: 0.72-1.07). "We know that variations in the gene for the ⓶-adrenergic receptor can change how the receptors respond to activation by adrenaline and related compounds, but there has been little information about how it relates to the risk of heart disease" said the authors. They conclude that the results of the study suggest that the effects of adrenergic stimulation may be modified by genetic variation, thereby affecting the risk of coronary events. Heckbert et al call for further studies to clarify whether the differences in CVD risk are due to the alterations in vascular response associated with this polymorphism, and to evaluate the use of genetic testing in CVD risk stratification....