The frequency of α₂-adrenoceptor restriction fragment length polymorphisms in normotensive and hypertensive humans

Objective: To examine the frequency of distribution of allelic polymorphisms of the α₂-adrenoceptor gene in normotensive and hypertensive humans. Design: The frequency of α₂-adrenoceptor genotypes was compared in the two groups using the χ^2-test. Setting: The Midwest Hypertension Research Center Outpatient Clinic of Creighton University School of Medicine. Study participants: History was taken from and physical examination performed on each of the 60 hypertensive and 47 normotensive adults. Methods: DNA was extracted from leukocytes from each participant. Twenty restriction endonucleases were used and one restriction fragment length polymorphism (RFLP) was found using a 950-bp restriction fragment from the coding region of the human platelet α₂-adrenoceptor gene (ADRA2R) and Bsu361 restriction endonuclease. This probe and Bsu361 restriction endonuclease, in addition to another restriction endonuclease (Dra I), were then used in the study. Results: Three genotype patterns were found. Homozygotes for the Bsu361 RFLP have either a unique 12-kb or a unique 5.8-kb band. Heterozygotes have both bands. The frequency of this α₂-adrenoceptor RFLP was calculated. In hypertensives the frequencies of the 12- and 5.8-kb alíeles were 0.52 and 0.48, compared with 0.45 and 0.55, respectively, in normotensive, a difference that was not statistically significant. Conclusions: The frequency of the Bsu36l RFLP involving an α₂-adrenoceptor gene in hypertensives did not differ significantly from that in normotensives. A genetic linkage study is now under way to test for an association of the Bsu36l RFLP of the α₂-adrenoceptor gene with essential hypertension in families.