The frequency of alpha 2-adrenoceptor restriction fragment length polymorphisms in normotensive and hypertensive humans.

Objective: To examine the frequency of distribution of allelic polymorphisms of the alpha 2-adrenoceptor gene in normotensive and hypertensive humans.
Design: The frequency of alpha 2-adrenoceptor genotypes was compared in the two groups using the chi 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 participants. 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 alpha 2-adrenoceptor gene (ADRA2R) and Bsu36I restriction endonuclease. This probe and Bsu36I 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 Bsu36I RFLP have either a unique 12-kb or a unique 5.8-kb band. Heterozygotes have both bands. The frequency of this alpha 2-adrenoceptor RFLP was calculated. In hypertensives the frequencies of the 12- and 5.8-kb alleles 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 Bsu36I RFLP involving an alpha 2-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 Bsu36I RFLP of the alpha 2-adrenoceptor gene with essential hypertension in families.