Objective: To examine and compare angiotensin II type 1 receptor genotype and its relationship to platelet angiotensin II binding for pre-eclamptic and normotensive pregnant women.
Design: In a case-control study, 43 pre-eclamptic women and 83 normotensive women were genotyped at the angiotensin II type 1 receptor gene locus. Platelet angiotensin II binding was measured for a subset of 11 pre-eclamptic and 57 normotensive pregnant women. We genotyped 162 healthy blood donors also, to examine the allelic background and patterns of linkage disequilibrium in the Nottingham population.
Methods: Patients were recruited during pregnancy using a rigorous definition of pre-eclampsia. DNA was extracted from peripheral venous blood and genotyped at six previously described diallelic polymorphisms in the angiotensin II type 1 receptor gene, using competitive allele-specific oligonucleotide hybridization, and at a dinucleotide repeat polymorphism in the 3' flanking region of the gene. Platelet angiotensin II binding and plasma angiotensin II concentrations were determined for peripheral venous blood.
Results: Normotensive pregnant women homozygous for cytosine at nucleotide 573 had significantly higher levels of platelet angiotensin II binding than did heterozygous women and women homozygous for thymidine at this site. Pre-eclamptic women had significantly higher levels of platelet angiotensin II binding than did normotensive pregnant women. The frequencies of allelic variants did not differ significantly between normotensive and pre-eclamptic women.
Conclusion: The physiological regulation of platelet angiotensin II type 1 receptor expression in normal pregnancy is determined in part by angiotensin II type 1 receptor genotype. There was no evidence that the polymorphisms in the angiotensin II type 1 receptor gene were associated with pre-eclampsia.