| The polymorphisms of angiotensin-converting enzyme2(ACE1) gene have been suggested to be linked to increase risk of essential hypertension in multiple populations. However, the results are still debatable. To assess the association between ACE2G8970A genetic polymorphism and essential hypertension, we conducted a meta-analysis of case-control studies across different ethnicity.PubMed, Embase, CBM, Wanfang and VIP databases were searched, and a total of11separate studies in females and9separate studies in males met the inclusion criteria. Because ACE2is on the X chromosome, data for each sex were analyzed separately. The selected studies contained7251(4472females/2779males) hypertensive patients and3800(2161females/1639males) normotensive controls.A statistically significant association was observed between the G8970A gene polymorphism and essential hypertension risk in female hypertensive group in the recessive genetic model (AA vs. GG+GA:P=0.03, OR=1.15,95%CI=1.02-1.30, Pheterogeneity=0.40,I2=5%, fixed-effects model). Although no association was shown between the frequency of the A allele and the genetic susceptibility to essential hypertension in all male patients (A Allele:P=0.38, OR=1.10,95%CI=0.89-1.38, heterogeneity=0.02, I2=56%, random-effects model), we found that the relationship between carrier of A allele and the essential hypertension risk in Han-Chinese male patients subgroup (A Allele:P=0.006, OR=1.21,95%CI=1.06-1.38,Pheterogeneity=0.10,I2=44%, fixed-effects model).The current meta-analysis provided solid evidence suggesting that ACE2gene polymorphism G8790A was probably a genetic risk factor for essential hypertension across different ethnic populations in female subjects and in Han-Chinese male subjects. Dopamine β-hydroxylase (DBH) catalyzes the conversion of dopamine to norepinephrine and is released from sympathetic neurons into the circulation. Recently, a novel polymorphism-1021C/T (rs1611115) in the5’flanking region of the DBH gene has been shown to account for up to52%of the variation in plasma DBH activity. Genetic deficiency of DBH manifests as hypotension in humans. We therefore investigated the possible association between the DBH-1021C/T polymorphism and orthostatic hypotension in a large Chinese community-based population.The DBH C-1021T polymorphism was genotyped in317patients with orthostatic hypotension and664age-and sex-matched controls with orthostatic normotensive subjects, all of whom underwent an upright posture study for orthostatic blood pressure measurements. Logistic regression analyses, adjusting for multiple confounders, were used to determine the association between the allele/genotype of DBHgene and the risk of orthostatic hypotension. Orthostatic hypotension was defined as a drop in blood pressure of20/10mmHg or more within3minutes of assuming the upright posture.The allele frequency of the DBH-1021C/T was similar in orthostatic hypotension patients and orthostatic normotensive subjects (17.4%vs.14.9%, p>0.05). No associations were found between the distribution of the-1021C/T genotypes and the risk of orthostatic hypotension in both orthostatic hypotensive patients and orthostatic normotensive subjects even after adjustment for demographic parameters and supine systolic or diastolic blood pressure. Among the three different genotypes, blood pressure levels did not significantly differ in general population in this study. The differences of orthostatic systolic or diastolic blood pressure changes among the different genotype groups were not detected (all p>0.05).In conclusion, we found no evidence that the C-1021G polymorphism in the5’ promoter region of the DBH was associated with a genetic predisposition to orthostatic hypotension risk in Chinese. |
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