Similarity of blood pressure for each genotype of the insertion/deletion polymorphism of the dipeptidyl carboxypeptidase-1 gene in different age groups of patients with severe, familial essential hypertension

Hypertension: genes and environment

Hypertension can be classified as either Mendelian hypertension or essential hypertension, on the basis of the mode of inheritance. The Mendelian forms of hypertension develop as a result of a single gene defect, and as such are inherited in a simple Mendelian manner. In contrast, essential hypertension occurs as a consequence of a complex interplay of a number of genetic alterations and environmental factors, and therefore does not follow a clear pattern of inheritance, but exhibits familial aggregation of cases. In this review, we discuss recent advances in understanding the pathogenesis of both types of hypertension. We review the causal gene defects identified in several monogenic forms of hypertension, and we discuss their possible relevance to the development of essential hypertension. We describe the current approaches to identifying the genetic determinants of human essential hypertension and rat genetic models of hypertension, and summarise the results obtained to date using these methods. Finally, we discuss the significance of environmental factors, such as stress and diet, in the pathogenesis of hypertension, and we describe their interactions with specific hypertension susceptibility genes.

Association of angiotensin II type 1 receptor gene polymorphism with essential hypertension

The renin-angiotensin system is involved in control of blood pressure and salt and fluid homeostasis. Genes for components of this system have been of major focus in research on the causation of the common, complex, polygenic trait, essential hypertension (HT). Association of an A-->C variant at nucleotide 1166 of the angiotensin II type 1 receptor (AT1R) gene with HT, but an absence of linkage of this locus with this disease, has been reported recently. Since confirmation in a different setting is imperative, we performed a cross-sectional case-control study of the A1166C variant in a well-characterized group of 108 Caucasian HT subjects with a strong family history (two affected parents) and early onset disease. Genotyping was by mismatch polymerase chain reaction/BfrI restriction fragment length polymorphism analysis. Frequency of the C1166 allele was 0.40 in HTs and 0.29 in normotensives. The difference in genotype (chi 2 = 13, P = 0.0015) and allele (chi 2 = 5.3, P = 0.02) frequencies between the two groups was significant (odds ratio for CC vs AA + AC = 7.3 [95% CI, 1.9-31.9). The present results implicate the AT1R gene, or a locus in linkage disequilibrium with the variant tested, in the causation of essential HT.

Effect of angiotensin-converting enzyme genotype on renin-angiotensin components in hypertensives

Plasma angiotensin-converting enzyme (ACE) tracks with the deletion allele of an insertion/deletion (I/D) polymorphism of the ACE gene. The aim of the present study was to determine plasma renin and angiotensinogen for each ACE genotype in 54 hypertensive and 96 normotensive subjects. Plasma renin was reduced by 52 +/- 15 S.E.% in DD and by 24 +/- 12% in ID hypertensives when compared to II hypertensives (P < 0.05 by one-way ANOVA), but in the normotensive subjects, renin values were similar for each genotype. Plasma angiotensinogen did not differ across ACE genotypes, but was elevated by 25 +/- 3 S.E.% in hypertensives and showed a significant correlation with blood pressure. In conclusion, although renin does not differ significantly between ACE genotypes of normotensives, a reciprocal relationship may exist between plasma renin and plasma ACE in hypertensives.