Reassignment of human renin gene to chromosome 1q32 in studies of a (1;4)(q42;p16) translocation

Molecular genetics of essential hypertension

Hypertension is a major public health problem in the developing as well as in developed countries due to its high prevalence and its association with coronary heart disease, renal disease, stroke, peripheral vascular disease, and related disorders. Essential hypertension (EH) is the most common diagnosis in this disease, suggesting that a monocausal etiology has not been identified. However, a number of risk factors associated with EH have also been identified such as age, sex, demographic, environmental, genetic, and vascular factors. Recent advances in molecular biological research had achieved clarifying the molecular basis of Mendelian hypertensive disorders. Molecular genetic studies have now identified mutations in several genes that cause Mendelian forms of hypertension in humans. However, none of the single genetic variants has emerged from linkage or association analyses as consistently related to the blood pressure level in every sample and in all populations. Besides, a number of polymorphisms in candidate genes have been associated with differences in blood pressure. The most prominent candidate has been the polymorphisms in the renin-angiotensin-aldosterone system. In total, EH is likely to be a polygenic disorder that results from inheritance of a number of susceptibility genes and involves multiple environmental determinants. These determinants complicate the study of blood pressure variations in the general population. The complex nature of the hypertension phenotype makes large-scale studies indispensable, when screening of familial and genetic factors was intended. In this review, recent genetic studies exploring the molecular basis of EH, including different molecular pathways, are highlighted.

The C4280A (rs5705) gene polymorphism of the renin (REN) gene is associated with risk of developing coronary artery disease, but not with restenosis after coronary stenting

The aim of the present study was to evaluate the role of AGT and REN gene polymorphisms as susceptibility markers for coronary artery disease (CAD) and/or restenosis after coronary stent placement in a group of Mexican patients. Five polymorphisms of the AGT (rs699, rs4762, rs5051, rs5049, rs5046) and two of the REN (rs5707, rs5705) genes were analyzed by 5' exonuclease TaqMan genotyping assays in 240 patients with CAD who underwent coronary artery stenting (76 with restenosis and 164 without restenosis). A group of 610 individuals without clinical and familial antecedents of cardiovascular diseases were included as controls. The results showed that the distribution of AGT and REN polymorphisms were similar in patients with and without restenosis. However, when the whole group of patients (with and without restenosis) was compared to healthy controls, under co-dominant, dominant, heterozygous and additive models, the REN A4280C (rs5705) polymorphism was associated with increased risk of CAD (OR=1.76, PCo-dom=0.006, OR=1.81, PDom=0.001, OR=1.75, PHet=0.003 and OR=1.59, PAdd=0.003, respectively). All models were adjusted for age, gender, diabetes, dyslipidemia, hypertension and smoking habit. The TC haplotype of the REN gene was associated with increased risk of CAD (OR=1.53, P=0.014). The data suggest that the REN C4280A (rs5705) polymorphism plays an important role in the risk of developing CAD with the highest risk for C allele, but do not support its role as a risk factor for developing restenosis after coronary stenting.

Renin: from 'pro' to promoter

Renin is the rate-limiting enzyme in a cascade that leads to production of angiotensin II, which is perhaps our most important regulator of salt and water balance and blood pressure. In this personal perspective, I describe how I entered the renin field 33 years ago by discovering that proteases increased the level of renin activity in biological fluids, so revealing the existence of a 'pro' form of the molecule. This led me on a journey that encapsulated all of the major milestones in molecular discovery for renin. These included (1) the elucidation of the steps in renin biosynthesis, (2) the cloning of renin cDNA and its gene, (3) demonstration of the structure of the renin protein, (4) using the renin gene in the first genetic studies in hypertension, (5) finding the mechanism by which the major controller, cyclic AMP, regulates the promoter, (6) showing that a strong enhancer and its weak promoter control this physiologically regulatable gene in accord with the variegation (on/off switching) model, and (7) being the first to identify molecules involved in posttranscriptional control. The renin molecule, its gene and molecular control are now very well understood, but more fine details on the topic of renin continue to emerge to delight 'reninologists' and others.

Scanning the genome for essential hypertension loci

1. Essential hypertension occurs in people with an underlying genetic predisposition who subject themselves to adverse environmental influences. The number of genes involved is unknown, as is the extent to which each contributes to final blood pressure and the severity of the disease. 2. In the past, studies of potential candidate genes have been performed by association (case-control) analysis of unrelated individuals or linkage (pedigree or sibpair) analysis of families. These studies have resulted in several positive findings but, as one may expect, also an enormous number of negative results. 3. In order to uncover the major genetic loci for essential hypertension, it is proposed that scanning the genome systematically in 100-200 affected sibships should prove successful. 4. This involves genotyping sets of hypertensive sibships to determine their complement of several hundred microsatellite polymorphisms. Those that are highly informative, by having a high heterozygosity, are most suitable. Also, the markers need to be spaced sufficiently evenly across the genome so as to ensure adequate coverage. 5. Tests are performed to determine increased segregation of alleles of each marker with hypertension. The analytical tools involve specialized statistical programs that can detect such differences. Non-parametric multipoint analysis is an appropriate approach. 6. In this way, loci for essential hypertension are beginning to emerge.

Some physiological outcomes of renin gene studies

1. The cloning of the renin gene has permitted studies of its physiological regulation, extrarenal expression and role in disease. 2. Marked modulation of renin mRNA concentration is seen in adrenal, heart and hypothalamus in response to sodium depletion and inhibition of AII formation, as well as in models of renal and genetic hypertension in the rat. 3. One important outcome of studies of the promoter has been the discovery of a cyclic AMP-responsive sequence. 4. Sequence variations have been detected in or near the renin gene and have been used as markers in studies of its role in cardiovascular disease aetiology. 5. In conclusion, molecular biology has, in the past decade, made a significant contribution to the understanding of renin physiology and pathophysiology.