Association of alpha-adducin Gly460Trp polymorphism with coronary artery disease in a Korean population

Gly460Trp polymorphism of the ADD1 gene and essential hypertension in an Indian population: A meta-analysis on hypertension risk

BACKGROUND:

Essential hypertension is a complex genetic trait. Genetic variant of alpha adducin (ADD1) gene have been implicated as a risk factor for hypertension. Given its clinical significance, we investigated the association between ADD1 Gly460Trp gene polymorphism and essential hypertension in an Indian population. Further, a meta-analysis was carried out to estimate the risk of hypertension.

METHODS:

In the current study, 432 hypertensive cases and 461 healthy controls were genotyped for the Gly460Trp ADD1 gene polymorphism. Genotyping was determined by real time PCR using Taqman assay. Multiple logistic regression analysis was used to detect the association between Gly460Trp polymorphism and hypertension.

RESULTS:

No significant association was found in the genotype and allele distribution of Gly460Trp polymorphism with hypertension in our study. A total of 15 case-control studies were included in the meta-analysis. There was no evidence of the association of Gly460Trp polymorphism with hypertension in general or in any of the sub group.

CONCLUSIONS:

We found that the Gly460Trp polymorphism is not a risk factor for essential hypertension in a south Indian Tamilian population. However, the role of ADD1 polymorphism may not be excluded by a negative association study. Further, large and rigorous case-control studies that investigate gene–gene–environment interactions may generate more conclusive claims about the molecular genetics of hypertension.

Adducin- and ouabain-related gene variants predict the antihypertensive activity of rostafuroxin, part 2: clinical studies

Twenty years of genetic studies have not contributed to improvement in the clinical management of primary arterial hypertension. Genetic heterogeneity, epistatic-environmental-biological interactions, and the pathophysiological complexity of hypertension have hampered the clinical application of genetic findings. In the companion article, we furnished data from rodents and human cells demonstrating two hypertension-triggering mechanisms--variants of adducin and elevated concentrations of endogenous ouabain (within a particular range)--and their selective inhibition by the drug rostafuroxin. Here, we have investigated the relationship between variants of genes encoding enzymes for ouabain synthesis [LSS (lanosterol synthase) and HSD3B1 (hydroxy-δ-5-steroid dehydrogenase, 3β- and steroid δ-isomerase 1)], ouabain transport {MDR1/ABCB1 [ATP-binding cassette, sub-family B (MDR/TAP), member 1]}, and adducin activity [ADD1 (adducin 1) and ADD3], and the responses to antihypertensive medications. We determined the presence of these variants in newly recruited, never-treated patients. The genetic profile defined by these variants predicted the antihypertensive effect of rostafuroxin (a mean placebo-corrected systolic blood pressure fall of 14 millimeters of mercury) but not that of losartan or hydrochlorothiazide. The magnitude of the rostafuroxin antihypertensive effect was twice that of antihypertensive drugs recently tested in phase 2 clinical trials. One-quarter of patients with primary hypertension display these variants of adducin or concentrations of endogenous ouabain and would be expected to respond to therapy with rostafuroxin. Because the mechanisms that are inhibited by rostafuroxin also underlie hypertension-related organ damage, this drug may also reduce the cardiovascular risk in these patients beyond that expected by the reduction in systolic blood pressure alone.

Personalized Medicine in Coronary Artery Disease: Insights From Genomic Research

Prior clinical studies have demonstrated that a family history of coronary artery disease (CAD) is associated with future cardiovascular events. Although there are several Mendelian disorders that are associated with CAD, most common forms of CAD are believed to be multifactorial and the result of many genes with small individual effects. The identification of these genes and their variation would be very helpful for the prediction, prevention, and management of CAD; linkage analysis or candidate gene case-control studies have been largely unsuccessful. On the contrary, recent advances in genomic techniques have generated a large amount of deoxyribonucleic acid (DNA)-based information. The link between CAD and inflammation and biological pathways has been highlighted. In particular, several genome-wide association studies have replicated a novel gene marker on chromosome 9p21. The information gained from genomic studies, in combination with clinical data, is expected to refine personalized approaches to assess risk and guide management for CAD. Genetic risk scores derived from several functional single nucleotide polymorphisms (SNPs) or haplotypes in multiple genes may improve the prediction of CAD. Despite the complexity of CAD genetics, steady progress is expected.

Physiological Interaction Between α-Adducin and WNK1-NEDD4L Pathways on Sodium-Related Blood Pressure Regulation

The kidney plays an important role in salt and blood pressure (BP) homeostasis. In previous studies, variants in the genes for α-adducin (ADD1), WNK1, and NEDD4L, which all regulate renal sodium absorption, have been associated with increased BP. However, findings have been inconsistent. We tested whether this is because of physiological interactions between the effects of variants in these genes. We assessed the single and combined effects of the ADD1 (Gly460Trp), WNK1 (rs880054 A/G), and NEDD4L (rs4149601 G/A) polymorphisms on renal and BP response to an acute Na load (n=344 subjects), BP decrease after 1 month of treatment with 12.5 mg of hydrochlorothiazide (n=193), and ambulatory 24-hour BP (n=690). Individually, the variants showed modest effects on some of the studied phenotypes. We found the ADD1 Trp allele to be permissive for the effects of variants of the other genes. In combination, the same variants (ADD1 Trp/WNK1 GG/Nedd4L GA+AA) showed a consistent effect on renal Na handling ( P =0.009) and acute BP response to a saline infusion ( P =0.021), BP lowering after thiazide treatment ( P =0.008), and nocturnal systolic BP ( P =0.044). Physiological interaction between the ADD1 and WNK1-NEDD4L pathways influences the effects of variants in these genes on sodium-related BP regulation. Relatively common alleles in the ADD1, WNK1, and NEDD4L genes when present in combination may have significant effects on renal sodium handling, BP, and antihypertensive response to thiazides.