Novel variants detected in AGT gene among patients with essential hypertension.

INTRODUCTION: AGT is the first gene to be linked to essential hypertension (EHT). It harbors several variants of which only few polymorphisms are found to exhibit positive and negative associations with hypertension. In the present study, the AGT gene was screened to detect already reported and novel variations contributing to the development of hypertension. METHOD: In total, 215 hypertensives and 230 normotensives were screened for variations in all the five exons and a part of promoter of AGT gene using single strand conformation polymorphism analysis followed by sequencing of samples showing mobility shifts on polyacrylamide gels. RESULTS: Five novel variants, namely c.-61G>A in promoter, c.-4+17C>T in intron1, c.24T>C and c.28A>T in Exon2, and c.*90 T>C in 3' untranslated region were detected in the AGT gene. c.-61G>A lies in the promoter region that plays a critical role in its expression. Variation c.-4+17C>T created a new enhancer site. c.24T>C (TCT-TCC) is a silent mutation while c.28A>T (p. M10L) has a possible damaging effect on the AGT protein. c.*90T>C, detected in the 3' untranslated region is thought to play an important role in the translation and stability of the mRNA. CONCLUSION: Studies on the functional role of these novel variants are warranted to understand the mechanism underlying the development of EHT.

Risk conferred by tagged SNPs of AGT gene in causing susceptibility to essential hypertension.

UNLABELLED: Abstract Introduction: AGT gene harbors several variants of which 21 are found to be in high linkage disequilibrium as per Hapmap database. Studies delineating the importance of these tagged SNPs are very limited and lacking from Indian population. In the present study, we evaluated the contribution of four tagged SNPs namely, g.6635G > A, g.6506G > A, g.12840G > A, and g.13828T > C at AGT locus along with the analyses of haplotype and epistatic interactions in causing susceptibility to essential hypertension (EHT). METHODS: About 215 hypertensives and 230 normotensives were genotyped for selected tagged SNPs using PCR-RFLP method. RESULTS: Significant association was obtained for g.6635G > A and g.6506G > A polymorphisms wherein GG homozygotes for both the markers were at risk for developing the condition. g.13828T > C polymorphism specially, female heterozygotes (TC) were found to be at increased risk for EHT. Haplotype GGGC was found to have a significant protective effect (p = 0.0059). Markers g.6506G > A and g.12840G > A resulted in the creation of new enhancer sites thereby affecting splicing process. CONCLUSION: The present report is the first one in the literature showing general- and gender-specific association of g.6506G > A and g.13828T > C polymorphisms, respectively, with EHT. However, further studies for replication of present observations are warranted from other populations and other parts of India.

Estimation of risk and interaction of single nucleotide polymorphisms at angiotensinogen locus causing susceptibility to essential hypertension: a case control study.

INTRODUCTION: The risk conferred by the variants and haplotypes of single nucleotide polymorphisms (SNPs) at human angiotensinogen (AGT) gene to essential hypertension (EHT) have been described in several populations with variations in the results attributed to their ethnicity. We attempted to evaluate the risk of -217G>A, -152G>A, -20A>C, -6G>A, T174M, M235T and 15241A>G polymorphisms at AGT locus along with the analyses of haplotype and epistatic interactions in causing susceptibility to EHT. METHOD: Two-hundred and forty-nine hypertensives and 248 controls were genotyped for the selected markers. RESULTS: Study of demographic parameters revealed significant association of obesity, positive family history and non-vegetarian diet habit, suggesting elevated risk of the condition when associated with these parameters. Significantly high risk for males with AA genotype of -217G>A polymorphism was observed for developing EHT (p = .07). Males with -217A (p = .01) showed a two-fold higher risk for EHT. Markers -217G>A and -6G>A were in strong linkage disequilibrium in patients as compared to controls. Strong epistatic interactions were found between -6G>A, M235T and -217G>A markers, supporting the synergistic effect between them leading to EHT. CONCLUSION: Our findings suggest that -217A variant is significantly associated with the risk for EHT in males. Further studies on the functional role of the marker -217 are recommended for understanding the cause of association with EHT.