Exclusion of angiotensinogen gene in molecular basis of human hypertension: Sibpair linkage and association analyses in Australian Anglo-Caucasians

Abstract

Linkage with essential hypertension has been claimed for a microsatellite marker near the angiotensinogen gene (AGT; chromosome 1q42), as has association for the AGT variants M235T, G(-6)A and A(-20)C. To more rigorously evaluate AGT as a candidate gene for hypertension we performed sibpair analysis with multiple microsatellite markers surrounding this locus and using more sophisticated analysis programs. We also performed an association study of the AGT variants in unrelated subjects with a strong family history (two affected parents). For the linkage study, single and multiplex polymerase chain reaction (PCRs) and automated genescan analysis were conducted on DNA from 175 Australian Anglo-Celtic Caucasian hypertensives for the following markers: D1S2880-(2.1 cM)-D1S213-(2.8 cM)-D1S251-(6.5 cM)-AGT-(2.0 cM) -D1S235. Statistical evaluation of genotype data by nonparametric methods resulted in the following scores: Single-point analysis - SPLINK, P > 0.18; APM method, P > 0.25; ASPEX, MLOD < 0.28; SIB-PAIR, P > 0. 24; Multipoint analysis - MAPMAKER/SIBS, MLOD < 0.24; GENEHUNTER, P > 0.35. Exclusion scores of Lod -4.1 to -5.1 were obtained for these markers using MAPMAKER/SIBS for a lambda(s) of 1.6. The association study of G(-6)A, A(-20)C and M235T variants in 111 hypertensives with strong family history and 190 normotensives with no family history showed significant linkage disequilibrium between particular haplotypes, but we could find no association with hypertension. The present study therefore excludes AGT in the etiology of hypertension, at least in the population of Australian Anglo-Celtic Caucasians studied.

Effects of the angiotensinogen gene M235T and A(-6)G variants on blood pressure and other vascular risk factors in a Spanish population

“…These findings stress the necessity of considering ethnic factors in the assessment of genetic risk identifiers. Also Wang et al, 19 have reported controversial results with AGT gene in a hypertensive Australian population.…”

“…33 An absence of association has been observed in Africans, 14,16 in Chinese 34,35 and in the Australian population. 19 In the meta-analysis of Kunz et al, 10 which includes 5493 patients, carried out in a white population, the estimated associated risk to the allele 235T was 1.2 (95% Cl, 1.11 to 1.29; P Ͻ 0.0001). The risk increased when we considered the family history of AH or the AH was stratified, but different bias were also reported in the studies analysed which reflected, for example, defects in their selection of the sample size or lack of homogeneity in the population studied.…”

“…Through case-control studies, the Threonine allele (235T) of M235T have been associated with elevated risk of hypertension, 3,8,10,11,15 in some populations, but not in others. 6,13,[16][17][18][19] The M235T polymorphism has been shown to be in very tight linkage disequilibrium with a variation known as A(-6)G. This involves a swap of adenine to guanine six nucleotides upstream from the site of transcription initiation in the AGT promoter. 20,21 Although M235T polymorphism is associated with plasma angiotensinogen level variation it does not seem to have a functional role; however A(-6) is known to affect the basal rate of the AGT gene transcription.…”

Renin–angiotensin system gene polymorphisms: relationship with blood pressure and microalbuminuria in telmisartan-treated hypertensive patients

“…The A-6G polymorphism located in the promoter region of the AGT gene was analyzed using the method described by Wang et al 27 The 3 0 promoter region was amplified with oligonucleotides 5 0 -GAG GTC CCA GCG TGA GTG TCG C and 5 0 -CTC AGT TAC ATC CTG AGA GAG ACA AGA CC under standard PCR conditions. Fragments were analyzed by SSCP using water-cooled vertical minigels (10 Â 10 cm 2 ).…”

Association of A-20C polymorphism in the angiotensinogen gene with essential hypertension: a meta-analysis

“…Ten publications were included in the final meta-analysis (Ishigami et al, 1997;Wang et al, 1999;Sato et al, 2000;Tsai et al, 2003;Velez et al, 2006;Niu et al, 2007;Qi et al, 2008;Jiang et al, 2009;Ying et al, 2010;Li et al, 2013) based on the above-mentioned inclusion and exclusion criteria. Details of the selection process are presented in the flow chart in Figure 1.…”