Lack of association of the angiotensinogen-6 polymorphism with blood pressure levels in the comprehensive NHLBI Family Blood Pressure Program. National Heart, Lung and Blood Institute.
OBJECTIVE
To evaluate the association between the angiotensinogen-6 polymorphism (AGT-6) and blood pressure levels.


METHODS
Data were analysed from the first 4,322 subjects of the NHLBI Family Blood Pressure Program (FBPP), consisting of four networks (GenNet, GENOA, HyperGEN and SAPPHIRe), each conducting a multicentre observational family study to identify and characterize the genetic determinants of hypertension and blood pressure. The four studies use different designs (concordant sibpairs, discordant pairs, sibships, extended pedigrees), target different ethnic groups (Caucasian, African-American, Japanese, Chinese), and have different inclusion/exclusion criteria. However, the protocols and definitions were standardized across networks before data collection to allow maximum poolability.


METHODS
Each network/racial group was analysed separately, using generalized linear models that accounted for the non-independence of family members and/or the confounding of anti-hypertensive medications as needed. The results were also pooled using a pre-planned meta-analysis technique.


RESULTS
AGT-6 was not significantly associated with blood pressure in any network/racial group. In the meta-analysis, the pooled effect of AGT-6 was small [hazard ratio = 1.10, 95% confidence interval (CI) = 0.99-1.22, P= 0.0647 for systolic; hazard ratio = 1.04, 95% CI = 0.89-1.21, P= 0.6383 for diastolic]. A post-hoc analysis restricting to subjects meeting JNC VI criteria for Stage I hypertension (blood pressure > 140/90 mmHg or medicated) showed a stronger statistically significant relationship for systolic blood pressure (hazard ratio = 1.44, 95% CI = 1.04-2.00, P= 0.0283).


CONCLUSIONS
AGT-6 has minimal to no effect on the inter-individual variation of blood pressure levels, and is at best a 'minor gene' for blood pressure in the population as a whole.
Division of Biostatistics, Washington University School of Medicine, St Louis, Missouri 63110, USA. mike@wubios.wustl.edu
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Province
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Boerwinkle
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Chakravarti
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Cooper
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Fornage
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Leppert
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Risch
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Ranade
D000293:Adolescent; D000328:Adult; D000808:Angiotensinogen / Q000235:genetics*; D044466:Asian People / Q000235:genetics; D044383:Black People / Q000235:genetics; D001794:Blood Pressure / Q000502:physiology*; D004247:DNA / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D006973:Hypertension / Q000208:ethnology / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000235:genetics*; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D016016:Proportional Hazards Models; D013624:Taiwan / Q000453:epidemiology; D014481:United States / Q000453:epidemiology; D044465:White People / Q000235:genetics; D001741:Black or African American
D010446:Peptide Fragments; D000808:Angiotensinogen; C055796:angiotensinogen (6-13); D004247:DNA