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This article is part of the supplement: Genetic Analysis Workshop 16

Open Access Proceedings

Longitudinal age-dependent effect on systolic blood pressure

Bonnie R Joubert1*, Guoqing Diao2, Danyu Lin3, Kari E North14 and Nora Franceschini1

Author Affiliations

1 Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, 2101 McGavran-Greenberg Hall, CB #7435, Chapel Hill, North Carolina 27599, USA

2 Department of Statistics, George Mason University, 4400 University Drive, Fairfax, Virginia 22030, USA

3 Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, 2101 McGavran-Greenberg Hall, CB #7420, Chapel Hill, North Carolina 27599, USA

4 Carolina Center for Genome Sciences, University of North Carolina, 5009 Genetic Medicine Building, Chapel Hill, North Carolina 27599, USA

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BMC Proceedings 2009, 3(Suppl 7):S87  doi:

Published: 15 December 2009

Abstract

Age-dependent genetic effects on susceptibility to hypertension have been documented. We present a novel variance-component method for the estimation of age-dependent genetic effects on longitudinal systolic blood pressure using 57,827 Affymetrix single-nucleotide polymorphisms (SNPs) on chromosomes 17-22 genotyped in 2,475 members of the Offspring Cohort of the Framingham Heart Study. We used the likelihood-ratio test statistic to test the main genetic effect, genotype-by-age interaction, and simultaneously, main genetic effect and genotype-by-age interactions (2 degrees of freedom (df) test) for each SNP. Applying Bonferroni correction, three SNPs were significantly associated with longitudinal blood pressure in the analysis of main genetic effects or in combined 2-df analyses. For the associations detected using the simultaneous 2-df test, neither main effects nor genotype-by-age interaction p-values reached genome-wide statistical significance. The value of the 2-df test for screening genetic interaction effects could not be established in this study.