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Genome scan linkage results for longitudinal systolic blood pressure phenotypes in subjects from the Framingham Heart

Katherine James1, Lindsay-Rae B Weitzel, Corinne D Engelman

  • 1Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver, Colorado, USA. Kathy.James@uchsc.edu

BMC Genetics
|February 21, 2004
PubMed

Insights

This study identified a genetic linkage on chromosome 1 associated with systolic blood pressure (SBP) variation. Analyzing Framingham Heart Study data, researchers developed a novel phenotype to pinpoint genetic influences on SBP.

Area of Science:

  • Genetics
  • Cardiovascular Epidemiology
  • Biostatistics

Background:

  • Elevated blood pressure, particularly systolic blood pressure (SBP), is a significant risk factor for cardiovascular and cerebrovascular diseases.
  • Systolic blood pressure (SBP) is a more critical determinant of cardiovascular risk than diastolic blood pressure.
  • Understanding the genetic underpinnings of SBP variability is crucial for developing targeted interventions.

Purpose of the Study:

  • To identify genetic loci associated with systolic blood pressure (SBP) using a novel phenotype derived from the Framingham Heart Study.
  • To characterize individual SBP trajectories over time using mixed modeling, accounting for covariates like age, gender, BMI, and hypertension treatment.
  • To investigate the linkage between this individualized SBP phenotype and genetic markers.

Main Methods:

  • Utilized the Framingham Heart Study dataset, selecting clinical data including SBP, age, height, gender, weight, and hypertension treatment.
  • Employed linear mixed modeling to define an individualized SBP phenotype, representing deviation from the population average SBP change per year.
  • Performed linkage analysis to associate the normalized SBP phenotype with chromosomal regions, specifically examining chromosome 1.

Main Results:

  • A significant linkage (p = 0.00002) was detected between the normalized SBP phenotype and a region on chromosome 1.
  • Similar linkage results were observed even when excluding SBP measurements taken during hypertension treatment, suggesting robustness.
  • The mixed modeling approach effectively adjusted for covariates, providing a refined phenotype for genetic analysis.

Conclusions:

  • The study provides evidence for a genetic locus on chromosome 1 influencing systolic blood pressure (SBP) variation.
  • Linear mixed models offer a valuable methodology for defining complex phenotypes like SBP trajectories for genetic studies.
  • Future research should integrate phenotype estimation more directly into linkage analysis to account for estimation error.

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