Objective: To investigate the contribution of the mitochondrial genome to hypertension and quantitative blood pressure (BP) phenotypes in the Framingham Heart Study cohort, a randomly ascertained, community-based sample.
Methods: Longitudinal BP values of 6421 participants (mean age, 53 years; 46% men) from 1593 extended families were used for analyses. In analyses of BP as a continuous trait, a variance components model with a variance component for maternal effects was used to estimate the mitochondrial heritability of the long-term average BP adjusted for age, sex, body mass index, and hypertension treatment. For analyses of BP as a categorical trait, a nonparametric test sensitive to excessive maternal inheritance was used to test for mitochondrial effect on long-term hypertension, defined as systolic BP of at least 140 mmHg or diastolic BP of at least 90 mmHg or use of antihypertensive medication in one-half or more of qualifying examinations. This test was based on 353 pedigrees comprised of 403 individuals informative for mitochondrial DNA contribution.
Results: The estimated fraction of hypertensive pedigrees potentially due to mitochondrial effects was 35.2% (95% confidence interval, 27-43%, P < 10). The mitochondrial heritabilities for multivariable-adjusted long-term average systolic BP and diastolic BP were, respectively, 5% (P < 0.02) and 4% (P = 0.11).
Conclusion: Our data provide support for a maternal effect on hypertension status and quantitative systolic BP, consistent with mitochondrial influence. Additional studies are warranted to identify mitochondrial DNA variant(s) affecting BP.