Genetic and Environmental Influences on Blood Pressure and Body Mass Index in the National Academy of Sciences–National Research Council World War II Veteran Twin Registry

Abstract

Blood pressure (BP) and obesity phenotypes may covary due to shared genetic or environmental factors or both. Furthermore, it is possible that the heritability of BP differs according to obesity status—a form of G×E interaction. This hypothesis has never been tested in White twins. The present study included 15 924 White male twin pairs aged between 15 and 33 years from the National Academy of Sciences–National Research Council World War II Veteran Twin Registry. Systolic and diastolic BPs, as well as height and weight, were measured at the induction physical examination. Body mass index (BMI) was used as the index of general obesity. Quantitative genetic modeling was performed using Mx software. Univariate analysis showed that narrow sense heritabilities (95% CI) for systolic BP, diastolic BP, height, and BMI were 0.401 (0.381–0.420), 0.297 (0.280–0.320), 0.866 (0.836–0.897), and 0.639 (0.614–0.664), respectively. Positive phenotypic correlations of BMI with systolic BP (r=0.13) and diastolic BP (r=0.08) were largely due to genetic factors (70% and 86%, respectively). The gene-BMI interaction analysis did not show any support for a modifying effect of BMI on genetic and environmental influences of systolic BP and diastolic BP. Our results suggest that correlations between BP and BMI are mainly explained by common genes influencing both. Higher BMI levels have no influence on the penetrance of genetic vulnerability to elevated BP. These conclusions may prove valuable for gene-finding studies.

Blood pressure and risk of cancer: a Mendelian randomization study

“…Fourth, the BP instruments were adjusted for BMI. Adjusting for an effect of the exposure does not necessarily create bias [ 72 ], correspondingly genetic estimates for BP have been shown to be similar with and without adjustment for BMI [ 73 ]. Using genetic instruments for BP without adjustment for BMI also made little difference to the estimate for total cancer.…”

Twin studies of cardiorespiratory disease, daily cardiovascular activity and imaging

“…These studies have shown that common genetic factors may for a large part explain the correlation of blood pressure components with BMI. [11][12][13][14] Blood pressure components were moderately correlated with BMI, largely because of shared genetic factors. However, for the association of BMI with brachial SBP and DBP, aortic SBP, and mean arterial pressure, acquired, modifiable factors were also found to be important.…”