Genes and Family Environment Explain Correlations Between Blood Pressure and Body Mass Index

Abstract

Abstract-The correlations between systolic blood pressure (SBP) and diastolic blood pressure (DBP), and between SBP and body mass index (BMI), might result from genetic or environmental factors that determine variation in 2 or more phenotypes and are shared by family members. In 767 adult nuclear families (nϭ2912 individuals, including 66 pairs of monozygotic twins and 84 pairs of dizygotic twins), we used a multivariate normal model and the software FISHER to estimate genetic and environmental components of variation and covariation. Mean phenotypes were adjusted for age, gender, and generation, and for antihypertensive treatment. Genetic and shared family environmental factors accounted for 46% and 31% of total variance in SBP, respectively. Adjustment of SBP for DBP reduced considerably both the additive genetic (86.7 to 21.0) and shared environmental (59.7 to 21.0) components of variance. Smaller reductions in genetic (86.7 to 84.9) and shared environmental (59.7 to 51.1) components were observed after adjustment of SBP for BMI. For SBP and DBP, the correlation between the effects of genes was 1.00 and between shared environmental effects was 0.52. For SBP and BMI the correlations were 0.30 for genetic and 0.22 for shared environmental effects. Our findings suggest that the same genes and many of the same family environmental factors determine variation in both SBP and DBP. In contrast, SBP and BMI share genetic and family environmental determinants to a lesser degree. These observations are relevant to multifactorial cardiovascular risk reduction based on genetic and family environmental approaches. (Hypertension. 2002;40:7-12.)Key Words: systole Ⅲ diastole Ⅲ body mass index Ⅲ genetics Ⅲ risk factors Ⅲ twins H igh blood pressure and body mass index (BMI) predispose independently to death from coronary artery disease and stroke. 1,2 However, hypertension and obesity also often coincide, and cardiovascular risk is augmented under these circumstances. The coincidence of these clinical conditions reflects the underlying correlation between blood pressure and body weight that has been observed at different ages and in a variety of populations. [3][4][5][6] Why there is an association between blood pressure and weight is unclear, although a number of specific physiological hypotheses have been advanced, 7 including the concept of insulin resistance and the metabolic syndrome. 8,9 If common causes of hypertension and obesity can be identified, they offer potentially important targets for more efficient and effective strategies for reduction in cardiovascular risk.Family and twin studies can provide evidence regarding genetic and environmental influences, not only on variation of individual traits, but also on covariation between traits. Such information will help direct molecular, clinical, and epidemiological searches for specific underlying causes. For example, evidence of genetic factors that determine both blood pressure and BMI might lead to more efficient and targeted molecular searches for the specific gene...

Genetic and environmental influences on body fat and blood pressure in African-American adult twins

“…We are only aware of a couple of studies, which used twins to provide heritability estimates for body fat and blood pressure. A study by Cui et al 16 found that genetic variance accounted for 46% of the total variance in SBP and environmental variance accounted for 31% of the total variance. When they adjusted SBP for BMI there was only a small decrease in the variance, 2% for genetic and 14% for environmental.…”

“…However, these results and others are hard to compare to the variance components analyses using only twins. 16,18,28 It may be that variance components analyses are not sensitive enough to determine these associations. There are some studies that have looked at specific gene effects, which may be common to blood pressure and body fat.…”

“…[13][14][15] A link between obesity and hypertension may be common genetic influences. Several family/twin studies (all among Caucasians) have found a common genetic influence, including a recent study by Cui et al 16 using twin pairs from the Victorian Family Heart Study. They found that genetic variance accounted for 46% of the total variance in SBP and common environment accounted for 31% of the total variance.…”

Relationship between a range of sedentary behaviours and blood pressure during early adolescence

“…2,3 Thus, the recognition and management of elevated BP at an early age may be an important strategy for limiting the overall disease burden caused by hypertension. 4,5 Factors such as genetics, 6 diet 7 and physical activity 8 appear to contribute to elevated BP in children. In addition, population-based studies have consistently shown that overweight/obese children have higher levels of BP and a higher prevalence of hypertension than their non-overweight/obese counterparts.…”

Sleep-disordered breathing and hypertension among African Americans

“…Emerging evidence, using both segregation analysis and a whole genome scan techniques, supports an underlying genetic basis for these conditions. [42][43][44][45][46][47][48][49] While studies are underway to examine these linkages, more effort should be made to encourage African-American patients to comply with existing therapies. Promoting the use of antihypertensive medications in this population has been challenging at best.…”