Genetic Heritability and Common Environmental Components of Resting and Stressed Blood Pressures, Lipids, and Body Mass Index in Utah Pedigrees and Twins

Abstract

The relative contributions of genes and shared environment to cardiovascular risk factors were studied in twins and pedigrees in 1983-1985. Sitting, standing, isometric hand grip, bicycling, and mentally stressed (serial subtraction) blood pressures were obtained from 146 male monozygous twins, 162 male dizygous twins, and 1,102 healthy adults in 67 Utah pedigrees. Fasting total plasma cholesterol, triglycerides, high density lipoprotein cholesterol (HDL), and body mass index were also measured. Heritability was estimated before and after adjusting for 12 environmental variables (measures of socioeconomic status; personality types; exercise levels; use of tobacco, alcohol, coffee, etc.) by using age-adjusted twin intraclass correlations. These heritabilities were compared with those obtained from a variance components analysis of the pedigree data separating genetic and common household effects. Sitting and standing blood pressure heritability estimates were much higher from twin than from pedigree data (39-63% in twins vs. 16-22% in pedigrees), as were those for cholesterol and triglycerides (65 and 75% from twins vs. 42 and 37% from pedigrees) and body mass index (51 vs. 21%). Estimates were similar for heritability of HDL cholesterol (51 vs. 45%). Most of the stressed blood pressure heritabilities were similar to sitting blood pressure estimates. No common household effect (except for adjusted HDL cholesterol (24%), p less than 0.01) was statistically significant for the lipids, blood pressures, or body mass index. Environmental variables correlated much better in monozygous twins and spouses than in dizygous twins, brothers, or sisters. Spouse correlations for lipids, blood pressures, and body mass index were low, with a maximum of 0.12 (p less than 0.05) for HDL cholesterol. We conclude that genes contribute much more than shared environment to the well-recognized familial correlation of blood pressures, lipids, and body mass index.

Quantitative genetic analysis of blood pressure reactivity to orthostatic tilt using principal components analysis

“…Our heritability estimates for BP during HUT fall in the middle of the range reported by others. Hunt et al 42 found heritability estimates for standing BP that ranged from 0.08 to 0.16 for SBP and from 0.11 to 0.21 for Our results from the PCA indicate that multiple measurements of BP can be reduced to three interpretable components that represent (1) the overall effects of BP at rest and during HUT (i.e., 'general BP'), (2) 'pulse pressure' and (3) 'BP reactivity'. The three extracted components represent different aspects of BP during HUT such that each of these factors is distinct and uncorrelated with the others.…”

The contribution of genes, environment and of body mass to blood pressure variance in young adult males

“…We analysed all studies on BP heritability including subjects older than 5 years of age, where mean age was reported and a Falconer heritability estimate 28 could be computed. 26,[29][30][31][32][33][34][35][36][37][38] These estimates are plotted versus age in Figure 3, which also shows the fit from the locally-weighted regression analysis. 39,40 The amount of fitting that was done, is equivalent to 4 degrees of freedom.…”

“…Especially a direct effect of BMI on BP could lead to an overestimation of BP heritability, 9 since BMI itself is highly heritable. 11 Because of this, it is very important to disentangle the influence of BMI, genetic influences and environmental influences in the variance of BP. Allison et al 10 have elegantly shown in middle-aged women how multivariate genetic modelling of twin data can be used to put the impact of an influence of BMI on BP into perspective with the genetic and environmental influences on BP per se.…”

Novel rare alleles of ABCA1 are exclusively associated with extreme high-density lipoprotein-cholesterol levels among the Han Chinese

“…Low concentrations of HDL-cholesterol (HDL-C) are a strong and independent risk factor for coronary heart disease (1). About 50% of the variation in plasma level HDL-C is believed to be genetically determined (2,3). ATP binding cassette transporter 1 gene (ABCA1, Genbank ID NM_005502, alias: ABC1; CERP; ABC-1) is one of the major genes modulating plasma HDL-C concentrations, and underlies two genetic diseases with low HDL-C: Tangier disease (MIM 205400) and familial HDL deficiency (MIM 604091) (4).…”