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

Nelson, Tracy L.; Brandon, Dwayne T.; Wiggins, Sebrina A.; Whitfield, Keith E.

doi:10.1038/sj.ijo.0803121

Cited by 9 publications

(8 citation statements)

References 32 publications

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“…Another study performed in African-American twins found sex differences, showing that 3.1% of the total variance in SBP was in common with BMI in males and 6% in females, while for DBP, 6.1% was in common with BMI in males and 3.7% in females. 10 The consistent results of these studies across different ethnicities and age groups confirm that part of the genetic variation in BP can be explained by genes for obesity.…”

Section: Discussionsupporting

confidence: 53%

Genetic and environmental influences on blood pressure and body mass index in Han Chinese: a twin study

Snieder

et al. 2010

Hypertens Res

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The familial aggregation of blood pressure (BP) may be partly due to the familial aggregation of obesity, caused by genetic and/or environmental factors that influence both. Gene-obesity interactions are expected to result in different heritability estimates for BP at different obesity levels. However, the latter hypothesis has never been tested. The present study included 1243 monozygotic and 833 dizygotic Han Chinese twins (mean±s.d. age: 37.81±9.82; range: 19.1-81.4) from the Chinese National Twin Registry. Body mass index (BMI) was used as the index of general obesity. The outcome measures were systolic BP (SBP) and diastolic BP (DBP). Quantitative genetic modeling was performed using Mx software. The SBP and DBP heritabilities were 46 and 30%, respectively. The positive correlations of BMI with SBP (r¼0.26) and with DBP (r¼0.27) were largely due to genetic factors (approximately 85%). Genetic factors, which also influence BMI, account for 6 and 7% of the total variance for SBP and DBP, respectively. The gene-obesity interaction analysis showed that both common and unique environmental influences on SBP increased with increasing levels of BMI, resulting in a lower heritability at higher BMI levels, whereas for DBP the heritability remained unchanged at higher BMI levels. Our results suggest that higher BMIs may reduce SBP heritability through a larger impact of environmental effects. These conclusions may be valuable for gene-finding studies. Keywords: blood pressure; heritability; interaction; obesity; twin INTRODUCTION Hypertension affects a large proportion of the adult population, 1 and is caused by complex interactions of environmental and genetic factors that vary across populations. Obesity is a well-established risk factor for hypertension. [2][3][4] Twin studies have shown that underlying continuous traits for both hypertension and obesity are significantly heritable. Heritability estimates for both systolic blood pressure (SBP) and diastolic blood pressure (DBP) are between 40 and 60%, 5 and the heritability for body mass index (BMI) is also substantial. 6-8 These estimates raise the possibility that common genetic susceptibility may account for the association. Several previous twin and family studies have shown that the association between blood pressure (BP) and BMI is partly attributed to a common set of genetic factors, 5,9-11 although another study investigating the differences in monozygotic (MZ) twins showed that even in the absence of genetic influences, obesity may still be significantly associated with BP. 12 Moreover, most of these studies

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Section: Discussionsupporting

confidence: 53%

Genetic and environmental influences on blood pressure and body mass index in Han Chinese: a twin study

Snieder

et al. 2010

Hypertens Res

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“…The best‐fitting model for EA female adolescents consisted of additive genetic, shared and nonshared environmental components (16). Other studies conducted with AA samples have not found a significant nonadditive genetic effect, but these samples were smaller than that in this study and would not have had the statistical power to detect nonadditive genetic effects (9,10). Power analyses for the univariate case (estimated using standard asymptotic methods using the noncentral χ 2 distribution, assuming negligible shared environmental contributions to variations in AA pairs) demonstrated sufficient statistical power in the current AA sample (293 pairs with either wave 1 or wave 4 data ‐ including 121 MZ pairs) to detect a significant nonadditive genetic effect for a trait as strongly familial as BMI ( r MZ = 0.65 at baseline and r MZ = 0.78 at follow‐up).…”

Section: Discussioncontrasting

confidence: 70%

“…Furthermore, the majority of previous studies have been conducted on twins of European descent. Those studies that have used AA twin pairs have been conducted on relatively small samples that included individuals of both sexes and over a broad age range and have focused on BMI at a single time point (9,10). Therefore, we sought to determine the genetic and environmental contributions to BMI over time in a sample of adolescent and young adult female twins and to determine whether these contributions differed by race.…”

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confidence: 99%

Genetic and Environmental Contributions to BMI in Adolescent and Young Adult Women

Duncan

Agrawal

Grant

et al. 2009

Obesity

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The objective of this study was to determine the genetic and environmental contributions to variation in BMI over time in European‐American (EA) and African‐American (AA) adolescent and young adult women. Self‐reported BMI (kg/m2) data from 2,816 EA (1,306 twin pairs, 56.5% monozygotic (MZ)) and 404 AA (178 twin pairs, 42.7% MZ) women at baseline (T1; median age 15 years) and 3,225 EA (1,511 twin pairs, 55.3% MZ) and 539 AA (252 pairs, 43.3% MZ) women at follow‐up (T2; median age 22 years) from a Midwestern US, population‐based twin registry were used to construct biometrical genetic models. For EA women, the majority of the variance in BMI was attributable to additive genetic effects at both time points (82% for each), with the remaining variance attributable to nonshared environment. Genetic and nonshared environment correlations between adolescent and young adult BMI were 0.87 and 0.23, respectively. Among AA women, nonadditive genetic effects comprised 68% of the variance at T1 and 73% at T2, and were highly correlated (rD = 0.94). The proportions of variance attributable to nonshared environment at T1 (29%) and T2 (25%) were more modestly correlated (rE = 0.31). The remaining variance in AA women could be attributed to additive genetic effects. Additive vs. nonadditive genetic effects contribute differentially to BMI in AA vs. EA adolescent and young adult women. Additional research is needed to better characterize the environmental and genetic factors related to BMI in persons of different races to aid understanding of the complex determinants of body weight in individuals.

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“…A total of 88 independent estimates of BMI heritability from twin studies were identified from 31 papers (Stunkard et al, 1986, 1990; Hewitt et al, 1991; Korkeila et al, 1991; Neale and Cardon, 1992; Carmichael and McGue, 1995; Forbes et al, 1995; Harris et al, 1995; Herskind et al, 1996; Austin et al, 1997; Faith et al, 1999; Knoblauch et al, 1999; Narkiewicz et al, 1999; Pietilainen et al, 1999; Vinck et al, 1999; Baird et al, 2001; Poulsen et al, 2001; Schousboe et al, 2003, 2004; Nelson et al, 2006; Cornes et al, 2007; Hur, 2007; Ordonana et al, 2007; Silventoinen et al, 2007a,b; Souren et al, 2007; Hur et al, 2008; Liu et al, 2008; Wardle et al, 2008; Lajunen et al, 2009; Watson et al, 2010; Table 1; Figure A2 in Appendix). Reported estimates ranged from 0.47 to 0.90 (5th/50th/95th centiles: 0.58/0.75/0.87; Figure 1).…”

Section: Resultsmentioning

confidence: 99%

Variability in the Heritability of Body Mass Index: A Systematic Review and Meta-Regression

Elks¹,

Hoed²,

Zhao³

et al. 2012

Front. Endocrin.

511

404

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Evidence for a major role of genetic factors in the determination of body mass index (BMI) comes from studies of related individuals. Despite consistent evidence for a heritable component of BMI, estimates of BMI heritability vary widely between studies and the reasons for this remain unclear. While some variation is natural due to differences between populations and settings, study design factors may also explain some of the heterogeneity. We performed a systematic review that identified 88 independent estimates of BMI heritability from twin studies (total 140,525 twins) and 27 estimates from family studies (42,968 family members). BMI heritability estimates from twin studies ranged from 0.47 to 0.90 (5th/50th/95th centiles: 0.58/0.75/0.87) and were generally higher than those from family studies (range: 0.24–0.81; 5th/50th/95th centiles: 0.25/0.46/0.68). Meta-regression of the results from twin studies showed that BMI heritability estimates were 0.07 (P = 0.001) higher in children than in adults; estimates increased with mean age among childhood studies (+0.012/year, P = 0.002), but decreased with mean age in adult studies (−0.002/year, P = 0.002). Heritability estimates derived from AE twin models (which assume no contribution of shared environment) were 0.12 higher than those from ACE models (P < 0.001), whilst lower estimates were associated with self reported versus DNA-based determination of zygosity (−0.04, P = 0.02), and with self reported versus measured BMI (−0.05, P = 0.03). Although the observed differences in heritability according to aspects of study design are relatively small, together, the above factors explained 47% of the heterogeneity in estimates of BMI heritability from twin studies. In summary, while some variation in BMI heritability is expected due to population-level differences, study design factors explained nearly half the heterogeneity reported in twin studies. The genetic contribution to BMI appears to vary with age and may have a greater influence during childhood than adult life.

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

Cited by 9 publications

References 32 publications

Genetic and environmental influences on blood pressure and body mass index in Han Chinese: a twin study

Genetic and environmental influences on blood pressure and body mass index in Han Chinese: a twin study

Genetic and Environmental Contributions to BMI in Adolescent and Young Adult Women

Variability in the Heritability of Body Mass Index: A Systematic Review and Meta-Regression

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