Heritability of Caffeine Metabolism: Environmental Effects Masking Genetic Effects on CYP1A2 Activity but Not on NAT2

2016 ◽  
Vol 100 (6) ◽  
pp. 606-616 ◽  
Author(s):  
J Matthaei ◽  
MV Tzvetkov ◽  
J Strube ◽  
D Sehrt ◽  
C Sachse-Seeboth ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Genetic Effects ◽  
Cyp1a2 Activity ◽  
Caffeine Metabolism

scholarly journals Twin Analyses of Fatigue

2007 ◽  
Vol 10 (5) ◽  
pp. 729-733 ◽  
Author(s):  
Ellen Schur ◽  
Niloofar Afari ◽  
Jack Goldberg ◽  
Dedra Buchwald ◽  
Patrick F. Sullivan
Keyword(s):  
Environmental Effects ◽  
Structural Equation ◽  
Environmental Influences ◽  
Twin Studies ◽  
Chronic Fatigue ◽  
Genetic Effects ◽  
Fatigue Syndrome ◽  
Prolonged Fatigue ◽  
The University ◽  
Twin Modeling

AbstractProlonged fatigue equal to or greater than 1 month duration and chronic fatigue equal to or greater than 6 months duration are both commonly seen in clinical practice, yet little is known about the etiology or epidemiology of either symptom. Chronic fatigue syndrome (CFS), while rarer, presents similar challenges in determining cause and epidemiology. Twin studies can be useful in elucidating genetic and environmental influences on fatigue and CFS. The goal of this article was to use biometrical structural equation twin modeling to examine genetic and environmental influences on fatigue, and to investigate whether these influences varied by gender. A total of 1042 monozygotic (MZ) twin pairs and 828 dizygotic (DZ) twin pairs who had completed the University of Washington Twin Registry survey were assessed for three fatigue-related variables: prolonged fatigue, chronic fatigue, and CFS. Structural equation twin modeling was used to determine the relative contributions of additive genetic effects, shared environmental effects, and individual-specific environmental effects to the 3 fatigue conditions. In women, tetrachoric correlations were similar for MZ and DZ pairs for prolonged and chronic fatigue, but not for CFS. In men, however, the correlations for prolonged and chronic fatigue were higher in MZ pairs than in DZ pairs. About half the variance for both prolonged and chronic fatigue in males was due to genetic effects, and half due to individual-specific environmental effects. For females, most variance was due to individual environmental effects.

The Heritability of Life Events: An Adolescent Twin and Adoption Study

2008 ◽  
Vol 11 (3) ◽  
pp. 257-265 ◽  
Author(s):  
Heather R. Bemmels ◽  
S. Alexandra Burt ◽  
Lisa N. Legrand ◽  
William G. Iacono ◽  
Matt McGue
Keyword(s):  
Life Events ◽  
Environmental Effects ◽  
Twin Studies ◽  
Specific Effect ◽  
Genetic Effects ◽  
Adolescent And Young Adult ◽  
Adoption Study ◽  
Independent Events ◽  
Biometrical Models ◽  
Additive Genetic Effects

AbstractAlthough life events are often conceptualized as reflecting exogenous risk factors for psychopathology, twin studies have suggested they are heritable. We undertook a mixed twin/adoption study to further explore genetic and environmental contributions to individual differences in the experience of life events. Specifically, a sample of 618 pairs of like-sex adolescent twins, 244 pairs of like-sex adopted adolescent and young adult siblings, and 128 pairs of like-sex biological siblings completed a life events interview. Events were classified as independent (not likely to have been influenced by respondent's behavior), dependent (likely to have been influenced by respondent's behavior), or familial (experienced by a family member), and then summed to form three life event scales. Variance on the scales was assumed to be a function of four factors: additive genetic effects (a2), shared environmental effects (c2), twin-specific effects (t2), and nonshared environmental effects (e2). Data were analyzed using standard biometrical models. Shared environmental effects were found to be the largest contributor to variance in familial events (c2 = .71; 95% confidence interval of .65, .76); additive genetic effects were the largest contributor to dependent events (a2 = .45; CI = .31, .58); and nonshared environmental effects were found to be the largest contributor independent events (e2 = .57; CI = .51, .64). A significant twin-specific effect was also found for independent life events, indicating that twins are more likely to be exposed to such events than non-twin biological siblings. Findings are discussed in terms of their implication for understanding the nature of psychosocial risk.

Genetic parameters of growth in rainbow trout, Salmo gairdneri, prior to maturation

1986 ◽  
Vol 28 (2) ◽  
pp. 306-312 ◽  
Author(s):  
L. R. McKay ◽  
P. E. Ihssen ◽  
G. W. Friars
Keyword(s):  
Rainbow Trout ◽  
Maternal Effects ◽  
Environmental Effects ◽  
Condition Factor ◽  
Relative Magnitude ◽  
Genetic Effects ◽  
Salmo Gairdneri ◽  
Family Selection ◽  
Egg Weight ◽  
Heritability Estimates

The relative magnitude of additive genetic effects, nonadditive genetic effects, maternal effects, and common environmental effects was determined for size, growth, and condition factor in rainbow trout of various ages, from the egg to the yearling stage, using a factorial mating system. Heritability estimates for length and weight ranged from 0.09 to 0.32, except for dried egg weight, where no additive genetic variation was detected. Condition factors were more heritable than size, with heritability estimates ranging from 0.24 to 0.46. Maternal effects were only important for dried egg weight and early fry size, and decreased rapidly with age as heritability increased. Egg weight, fry size, and fry condition factors were influenced by common environmental effects and (or) nonadditive genetic effects, but confounding of these sources of variation prevented exact estimation of their relative magnitude. Nonadditive genetic effects were completely absent for yearling size but were present for yearling condition factors. Individual or between-family selection on size should produce some response unless selection is done on very young fry or families are housed separately. For very young fry or where families are not replicated across tanks, within-family selection will be necessary to identify genetically superior fish, because of strong maternal or common environmental effects. Genetic correlations between size or condition factors measured at different ages were all positive, so selection at one stage should improve size or condition factor at another.Key words: rainbow trout, growth, heritability, maternal effects, genetics.

A Genetic Analysis of Taste Threshold for Phenylthiocarbamide

1981 ◽  
Vol 30 (1) ◽  
pp. 51-57 ◽  
Author(s):  
C. C. Morton ◽  
R. M. Cantor ◽  
L. A. Corey ◽  
W. E. Nance
Keyword(s):  
Genetic Analysis ◽  
Maternal Effects ◽  
Environmental Effects ◽  
Environmental Parameters ◽  
Genetic Effects ◽  
Broad Sense Heritability ◽  
Taste Threshold ◽  
Confidence Levels ◽  
Jackknife Procedure ◽  
Additive Genetic Effects

Taste threshold for phenylthiocarbamide (PTC) was measured in 393 offspring from the families of 85 monozygotic (MZ) twin pairs. PTC scores were bimodally distributed with modes at one and eight and the antimode at five. Because of the non-normality of the distribution, a jackknife procedure was used to obtain 95% confidence intervals for the estimates of genetic, maternal, and environmental parameters. Analyses which assumed no epistasis and which included additive genetic effects revealed that 37.9% of the observed variation in PTC threshold was due to additive genetic effects, 16.6% was due to dominance effects, 14.2% was due to maternal effects, 13.7% was due to a common sibship environment, and 17.6% was due to random environmental effects, yielding a broad sense heritability of 0.55 for the threshold ability to taste PTC. Analyses which did not include additive genetic effects revealed 26.6% of the observed variance was due to dominance effects, 23.6% to maternal effects, and 49.8% to environmental effects at the 0.67 confidence levels, but that environmental factors accounted for 72.4% and dominance effects for 23.6% of the observed variation at the 95% level.

Modeling Extended Twin Family Data II: Power Associated With Different Family Structures

2009 ◽  
Vol 12 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Sarah E. Medland ◽  
Matthew C. Keller
Keyword(s):  
Assortative Mating ◽  
Environmental Effects ◽  
Cultural Transmission ◽  
Statistical Power ◽  
Large Data ◽  
Genetic Effects ◽  
Data Sets ◽  
Family Structures ◽  
Nonrandom Mating ◽  
Children Of Twins

AbstractModeling the data from extended twin pedigrees allows the estimation of increasing complex covariance relationships in which the effects of cultural transmission, nonrandom mating and genotype x environment covariation can be incorporated. However, the power to detect these effects in existing data sets has not yet been examined. The present study examined the effects that different family structures (i.e., the ratio of MZ to DZ families and the importance of cousins vs. avuncular relatives) have on statistical power. In addition, we examined the power to detect genetic and environmental effects within the context of two large data sets (VA30K and the OZVA60K). We found that power to detect additive genetic and cultural transmission effects were maximized by over sampling MZ families. In terms of ascertainment, there was little difference in power between samples that had focused on recruiting a third generation (the children of twins) versus those that had focused on recruiting the siblings of the twins. In addition, we examined the power to detect additive and dominant genetic effects, cultural transmission and assortative mating in the existing VA30K and OZVA60K samples, under two different models of mating: phenotypic assortment and social homogamy. There was nearly 100% power to detect assortative mating and cultural transmission, against a background of small additive and dominant genetic and familial environmental effects. In addition, the power to detect additive or dominant genetic effects quickly asymptoted, so that there was almost 100% power to detect effects explaining 20% or more of the total variance. These results demonstrate that the Cascade model has sufficient power to detect parameters of interest in existing datasets. Mx scripts are available from www.vipbg.vcu.edu/~sarahme/cascade.

scholarly journals Shared genetics and couple-associated environment are major contributors to the risk of both clinical and self-declared depression

2016 ◽  
Author(s):  
Yanni Zeng ◽  
Pau Navarro ◽  
Charley Xia ◽  
Carmen Amador ◽  
Ana M. Fernandez-Pujals ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Genetic Variants ◽  
Environmental Effect ◽  
Genetic Effect ◽  
Health Department ◽  
Genetic Effects ◽  
Common Genetic Variants ◽  
Scottish Government ◽  
Family Based ◽  
Major Factors

AbstractBackgroundBoth genetic and environmental contributions to risk of depression have been identified, but estimates of their effects are limited. Commonalities between major depressive disorder (MDD) and self-declared depression (SDD) are also unclear. Dissecting the genetic and environmental contributions to these traits and their correlation would inform the design and interpretation of genetic studies.MethodsUsing data from a large Scottish family-based cohort (GS:SFHS, N=21,387), we estimated the genetic and environmental contributions to MDD and SDD. Genetic effects associated with common genome-wide genetic variants (SNP heritability) and additional pedigree-associated genetic variation and Non-genetic effects associated with common environments were estimated using linear mixed modeling (LMM).FindingsBoth MDD and SDD had significant contributions from effects of common genetic variants, the additional genetic effect of the pedigree and the common environmental effect shared by couples. The correlation between SDD and MDD was high (r=1⋅00, se=0⋅21) for common-variant-associated genetic effects and moderate for both the additional genetic effect of the pedigree (r=0⋅58, se=0⋅08) and the couple-shared environmental effect (r=0⋅53, se=0⋅22).InterpretationBoth genetics and couple-shared environmental effects were the major factors influencing liability to depression. SDD may provide a scalable alternative to MDD in studies seeking to identify common risk variants. Rarer variants and environmental effects may however differ substantially according to different definitions of depression.FundingStudy supported by Wellcome Trust Strategic Award 104036/Z/14/Z. GS:SFHS funded by the Scottish Government Health Department, Chief Scientist Office, number CZD/16/6.

Partitioning plant genetic and environmental drivers of above and belowground community assembly

2017 ◽  
Author(s):  
Matthew Barbour ◽  
Sonya Erlandson ◽  
Kabir Peay ◽  
Brendan Locke ◽  
Erik S. Jules ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Phenotypic Plasticity ◽  
Host Plant ◽  
Environmental Effects ◽  
Natural Variation ◽  
Plant Traits ◽  
Genetic Effects ◽  
Environmental Drivers ◽  
Leaf Quality ◽  
Wind Exposure

Host-plant genetic variation affects the diversity and composition of associated above and belowground communities. Most evidence supporting this view is derived from studies within a single common garden, thereby constraining the range of biotic and abiotic environmental conditions that might directly or indirectly (via phenotypic plasticity) affect communities. If natural variability in the environment renders host-plant genetic effects on associated communities unimportant, then studying the community-level consequences of genetic variation may not be warranted. We addressed this knowledge gap by planting a series of common gardens consisting of 10 different clones (genotypes) of the willow Salix hookeriana in a coastal dune ecosystem and manipulated natural variation in ant-aphid interactions (biotic) and wind exposure (abiotic) in two separate experiments. We then quantified the responses of associated species assemblages both above (foliar arthropods) and belowground (rhizosphere fungi and bacteria). In addition, we quantified plant phenotypic responses (plant growth, leaf quality, and root quality) to tease apart the effects of genetic variation, phenotypic plasticity, and direct environmental effects on associated communities. In the ant-aphid experiment, we found that willow genotype explained more variation in foliar arthropod communities than aphid additions and proximity to aphid-tending ant mounds. However, aphid additions modified willow genetic effects on arthropod community composition by attracting other aphid species to certain willow genotypes. In the wind experiment, wind exposure explained more variation than willow genotype in structuring communities of foliar arthropods and rhizosphere bacteria. Still, willow genotype had strong effect sizes on several community properties of arthropods and fungi, indicating that host-plant genetic variation remains important. Across both experiments, genetic variation in plant traits was more important than phenotypic plasticity in structuring associated communities. The relative importance of genetic variation vs. direct environmental effects though depended on the type of environmental gradient (G > E-aphid, but E-wind > G). Taken together, our results suggest that host-plant genetic variation is an important driver of above and belowground biodiversity, despite natural variation in the biotic and abiotic environment.

565. A study of variation in twin cattle: III. Growth

1955 ◽  
Vol 22 (1) ◽  
pp. 1-9 ◽  
Author(s):  
J. W. B. King ◽  
H. P. Donald
Keyword(s):  
Environmental Effects ◽  
Live Weight ◽  
Genetic Effects ◽  
Point Of View ◽  
Environmental Variance ◽  
Simple Assumption ◽  
Polynomial Coefficients ◽  
Straight Line ◽  
Best Fitting ◽  
Additive Genetic Effects

1. Polynomial coefficients have been fitted to data on growth in live weight to 19 months and on height at withers to 27 months of age shown by one-egg (MZ) and two-egg (DZ) twins and pairs of half-sisters (HZ). The coefficients obtained (a0, a2 and a3) have been subjected to analysis of variance.2. For growth in live weight, the ratio of intrapair variances for MZ, DZ and HZ pairs was 1:6·8:10 for a1, which gives the straight line best fitting the observed curve. Unrelated pairs, it is calculated, would have had an intrapair variance 20·9 times as great as MZ pairs. From the point of view of minimizing the intrapair variance, the advantage of the MZ pairs was usually a little less for a0, and considerably less for a2 and a3.3. For height at withers, the results were similar to those for weight.4. The contribution of environmental variance to total intrapair variance increased from a0 to a3, while that due to additive genetic effects diminished. Owing to the wide fiducial limits applicable, the results can be accommodated assuming only additive genetic effects in addition to environmental effects as estimated from one-egg twins. The extent to which HZ pairs exceeded the variance expected, however, suggests that this simple assumption may prove inadequate.

scholarly journals Genetic analysis of milk yield, fat and protein content in Holstein dairy cows in Iran: Legendre

2013 ◽  
Vol 56 (1) ◽  
pp. 497-508
Author(s):  
R. Abdullahpour ◽  
M. M. Shahrbabak ◽  
A. Nejati-Javaremi ◽  
R. V. Torshizi ◽  
R. Mrode
Keyword(s):  
Protein Content ◽  
Milk Yield ◽  
Environmental Effects ◽  
Milk Fat ◽  
Legendre Polynomials ◽  
Fat Content ◽  
Genetic Effects ◽  
Residual Variance ◽  
Genetic Trend ◽  
Additive Genetic Effects

Abstract. Data including 219 105 test day records of 22 569 first parity Holstein cows in 56 herds were analysed for milk yield, fat content and protein content. Legendre polynomials were used in a random regression model to explain traits curves, additive genetic and permanent environmental effects along days in milk (DIM). Legendre polynomials of order 3 were used to describe additive genetic effects on the traits. For permanent environmental effects, for milk the order of 6 and for fat and protein content the order of 4 were used. Heterogeneity of residual variance was considered. Restricted maximum likelihood (REML) methodology was used to estimate the required parameters. Variations in genetic, permanent environment and residual effects and heritability changes along DIM were computed and illustrated. Daily heritability estimates averaged as 0.22, 0.14 and 0.23 for milk, fat and protein contents, respectively. Minimum correlations between DIM for additive genetic effects were as 0.49, −0.01 and 0.34 for milk, fat and protein contents. There were higher genetic correlations between test day milk yield and protein content compared to fat content. The genetic trend of milk yield has increased over the years from 1971 to 2005, while the genetic trend for fat and protein content declined.

scholarly journals Determination of the best model for estimating heritability of economic traits and their genetic and phenotypic trends in Iranian native fowl

2013 ◽  
Vol 56 (1) ◽  
pp. 237-245
Author(s):  
M. Salehinasab ◽  
S. Zerehdaran ◽  
M. A. Abbasi ◽  
S. Alijani ◽  
S. Hassani
Keyword(s):  
Maternal Effects ◽  
Environmental Effects ◽  
Sexual Maturity ◽  
Information Criterion ◽  
Genetic Effects ◽  
Likelihood Method ◽  
Economic Traits ◽  
Egg Weight ◽  
Basic Model ◽  
Egg Number

Abstract. The objective of the present study was to estimate the heritability and to assess the existence of maternal effects for economic traits in Iranian native fowl. Variance components were estimated for body weight at hatch (BW0), 8 (BW8) and 12 (BW12) weeks of age, age at sexual maturity and weight at sexual maturity, egg number and average egg weight at 28th, 30th and 32nd weeks using restricted maximum likelihood method and six animal models. The best model was determined using the Akaike information criterion for each trait. For age at sexual maturity, the basic model consisting of direct genetic effects was superior. For weight at sexual maturity and egg number, a model consisting of maternal permanent environmental effects in addition to direct genetic effects was the best. For average egg weight at 28th, 30th and 32nd weeks, the model with direct and maternal genetic effects assuming no covariance between them was the best. For BW0, BW8 and BW12, the model including maternal genetic and permanent environmental effects in addition to direct genetic effects was the most appropriate. The estimates of direct heritability ranged from 0.05 (BW0) to 0.35 (weight at sexual maturity). Direct genetic variance and heritability were overestimated if maternal effects were ignored in the statistical model for all traits except ASM. The results indicated that the evaluation of direct and maternal genetic and phenotypic trends based on the best model for each trait was carried out. Maternal genetic trends for BW0, BW8, BW12 and average egg weight at 28th, 30th and 32nd weeks were significantly positive. Present results indicated favourable effects of the performed breeding program for all traits except BW0, during generations.

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