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Genetic Influences (genetic + influence)
Kinds of Genetic Influences Selected AbstractsGENETIC INFLUENCES ON THE ARTERIAL WALLCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 7 2007Bronwyn Kingwell SUMMARY 1Arterial stiffness, which has independent predictive value for cardiovascular events, seems to have a genetic component, largely independent of the influence of blood pressure and other cardiovascular risk factors. 2In animal models of essential hypertension (stroke-prone spontaneously hypertensive rats and spontaneously hypertensive rats), structural modifications of the arterial wall include an increase in the number of elastin,smooth muscle cell connections and smaller fenestrations of the internal elastic lamina, possibility leading to redistribution of the mechanical load towards elastic materials. These modifications may give rise to mechanisms explaining why changes in arterial wall material accompanying wall hypertrophy in these animals are not associated with an increase in arterial stiffness. 3In monogenic connective tissue diseases (Marfan, Williams and Ehlers,Danlos syndromes) and the corresponding animal models, precise characterization of the arterial phenotype makes it possible to determine the influence of abnormal, genetically determined, wall components on arterial stiffness. 4Such studies have highlighted the role of extracellular matrix signalling in the vascular wall and have shown that elastin and collagen not only display elasticity or rigidity, but are also involved in the control of smooth muscle cell function. 5These data provide strong evidence that arterial stiffness is affected by the amount and density of stiff wall material and the spatial organization of that material. [source] Not by Twins Alone: Using the Extended Family Design to Investigate Genetic Influence on Political BeliefsAMERICAN JOURNAL OF POLITICAL SCIENCE, Issue 3 2010Peter K. Hatemi Variance components estimates of political and social attitudes suggest a substantial level of genetic influence, but the results have been challenged because they rely on data from twins only. In this analysis, we include responses from parents and nontwin full siblings of twins, account for measurement error by using a panel design, and estimate genetic and environmental variance by maximum-likelihood structural equation modeling. By doing so, we address the central concerns of critics, including that the twin-only design offers no verification of either the equal environments or random mating assumptions. Moving beyond the twin-only design leads to the conclusion that for most political and social attitudes, genetic influences account for an even greater proportion of individual differences than reported by studies using more limited data and more elementary estimation techniques. These findings make it increasingly difficult to deny that,however indirectly,genetics plays a role in the formation of political and social attitudes. [source] The Limits of Genetic Influence: A Behavior-Genetic Analysis of Infant,Caregiver Relationship Quality and TemperamentCHILD DEVELOPMENT, Issue 6 2006Glenn I. Roisman This report presents data on 9-month-old twin pairs (nMZ=172; nDZ=333) from the Early Childhood Longitudinal Study, demonstrating that the role of genetic variation among infants is trivial and the shared and nonshared environment is substantial in accounting for the observed quality of infant,caregiver relationships. In contrast, maternal reports of temperament were best accounted for by genetic variation and nonshared environmental influences. Interestingly, however, shared environmental effects were documented for observations of temperament. Consistent with a growing database, the current study calls into question the ubiquity of heritability effects in all domains of psychological inquiry. It also bolsters consensus in the field of developmental psychology that shared environmental effects are not as elusive as had once been thought. [source] Neuroticism and Morning Cortisol Secretion: Both Heritable, But No Shared Genetic InfluencesJOURNAL OF PERSONALITY, Issue 5 2009Harriėtte Riese ABSTRACT Neuroticism is widely used as an explanatory concept in etiological research of psychopathology. To clarify what neuroticism actually represents, we investigated the phenotypic and genetic relationship between neuroticism and the morning cortisol secretion. In the current classic twin study, 125 female twin pairs (74 monozygotic and 51 dizygotic pairs) participated. For each participant, 4 different neuroticism scores were available to calculate a neuroticism composite score that was used in the statistical analyses. The morning cortisol secretion was assessed by 4 salivary samples in the 1st hour after awakening. Significant genetic influences for the neuroticism composite score (55%), and each of the 4 cortisol samples (52%,69%) were found. There was no phenotypic or genotypic relationship between neuroticism and morning cortisol secretion. Although neuroticism and cortisol were both heritable traits, they did not share any genetic influences. [source] The Relationship Between Genetic Influences on Alcohol Dependence and on Patterns of Alcohol ConsumptionALCOHOLISM, Issue 6 2010Kenneth S. Kendler Background:, Genetic factors impact substantially both on alcohol consumption (AC) and on the risk for alcohol dependence (AD). However, we know little about the degree to which measures of AC index the genetic risk for AD. Methods:, We assessed a lifetime history of AD by DSM-IV criteria and four measures of AC at the time of heaviest drinking (drink frequency, regular quantity, maximum quantity, and drunk frequency) in 5,073 adult twins from same-sex pairs from the Virginia Twin Registry. Structural models were fitted using Mx. Results:, We found evidence for different genetic structure in the sexes. In women, genetic risk for AD and for the four measures of AC was entirely shared. In men, the AC measures captured 85% of the genetic risk for AD. In women, the genetic relationship with AD was strongest for drunk frequency and in men for both drunk frequency and regular quantity. Conclusions:, In a population-based sample of twins, four relatively simple measures of AC obtained for the time of lifetime heaviest drinking were able to capture all (in women) or a very large proportion (in men) of the genetic risk for the complex multi-dimensional construct of AD. If replicated, these results have practical implications for studies aiming to assess genetic risk for AD. [source] Evidence for an Interaction Between Age at First Drink and Genetic Influences on DSM-IV Alcohol Dependence SymptomsALCOHOLISM, Issue 12 2009Arpana Agrawal Background:, Research suggests that individuals who start drinking at an early age are more likely to subsequently develop alcohol dependence. Twin studies have demonstrated that the liability to age at first drink and to alcohol dependence are influenced by common genetic and environmental factors, however, age at first drink may also environmentally mediate increased risk for alcohol dependence. In this study, we examine whether age at first drink moderates genetic and environmental influences, via gene × environment interactions, on DSM-IV alcohol dependence symptoms. Methods:, Using data on 6,257 adult monozygotic and dizygotic male and female twins from Australia, we examined the extent to which age at first drink (i) increased mean alcohol dependence symptoms and (ii) whether the magnitude of additive genetic, shared, and nonshared environmental influences on alcohol dependence symptoms varied as a function of decreasing age. Twin models were fitted in Mx. Results:, Risk for alcohol dependence symptoms increased with decreasing age at first drink. Heritable influences on alcohol dependence symptoms were considerably larger in those who reported an age at first drink prior to 13 years of age. In those with later onset of alcohol use, variance in alcohol dependence was largely attributable to nonshared environmental variance (and measurement error). This evidence for unmeasured gene × measured environment interaction persisted even when controlling for the genetic influences that overlapped between age at first drink and alcohol dependence symptoms. Conclusions:, Early age at first drink may facilitate the expression of genes associated with vulnerability to alcohol dependence symptoms. This is important to consider, not only from a public health standpoint, but also in future genomic studies of alcohol dependence. [source] The Role of Socioregional Factors in Moderating Genetic Influences on Early Adolescent Behavior Problems and Alcohol UseALCOHOLISM, Issue 10 2009Danielle M. Dick Background:, Twin and family studies have demonstrated that adolescent alcohol use and behavior problems are influenced by a combination of genetic and environmental factors. More recently, studies have begun to investigate how genetic and environmental influences may interact, with efforts underway to identify specific environmental variables that moderate the expression of genetic predispositions. Previously, we have reported that community-level factors, including urban/rural residency, migration rates, and prevalence of young adults, moderate the importance of genetic effects on alcohol use in late adolescence (ages 16 to 18). Here, we extend these findings to test for moderating effects of these socioregional factors on alcohol use and behavior problems assessed in a younger sample of adolescent Finnish twins. Methods:, Using data from the population-based Finnish twin study, FinnTwin12, biometric twin models were fit to data on >1,400 twin pairs to examine the significance of each of the socioregional moderating variables on alcohol use measured at age 14, and behavior problems, measured at age 12. Results:, We find no evidence of a moderating role of these socioregional variables on alcohol use; however, there was significant moderation of genetic influences on behavior problems, with effects limited to girls. Genetic influences assumed greater importance in urban settings, communities with greater migration, and communities with a higher percentage of slightly older adolescents. Conclusions:, The moderation effects observed on behavior problems in early adolescence paralleled the effects found on alcohol use late in adolescence in an independent sample, providing further support for the idea that behavior problems may represent an earlier manifestation of the predisposition to subsequent alcohol problems. Our findings also support the growing body of evidence suggesting that females may be more susceptible to a variety of environmental influences than males. [source] Electrocardiographic Indices of Left Ventricular Hypertrophy and Repolarization Phase Share the Same Genetic Influences: A Twin StudyANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 4 2009Sara Mutikainen M.Sc. Background: Both left ventricular hypertrophy (LVH) and repolarization phase (RP) are known to be attributable to genetic influences, but less is known whether they share same genetic influences. The aim of this study was to investigate to what extent individual differences in electrocardiographic (ECG) LVH and RP are explained by genetic and environmental influences and whether these influences are shared between these two traits. Methods: Resting ECG recordings were obtained from 186 monozygotic and 203 dizygotic female twin individuals, aged 63 to 76 years. Latent factors, called LVH and RP, were formed to condense the information obtained from LVH indices (Cornell voltage and Cornell product) and T-wave amplitudes (leads V5 and II), respectively. Multivariate quantitative genetic modeling was used both to decompose the phenotypic variances into additive genetic, common environmental, and unique environmental influences, and for the calculation of genetic and environmental correlations between LVH and RP. Results: Additive genetic influences explained 16% of individual differences in LVH and 74% in RP. The remaining individual differences were explained by both common and unique environmental influences. The genetic correlation and unique environmental correlation between LVH and RP were ,0.93 and ,0.05, respectively. Conclusions: In older women without overt cardiac diseases, RP is under stronger genetic control than LVH. The majority of genetic influences are shared between LVH and RP whereas environmental influences are mainly specific to each. [source] Genetic Influences on Resting Electrocardiographic Variables in Older Women: A Twin StudyANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2009Sara Mutikainen M.Sc. Background: Previous studies in young and middle-aged men and women have shown that resting electrocardiographic (ECG) variables are influenced by genetic factors. However, the extent to which resting ECG variables are influenced by genetic factors in older women is unknown. Thus, the aim of this study was to estimate the relative contribution of genetic and environmental influences to individual differences in resting ECG variables among older female twins without overt cardiac diseases. Methods: Resting ECG recordings were obtained from 186 monozygotic and 203 dizygotic twin individuals, aged 63,76 years. Quantitative genetic modeling was used to decompose the phenotypic variance in each resting ECG variable into additive genetic, dominance genetic, shared environmental, and unique environmental influences. Results: The results showed that individual differences in the majority of the resting ECG variables were moderately to highly explained by additive genetic influences, ranging from 32% for T axis to 72% for TV5. The results also suggested dominance genetic influences on QRS duration, TV1, and Sokolow,Lyon voltage (36%, 53%, and 57%, respectively). Unique environmental influences were important for each resting ECG variable, whereas shared environmental influences were detected only for QT interval and QTc. Conclusion: In older women without overt cardiac diseases, genetic influences explain a moderate to high proportion of individual differences in the majority of the resting ECG variables. Genetic influences are especially strong for T-wave amplitudes, left ventricular mass, and hypertrophy indices, whereas other variables, including heart rate, intervals, and axes, are more affected by environmental influences. [source] On Thinking Clearly About Taxometrics, Schizotypy, and Genetic Influences: Correction to Widiger (2001)CLINICAL PSYCHOLOGY: SCIENCE AND PRACTICE, Issue 3 2003Mark F. LenzenwegerArticle first published online: 11 MAY 200 In a recent commentary on taxometric methods (Meehl, 1973; Waller & Meehl, 1998), Widiger (2001) takes issue with the value of the taxometric approach and offers his views on the use of taxometric methods and the interpretation of taxometric findings. A principal concern of Widiger's is what he terms the "exaggerated implications" (p. 529) that he believes have been offered by investigators who have interpreted taxometric findings. He misrepresents the findings and conclusions of a well-known taxometric study of schizotypy (Lenzenweger & Korfine, 1992) in order to substantiate the claim of "exaggerated implications" and ascribes to the authors of the original study a conclusion not drawn by them. The possible nature of a critical logical error in Widiger's assessment of the Lenzenweger and Korfine study is explored with special reference to the theoretical context of the original schizotypy study. [source] The Effect of Angiotensin II Type-1 Receptor Gene Polymorphisms on Doppler Blood Flow Parameters of Carotid and Brachial Arteries in Patients with Myocardial InfarctionECHOCARDIOGRAPHY, Issue 7 2006Onder Ozturk M.D. Background: Genetic influence on Doppler blood flow parameters of carotid and brachial arteries (BA) is uncertain. We investigated the relationship between the angiotensin II type-1 receptor (AT1R) gene polymorphism and the blood flow characteristics of common carotid arteries (CCA) and BA by color Doppler ultrasound (CDUS) in patients with a first anterior acute myocardial infarction (AMI). Methods and Results: Sixty-seven patients (15 women and 52 men), aged 25,77 years, with anterior AMI were studied. The AT1R genotypes were established. Based on the polymorphism of the AT1R, they were classified into three groups: AT1R AA genotype (Group1, n = 42 patients), AT1R AC genotype (Group 2, n = 17 patients), and AT1R CC genotype (Group 3, n = 8 patients). Peak-systolic velocity (PSV) and end-diastolic velocity (EDV) of right and left CCA, PSV of right BA, and intimal-medial thickness (IMT) of both CCA were measured by CDUS. All results evaluated statistically. The AT1R genotypes were distributed as follows: 63% AA, 25% AC, and 12% CC. PSV of BA and both CCA were higher in patients with CC and AC than AA (P < 0.05). Also, IMT of both CCA were also higher in the same groups (P < 0.05). Conclusions: Our results suggest that AT1R gene polymorphism influences Doppler blood flow parameters of both BA and CCA, and IMT of CCA. Although further studies are required. [source] Genetic influence in antithrombotic actions of atorvastatin in hypercholesterolaemiaEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 1 2008L. Puccetti ABSTRACT Background, Recent data indicate that statins could offer coronary artery disease (CAD) benefit even by mechanisms beyond lipid lowering. Genetic influence has been shown for some antithrombotic actions of statins via oxidized-low-density lipoprotein cholesterol (ox-LDL) receptors and nitric oxide synthase (NOS) activity modulation. The present study was designed to evaluate the influence of ox-LDL lectin-like receptor-1 (LOX-1) and NOS polymorphisms in the incidence of cardiovascular events in pure hypercholesterolaemic subjects during statin treatment. Materials and methods, A prospective 4-year study involving 1039 event-free subjects (643 males, 396 females) treated with atorvastatin (10,40 mg day,1) to reach the appropriate Adult Treatment Panel-III LDL target of 3·36 mmol L,1. Enrolled subjects were evaluated every 6 months or at a clinical event. LOX-1 3,UTR/T-C and NOS G894T polymorphisms were detected by allelic discrimination assays (polymerase chain reaction), lipid profile by enzymatic-colorimetric method, ox-LDL by enzyme linked immunosorbent assay, platelet activation by P-selectin (P-sel) expression (FACScan), NOS activity (by intracellular citrullin recovery) and homocysteine (high performance liquid chromatography), C-reactive protein (CRP) by sensitive nephelometric technique. Results, LOX-1 3,UTR/T showed the strongest association with events in the whole cohort with respect to each other variable including LDL reduction and NOS G894T (OR 4·90, 95% CI 3·19,6·98, P < 0·00001). Smoking influenced events in LDL-targeted subjects (P < 0·0001). Ox-LDL and P-sel were better indicators than LDL or other variables according to 3,UTR/C genotype regardless of the magnitude of LDL reduction (OR 4·21, 95% CI 2·29,6·70 P < 0·0001). Conclusions, LOX-1 polymorphisms could influence statin effectiveness in CAD prevention by induction of sensitivity to antithrombotic mechanisms such as antiplatelet activity. [source] The Relation between Observational Measures of Social Problem Solving and Familial Antisocial Behavior: Genetic and Environmental InfluencesJOURNAL OF RESEARCH ON ADOLESCENCE, Issue 4 2001Erica L. Spotts Deficits in social problem-solving skills are often associated with antisocial behavior, particularly in children's extrafamilial relationships. The current study was designed to examine this association in several new ways: the association was examined at two times in an adolescent sample within the context of the family; genetic models were used to estimate genetic and environmental effects on observational measures of problem solving and antisocial behavior and on the association between the two. The analyses were conducted as part of the Nonshared Environment in Adolescent Development project, consisting of 720 families at Time 1 (mean adolescent age: 14.5 years) and 440 families at Time 2 (mean adolescent age: 16.1 years). Genetic influence was found for antisocial behavior, but not for problem solving. The findings of shared environmental influences on these measures and their association are unusual in the behavioral genetic literature and are important in that respect. [source] Genetic influences on reading difficulties in boys and girls: the Colorado twin studyDYSLEXIA, Issue 1 2006Jesse L. Hawke Abstract To test the hypothesis that the genetic etiology for reading disability may differ in males and females, data from identical and fraternal twin pairs were analysed using both concordance and multiple regression methods. The sample included 264 identical (129 male, 135 female) and 214 same-sex fraternal (121 male, 93 female) twin pairs in which at least one member of each pair had reading difficulties. The difference between the identical and fraternal twin pair concordance rates was slightly larger for females than for males, suggesting a possible sex difference in etiology; however, a loglinear analysis of the three-way interaction of sex, zygosity, and concordance was not significant (p,0.17). The estimate of group heritability (hg2), a standardized measure of the extent to which reading difficulties are due to genetic influences, was somewhat greater for females than males (0.65 vs 0.54), but this difference was also not significant (p,0.35). Gender differences in hg2 were larger for younger children (less than 11.5 years of age) than for older children. However, the three-way interaction of sex, zygosity, and age was not significant when age was treated either categorically (p,0.86) or continuously (p,0.71). Thus, results of this study provide little or no evidence for a differential genetic etiology of reading difficulties in males and females. Copyright © 2005 John Wiley & Sons, Ltd. [source] The evolutionary genetics of personality,EUROPEAN JOURNAL OF PERSONALITY, Issue 5 2007Lars Penke Abstract Genetic influences on personality differences are ubiquitous, but their nature is not well understood. A theoretical framework might help, and can be provided by evolutionary genetics. We assess three evolutionary genetic mechanisms that could explain genetic variance in personality differences: selective neutrality, mutation-selection balance, and balancing selection. Based on evolutionary genetic theory and empirical results from behaviour genetics and personality psychology, we conclude that selective neutrality is largely irrelevant, that mutation-selection balance seems best at explaining genetic variance in intelligence, and that balancing selection by environmental heterogeneity seems best at explaining genetic variance in personality traits. We propose a general model of heritable personality differences that conceptualises intelligence as fitness components and personality traits as individual reaction norms of genotypes across environments, with different fitness consequences in different environmental niches. We also discuss the place of mental health in the model. This evolutionary genetic framework highlights the role of gene-environment interactions in the study of personality, yields new insight into the person-situation-debate and the structure of personality, and has practical implications for both quantitative and molecular genetic studies of personality. Copyright © 2007 John Wiley & Sons, Ltd. [source] Personality and marital satisfaction: a behavioural genetic analysisEUROPEAN JOURNAL OF PERSONALITY, Issue 3 2005Erica L. Spotts Previous research has found that genetic and nonshared environmental factors influence marital quality (Spotts et al., 2004). The current study explored personality as a source for these genetic and environmental individual differences. A sample of 752 Swedish twin women and their spouses were used. Genetic and environmental influences were found for self-report measures of marital quality, but only environmental factors contributed to the variance of observational measures of marital quality. Wives' personality characteristics accounted for genetic and nonshared environmental variance in the wives' own marital satisfaction, their husbands' marital satisfaction, and the agreement between the spouses on the quality of their marriage. Genetic influences on the correlation between wives' genetically influenced personality characteristics and their husbands' marital satisfaction indicate a gene,environment correlation. Contrary to expectations, husbands' personality did not explain large portions of wives' marital satisfaction beyond that explained by wives' personality. This study emphasizes the importance of spousal personality to the well-being of marriages, and results are discussed within the context of three different theories regarding associations between personality and marital quality. Copyright © 2005 John Wiley & Sons, Ltd. [source] Genetic Probes of Three Theories of Maternal Adjustment: II.FAMILY PROCESS, Issue 3 2001Environmental Influences, Genetic This is the first report of the Twin Mom Study, an investigation of three hypotheses concerning influences on maternal adjustment. These hypotheses concern the role of the marital and parent-child relationships in mediating genetic influences on maternal adjustment and on the importance of the mothers' marital partners as a specifiable source of influences on their adjustment not shared with their sisters. The study's sample of 150 monozygotic (MZ) twins and 176 dizygotic (DZ) twins was drawn randomly from the Swedish Twin Registry and is, with some small exceptions, likely to be representative of women in the Swedish population. The sample included the marital partners of these twins and their adolescent children. Self-report and coded videotapes were a source of information about family process. Results reported in this first report focus on comparability of American and Swedish samples on scales measuring psychiatric symptoms, and on an analysis of genetic and environmental influences on nine measures of mothers' adjustment. Results suggest comparability between the US and Sweden. Genetic influences were found for all measures of adjustment, particularly in the psychological manifestations of anxiety and for smoking. The pattern of findings also underscored the importance of influences unique to each sibling within the twin pair, thus focusing attention on the potential role of marital partners in maternal adjustment. Results also suggested that experiences shared by the twin sisters, experiences unrelated to their genetic similarity, may influence their fearfulness and alcohol consumption. Our model did not include these influences and thus must be amended. [source] Replication study of candidate genes for cognitive abilities: the Lothian Birth Cohort 1936GENES, BRAIN AND BEHAVIOR, Issue 2 2009L. M. Houlihan As the proportion of older people in societies has increased, research into the determinants of cognitive ageing has risen in importance. Genetic influences account for over 50% of the variance in adult cognitive abilities. Previous studies on cognition and illnesses with cognitive impairments have identified single nucleotide polymorphisms (SNPs) within candidate genes that might influence cognition or age-related cognitive change. This study investigated 10 candidate genes in over 1000 Scots: the Lothian Birth Cohort 1936 (LBC1936). These participants were tested on general cognitive ability (Scottish Mental Survey 1947) at age 11. At mean age 70, they completed the same general cognitive ability test and a battery of diverse cognitive tests. Nineteen SNPs in 10 genes previously associated with cognition, Alzheimer's disease or autism were genotyped in 1063 individuals. The genes include BDNF, COMT, DISC1, KL, NCSTN, PPP1R1B, PRNP, SHANK3, SORL1 and WRN. Linear regression analysis investigated the additive effect of each SNP on the cognitive variables, covarying for gender and age. Childhood cognitive ability was also included as a covariate to identify associations specifically with cognitive ageing. Certain SNPs reached the conventional significance threshold for association with cognitive traits or cognitive ageing in LBC1936 (P < 0.05). No SNPs reached the Bonferroni-level of significance (all P > 0.0015). Of the 10 genes, we discuss that COMT, KL, PRNP, PPP1R1B, SORL1 and WRN especially merit further attention for association with cognitive ability and/or age-related cognitive change. All results are also presented so that they are valuable for future meta-analyses of candidate genes for cognition. [source] Genetic influences on behavioral inhibition and anxiety in juvenile rhesus macaquesGENES, BRAIN AND BEHAVIOR, Issue 4 2008J. Rogers In humans and other animals, behavioral responses to threatening stimuli are an important component of temperament. Among children, extreme behavioral inhibition elicited by novel situations or strangers predicts the subsequent development of anxiety disorders and depression. Genetic differences among children are known to affect risk of developing behavioral inhibition and anxiety, but a more detailed understanding of genetic influences on susceptibility is needed. Nonhuman primates provide valuable models for studying the mechanisms underlying human behavior. Individual differences in threat-induced behavioral inhibition (freezing behavior) in young rhesus monkeys are stable over time and reflect individual levels of anxiety. This study used the well-established human intruder paradigm to elicit threat-induced freezing behavior and other behavioral responses in 285 young pedigreed rhesus monkeys. We examined the overall influence of quantitative genetic variation and tested the specific effect of the serotonin transporter promoter repeat polymorphism. Quantitative genetic analyses indicated that the residual heritability of freezing duration (behavioral inhibition) is h2 = 0.384 (P = 0.012) and of ,orienting to the intruder' (vigilance) is h2 = 0.908 (P = 0.00001). Duration of locomotion and hostility and frequency of cooing were not significantly heritable. The serotonin transporter polymorphism showed no significant effect on either freezing or orienting to the intruder. Our results suggest that this species could be used for detailed studies of genetic mechanisms influencing extreme behavioral inhibition, including the identification of specific genes that are involved in predisposing individuals to such behavior. [source] Genetic influences on human brain structure: A review of brain imaging studies in twins,HUMAN BRAIN MAPPING, Issue 6 2007Jiska S. Peper Abstract Twin studies suggest that variation in human brain volume is genetically influenced. The genes involved in human brain volume variation are still largely unknown, but several candidate genes have been suggested. An overview of structural Magnetic Resonance (brain) Imaging studies in twins is presented, which focuses on the influence of genetic factors on variation in healthy human brain volume. Twin studies have shown that genetic effects varied regionally within the brain, with high heritabilities of frontal lobe volumes (90,95%), moderate estimates in the hippocampus (40,69%), and environmental factors influencing several medial brain areas. High heritability estimates of brain structures were revealed for regional amounts of gray matter (density) in medial frontal cortex, Heschl's gyrus, and postcentral gyrus. In addition, moderate to high heritabilities for densities of Broca's area, anterior cingulate, hippocampus, amygdala, gray matter of the parahippocampal gyrus, and white matter of the superior occipitofrontal fasciculus were reported. The high heritability for (global) brain volumes, including the intracranium, total brain, cerebral gray, and white matter, seems to be present throughout life. Estimates of genetic and environmental influences on age-related changes in brain structure in children and adults await further longitudinal twin-studies. For prefrontal cortex volume, white matter, and hippocampus volumes, a number of candidate genes have been identified, whereas for other brain areas, only a few or even a single candidate gene has been found so far. New techniques such as genome-wide scans may become helpful in the search for genes that are involved in the regulation of human brain volume throughout life. Hum Brain Mapp, 2007. © 2007 Wiley-Liss, Inc. [source] The Role of Socioregional Factors in Moderating Genetic Influences on Early Adolescent Behavior Problems and Alcohol UseALCOHOLISM, Issue 10 2009Danielle M. Dick Background:, Twin and family studies have demonstrated that adolescent alcohol use and behavior problems are influenced by a combination of genetic and environmental factors. More recently, studies have begun to investigate how genetic and environmental influences may interact, with efforts underway to identify specific environmental variables that moderate the expression of genetic predispositions. Previously, we have reported that community-level factors, including urban/rural residency, migration rates, and prevalence of young adults, moderate the importance of genetic effects on alcohol use in late adolescence (ages 16 to 18). Here, we extend these findings to test for moderating effects of these socioregional factors on alcohol use and behavior problems assessed in a younger sample of adolescent Finnish twins. Methods:, Using data from the population-based Finnish twin study, FinnTwin12, biometric twin models were fit to data on >1,400 twin pairs to examine the significance of each of the socioregional moderating variables on alcohol use measured at age 14, and behavior problems, measured at age 12. Results:, We find no evidence of a moderating role of these socioregional variables on alcohol use; however, there was significant moderation of genetic influences on behavior problems, with effects limited to girls. Genetic influences assumed greater importance in urban settings, communities with greater migration, and communities with a higher percentage of slightly older adolescents. Conclusions:, The moderation effects observed on behavior problems in early adolescence paralleled the effects found on alcohol use late in adolescence in an independent sample, providing further support for the idea that behavior problems may represent an earlier manifestation of the predisposition to subsequent alcohol problems. Our findings also support the growing body of evidence suggesting that females may be more susceptible to a variety of environmental influences than males. [source] Genetic influences on heart rate variability at rest and during stressPSYCHOPHYSIOLOGY, Issue 3 2009Xiaoling Wang Abstract We tested whether the heritability of heart rate variability (HRV) under stress is different from rest and its dependency on ethnicity or gender. HRV indexed by root mean square of successive differences (RMSSD) and high-frequency (HF) power was measured at rest and during 3 stressors in 427 European and 308 African American twins. No ethnic or gender differences were found for any measures. There was a nonsignificant increase in heritability of RMSSD (from 0.48 to 0.58) and HF (from 0.50 to 0.58) under stress. Up to 81% and 60% of the heritabilities of RMSSD and HF under stress could be attributed to genes influencing rest levels. The heritabilities due to genes expressed under stress were 0.11 for RMSSD and 0.23 for HF. The findings suggest that, independent of ethnicity and gender, HRV regulation at rest and under stress is largely influenced by the same genes with a small but significant contribution of stress-specific genetic effects. [source] Dissecting the molecular architecture and origin of Bayash Romani patrilineages: Genetic influences from South-Asia and the BalkansAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009Irena Martinovi, Klari Abstract The Bayash are a branch of Romanian speaking Roma living dispersedly in Central, Eastern, and Southeastern Europe. To better understand the molecular architecture and origin of the Croatian Bayash paternal gene pool, 151 Bayash Y chromosomes were analyzed for 16 SNPs and 17 STRs and compared with European Romani and non-Romani majority populations from Europe, Turkey, and South Asia. Two main layers of Bayash paternal gene pool were identified: ancestral (Indian) and recent (European). The reduced diversity and expansion signals of H1a patrilineages imply descent from closely related paternal ancestors who could have settled in the Indian subcontinent, possibly as early as between the eighth and tenth centuries AD. The recent layer of the Bayash paternal pool is dominated by a specific subset of E1b1b1a lineages that are not found in the Balkan majority populations. At least two private mutational events occurred in the Bayash during their migrations from the southern Balkans toward Romania. Additional admixture, evident in the low frequencies of typical European haplogroups, J2, R1a, I1, R1b1b2, G, and I2a, took place primarily during the early Bayash settlement in the Balkans and the Romani bondage in Romania. Our results indicate two phenomena in the Bayash and analyzed Roma: a significant preservation of ancestral H1a haplotypes as a result of considerable, but variable level of endogamy and isolation and differential distribution of less frequent, but typical European lineages due to different patterns of the early demographic history in Europe marked by differential admixture and genetic drift. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] Genetic Influences on Resting Electrocardiographic Variables in Older Women: A Twin StudyANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2009Sara Mutikainen M.Sc. Background: Previous studies in young and middle-aged men and women have shown that resting electrocardiographic (ECG) variables are influenced by genetic factors. However, the extent to which resting ECG variables are influenced by genetic factors in older women is unknown. Thus, the aim of this study was to estimate the relative contribution of genetic and environmental influences to individual differences in resting ECG variables among older female twins without overt cardiac diseases. Methods: Resting ECG recordings were obtained from 186 monozygotic and 203 dizygotic twin individuals, aged 63,76 years. Quantitative genetic modeling was used to decompose the phenotypic variance in each resting ECG variable into additive genetic, dominance genetic, shared environmental, and unique environmental influences. Results: The results showed that individual differences in the majority of the resting ECG variables were moderately to highly explained by additive genetic influences, ranging from 32% for T axis to 72% for TV5. The results also suggested dominance genetic influences on QRS duration, TV1, and Sokolow,Lyon voltage (36%, 53%, and 57%, respectively). Unique environmental influences were important for each resting ECG variable, whereas shared environmental influences were detected only for QT interval and QTc. Conclusion: In older women without overt cardiac diseases, genetic influences explain a moderate to high proportion of individual differences in the majority of the resting ECG variables. Genetic influences are especially strong for T-wave amplitudes, left ventricular mass, and hypertrophy indices, whereas other variables, including heart rate, intervals, and axes, are more affected by environmental influences. [source] Fears and Phobias in Children: Phenomenology, Epidemiology, and AetiologyCHILD AND ADOLESCENT MENTAL HEALTH, Issue 3 2002Thomas H. Ollendick We examine the phenomenology, epidemiology, and aetiology of specific phobias in this brief review. In general terms, a specific phobia exists when fear of a specific object or situation is exaggerated, cannot be reasoned away, results in avoidance of the feared object or situation, persists over time, and is not age-specific. Specific phobias occur in about 5% of children and in approximately 15% of children referred for anxiety-related problems. Most of these children are comorbid with other disorders. We suggest that specific phobias are multiply determined and over-determined. Genetic influences, temperamental predispositions, parental psychopathology, parenting practices, and individual conditioning histories converge to occasion the development and maintenance of childhood phobias. Inasmuch as any one specific phobia is acquired and maintained through such complex processes, we further conclude that treatment approaches will need to address these multiple dimensions before evidence-based treatments can be fully realised. [source] Dyslexia: nature and nurture,DYSLEXIA, Issue 3 2002Richard K. Olson Abstract This paper explores the balance of genetic and environmental influences on dyslexia in generally supportive educational environments. Evidence from family studies suggests and research with identical and fraternal twins confirms the presence of strong genetic influences on dyslexia, though the way dyslexia is defined influences the degree of genetic influence. The behavioural genetic evidence is supported with molecular genetic evidence from DNA analyses suggesting regions on several different chromosomes where genes related to dyslexia are likely to be found. The behavioural and molecular genetic analyses are also applied to different component word reading skills (orthographic coding and phonological decoding) as well as to related language skills (phoneme awareness) to better understand the genetic and cognitive pathways to dyslexia. Copyright © 2002 John Wiley & Sons, Ltd. [source] Genetic Probes of Three Theories of Maternal Adjustment: I. Recent Evidence and a Model,FAMILY PROCESS, Issue 3 2001David Reiss M.D. Studies focusing on genetic and social influences on maternal adjustment will illumine mother's marriage, parenting, and the development of psychopathology in her children. Recent behavioral genetic research suggests mechanisms by which genetic and social influences determine psychological development and adjustment. First, heritable, personal attributes may influence individuals' relationships with their family members. These genetically influenced family patterns may amplify the effects of adverse, heritable personal attributes on adjustment. Second, influences unique to siblings may be the most important environmental determinants of adjustment. We derive three hypotheses on maternal adjustment from integrating these findings from genetic studies with other contemporary research on maternal adjustment. First, mother's marriage mediates the influence of her heritable, personal attributes on her adjustment. Second, mother's recall of how she was parented is partially genetically influenced, and both her relationships with her spouse and her child mediate the impact of these genetically influenced representations on her current adjustment. Third, characteristics of mother's spouse are important influences on difference between her adjustment and that of her sister's These sibling-specific influences are unrelated to mother's heritable attributes. The current article develops this model, and the companion article describes the Twin Mom Study that was designed to test it as well, as its first findings. Data from this study can illumine the role of family process in the expression of genetic influence and lead to specific family interventions designed to offset adverse genetic influences. [source] Sensitivity to the locomotor-stimulant effects of ethanol and allopregnanolone: a quantitative trait locus study of common genetic influenceGENES, BRAIN AND BEHAVIOR, Issue 7 2006A. A. Palmer Previous studies have suggested that common genetic mechanisms influence sensitivity to the locomotor-stimulant effects of ethanol and allopregnanolone. We conducted two quantitative trait locus (QTL) studies to identify chromosomal regions that harbor genes that influence locomotor response to ethanol (2 g/kg) and allopregnanolone (17 mg/kg) using F2 crosses between C57BL/6J and DBA/2J mice. Because our previous data from the BXD recombinant inbred strains had indicated that chromosome 2 contained QTL for sensitivity to the locomotor-stimulant effects of both ethanol and allopregnanolone, we also tested reciprocal chromosome 2 congenic strains for sensitivity to the locomotor-stimulant effects of both drugs. The F2 analysis for ethanol sensitivity identified significant QTL on chromosomes 1 and 2 and suggestive QTL on chromosomes 5 and 9. The analysis of the allopregnanolone F2 study identified suggestive QTL on chromosomes 3, 5 and 12. Suggestive evidence for a female-specific QTL on chromosome 2 was also found. The studies of congenic mouse strains indicated that both the congenic strains captured one or more QTL for sensitivity to the locomotor-stimulant effects of both ethanol (2 g/kg) and allopregnanolone (17 mg/kg). When Fisher's method was used to combine the P values for the RI, F2 and congenic studies of the chromosome 2 QTL, cumulative probability scores of 9.6 × 10,15 for ethanol and 7.7 × 10,7 for allopregnanolone were obtained. These results confirm the presence of QTL for ethanol and allopregnanolone sensitivity in a common region of chromosome 2 and suggest possible pleiotropic genetic influence on sensitivity to these drugs. [source] Fine mapping of a sedative-hypnotic drug withdrawal locus on mouse chromosome 11GENES, BRAIN AND BEHAVIOR, Issue 1 2006H. M. Hood We have established that there is a considerable amount of common genetic influence on physiological dependence and associated withdrawal from sedative-hypnotic drugs including alcohol, benzodiazepines, barbiturates and inhalants. We previously mapped two loci responsible for 12 and 9% of the genetic variance in acute alcohol and pentobarbital withdrawal convulsion liability in mice, respectively, to an approximately 28-cM interval of proximal chromosome 11. Here, we narrow the position of these two loci to a 3-cM interval (8.8 Mb, containing 34 known and predicted genes) using haplotype analysis. These include genes encoding four subunits of the GABAA receptor, which is implicated as a pivotal component in sedative-hypnotic dependence and withdrawal. We report that the DBA/2J mouse strain, which exhibits severe withdrawal from sedative-hypnotic drugs, encodes a unique GABAA receptor ,2 subunit variant compared with other standard inbred strains including the genetically similar DBA/1J strain. We also demonstrate that withdrawal from zolpidem, a benzodiazepine receptor agonist selective for ,1 subunit containing GABAA receptors, is influenced by a chromosome 11 locus, suggesting that the same locus (gene) influences risk of alcohol, benzodiazepine and barbiturate withdrawal. Our results, together with recent knockout studies, point to the GABAA receptor ,2 subunit gene (Gabrg2) as a promising candidate gene to underlie phenotypic differences in sedative-hypnotic physiological dependence and associated withdrawal episodes. [source] Impact of determination of hepatitis B virus subgenotype and pre-core/core-promoter mutation for the prediction of acute exacerbation of asymptomatic carriersHEPATOLOGY RESEARCH, Issue 4 2009Tadashi Ikegami Aim:, A large cohort study in Japan revealed that the specific viral profile may influence the fulminant outcome in acute hepatitis B virus (HBV) infections, while the genetic influence on outcome has not been clarified in patients with acute exacerbation of chronic liver disease caused by HBV. We experienced a case of fatal liver failure that developed as the result of chronic HBV infection. To determine possible genetic factor involving acute exacerbation, genetic analysis of serum from the patient and his siblings was performed. Methods:, HBV subgenotype as well as pre-core/core-promoter mutations of samples mentioned above were determined. Results:, Patient had HBV-Bj with pre-core (1896/1899) and core-promoter (1762/1764) mutations, the genomic profile frequently seen in fulminant hepatitis caused by acute HBV infection. Conclusion:, This result suggests that determination of the HBV subgenotype and pre-core/core promoter mutations could provide a rationale for development of a treatment strategy in asymptomatic HBV carriers. [source] | ||||||||||||||||||||||||||||||||||||||||