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Hemispheric asymmetry is a fundamental organizing principle of the human brain. Answering the genetic effects of the asymmetry is a prerequisite for elucidating developmental mechanisms of brain asymmetries. Multi-modal magnetic resonance imaging (MRI) has provided an important tool for comprehensively interpreting human brain asymmetry and its genetic mechanism. By combining MRI data, individual differences in brain structural asymmetry have been investigated with quantitative genetic brain mapping using gene-heritability. Twins provide a useful natural model for studying the effects of genetics and environment on the brain. Studies based on MRI have found that the asymmetry of human brain structure has a genetic basis. From the perspective of quantitative genetic analysis, this article reviews recent findings on the genetic effects of asymmetry and genetic covariance between hemispheres from three aspects: the asymmetry of heritability, the heritability of asymmetry and the genetic correlation. At last, the article shows the limitations and future research directions in this field. The purpose of this systematic review is to quickly guide researchers to understand the origins and genetic mechanism of interhemispheric differences, and provide a genetic basis for further understanding and exploring individual differences in laterized cognitive behavior.
Subject(s)
Humans , Brain/diagnostic imaging , Brain Mapping , Magnetic Resonance Imaging , Twins/geneticsABSTRACT
OBJECTIVE: The purpose of this study was to investigate the influence of heritability on the craniofacial soft tissue cephalometric characteristics of monozygotic (MZ) twins, dizygotic (DZ) twins, and their siblings (SIB). METHODS: The samples comprised Korean adult twins and their siblings (mean age, 39.8 years; MZ group, n = 36 pairs; DZ group, n = 13 pairs of the same gender; and SIB group, n = 26 pairs of the same gender). Thirty cephalometric variables were measured to characterize facial profile, facial height, soft-tissue thickness, and projection of nose and lip. Falconer's method was used to calculate heritability (low heritability, h2 0.9). After principal components analysis (PCA) was performed to extract the models, we calculated the intraclass correlation coefficient (ICC) value and heritability of each component. RESULTS: The MZ group exhibited higher ICC values for all cephalometric variables than DZ and SIB groups. Among cephalometric variables, the highest h2 (MZ-DZ) and h2 (MZ-SIB) values were observed for the nasolabial angle (NLA, 1.544 and 2.036), chin angle (1.342 and 1.112), soft tissue chin thickness (2.872 and 1.226), and upper lip thickness ratio (1.592 and 1.026). PCA derived eight components with 84.5% of a cumulative explanation. The components that exhibited higher values of h2 (MZ-DZ) and h2 (MZ-SIB) were PCA2, which includes facial convexity, NLA, and nose projection (1.026 and 0.972), and PCA7, which includes chin angle and soft tissue chin thickness (2.107 and 1.169). CONCLUSIONS: The nose and soft tissue chin were more influenced by genetic factors than other soft tissues.
Subject(s)
Adult , Humans , Chin , Lip , Methods , Nose , Passive Cutaneous Anaphylaxis , Siblings , Twins , Twins, Dizygotic , Twins, MonozygoticABSTRACT
Objective@#To analyze the heritability of diabetes among the Chinese twin adults.@*Methods@#A total of 10 253 same-sex twin pairs aged 25 years and older, were selected from the Chinese National Twin Registry (CNTR) program. Heritability of diabetes was calculated by using the structural equation model.@*Results@#After adjusted for age and gender, the overall heritability rates of diabetes were 0.41 (0.15-0.75), 0.83 (0.72-0.91) and 0.34 (0.04-0.73) in the <45 and ≥45 years twin pairs, respectively. After adjusted for age, rates of heritability appeared as 0.37 (0.05-0.78) and 0.88 (0.79-0.94) in men and women, respectively.@*Conclusions@#Diabetes is affected by both genetic and environmental factors. The genetic effect of diabetes seemed stronger on female than that on male twins but was dying down along with ageing.
ABSTRACT
The prevalence of child and adolescent growth and mental-behavior related diseases are increasing,and the pathogcnesis are complex.Twins are excellent natural resources for complex chronic diseases research as they share the maternal intrauterine environment,born at the same time and share the same family environment in early years,which could benefit the adjust ment of confounding factors,such as age,genetic factors and early family environmental factors.Birth cohort with twin families involved could be more effective in exploring the genetic and environmental factors for complex chronic diseases at the very beginning of life.This paper summarizes the objective,content,progress,strengths and potential problems of Wuhan Twin Birth Cohort,with emphasis on the overall design and progress of the study.
ABSTRACT
The prevalence of child and adolescent growth and mental-behavior related diseases are increasing,and the pathogcnesis are complex.Twins are excellent natural resources for complex chronic diseases research as they share the maternal intrauterine environment,born at the same time and share the same family environment in early years,which could benefit the adjust ment of confounding factors,such as age,genetic factors and early family environmental factors.Birth cohort with twin families involved could be more effective in exploring the genetic and environmental factors for complex chronic diseases at the very beginning of life.This paper summarizes the objective,content,progress,strengths and potential problems of Wuhan Twin Birth Cohort,with emphasis on the overall design and progress of the study.
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Objective To investigate the varying variances of the genetic components in birth cohorts.Methods Twin samples used in the current study were collected from the Chinese National Twin Registry and a two-wave study was conducted,in Qingdao and Lishui regions.Samples were broken down by birth cohort to create four subgroups:-1958,1959-1961,1962-1970 and 1970-.Structural equation models were fitted in each subgroup to estimate the genetic and environmental variances.Results From each birth cohort,weight and body mass index in 2012 appeared higher than those in 2001.Twins of 1971-cohort subgroup showed lower weight than in the other cohort subgroups.Except for the 1959-1961 cohort subgroup,the later birth cohorts were inversely related to the body mass indexes.Genetic factors might explain 54％-76％ of the total variations on the body mass index.Heritability of body mass index of twins born during 1959-1961 was increasing along with age.Conclusion Genetic factors might explain the main portion which related to the phenotypic variance of body mass index.Effects of genetic factors on body mass index of twins born during 1959-1961 might have increased along with age.
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The importance of large cohort studies in China has been increasingly emphasized.As special group in the population,twins provide excellent natural resources since they share the same birthday,maternal intrauterine environment and early family environment.Twin cohorts are unique for and benefit on controlling the confounding factors as age,gender (same-sex twins),genetic background (monozygotic twins) or early environment (being raised together) in the etiological studies on complex diseases.In this review,we briefly introduce the objectives,current situation,challenges and opportunities related to the Chinese national twin cohort,focusing on the characteristics of twins that are different from other groups in the general population.
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Objective:To explore the relations of adolescents'behavioral problems to genetic and environmental factors.Methods:66 twin pairs aged 12 to 18 years in Chongqing were included in the study.The Youth Self-Report (YSR) was used to evaluate behavioral problems.The blood sample was collected to identify zygosity of twins.Genetic effects were evaluated by comparing the phenotypic correlationamong monozygotic twins(rMZ) and the phenotypic correlation among dizygotic twins(rDZ).Structural equation modeling (SEM) was performed to evaluate the relations of adolescents behavioral problems to the additive genetic factors (A),shared environment factors (C) and individual specific environmental factors (E).Results:MZ correlations of Social problems and Delinquency were less than DZ correlations(rMZ ＜ rDZ).It prompted that data was not suitable for genetic analysis.MZ correlations(rMZ) of any others (including social withdrawal,somatic complaints,anxiety/depression,thinking problem,attention problems,self-destructive/identity problem)were less than 2DZ correlations (2rDZ).It prompted to fit the ACE model.The optimal model was AE model.Among the contribution of the additive genetic factors (A) and individual specific environmental factors (E)to the total variance,the genetic factors ranged from 0.52 to 0.57 and individual specific environmental factors ranged from 0.43 to 0.48 in anxiety/depression and self-destructive/identity problem.For social withdrawal,somatic complaints,thinking problem and attention problems,the genetic factors ranged from 0.17 to 0.45and individual specific environmental factors ranged from 0.55 to 0.83.Conclusion:There is no obvious relationship between genetic effects and adolescent social problems or delinquency.Other behaviors problems (social withdrawal,somatic complaints,anxiety/depression,thinking problem,attention problem,self-destructive/identity problem)are correlated with additive genetic factors and individual specific environmental factors.Additive genetic factors have high-correlation with anxiety/depression and self-destructive/identity problem,and individual specific environmental factors have high-correlation with other factors.
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Objective To explore the relationship of adolescents internalizing problem behavior with genetic and environmental factors. Methods The internalizing problem behavior of 74 twin pairs from Chongqing(aged from 12 to18 years) were investigated using The Youth Self-Report (YSR). The family adaptability and cohesion evaluationscale 2nd edition Chinese version (FACES Ⅱ-CV), Family Stresses Questionnaire (FSQ), the Parenting Styles and Dimensions Questionnaire (PSDQ), Stressful Life Event (SLE) and Simplified Coping Style Questionnaire (SCSQ ) were applied to assess their environment factors and coping style. The blood sample was collected to verify zygosity of twins. Structural equation modeling (SEM)was performed to evaluate the relationship of adolescents internalizing problem behavior with the additive genetic factors(A),shared environment factors(C)and individual specific environmental factors(E). Results The scores of PSDQ and FSQ FACES Ⅱ-CV SCSQ were no significantly different between homozygotic and dizygotic twins(P>0.05).There were significantly negative correlation between internalizing problem behavior and family cohesion (r=0.223, P=0.011).The scores of adolescent internalizing problem behavior were positively correlated with the scores of family stresses(r=0.232, P=0.008), the scores of Authoritarian-parenting-style(r=0.206, P=0.018), the scores of negative coping style (r=0.408, P=0.001);the scores of adolescents internalizing behavioral problems were not significantly correlated with the scores of the stress life events, and the scores of the parenting education level and occupation.The effects of A and E on adolescent internalizing problem behavior were 0.51(95%CI:0.27~0.69)and 0.49 (95% CI: 0.31~0.73) respectively. Conclusion Environmental factors and genetic factors contribute equally to adolescents internalizing problem behavior, which is affected by the authoritarian-parenting-style, family stresses, family cohesion and negative coping style.
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Objective To investigate the varying variances of the genetic components in birth cohorts.Methods Twin samples used in the current study were collected from the Chinese National Twin Registry and a two-wave study was conducted,in Qingdao and Lishui regions.Samples were broken down by birth cohort to create four subgroups:-1958,1959-1961,1962-1970 and 1970-.Structural equation models were fitted in each subgroup to estimate the genetic and environmental variances.Results From each birth cohort,weight and body mass index in 2012 appeared higher than those in 2001.Twins of 1971-cohort subgroup showed lower weight than in the other cohort subgroups.Except for the 1959-1961 cohort subgroup,the later birth cohorts were inversely related to the body mass indexes.Genetic factors might explain 54％-76％ of the total variations on the body mass index.Heritability of body mass index of twins born during 1959-1961 was increasing along with age.Conclusion Genetic factors might explain the main portion which related to the phenotypic variance of body mass index.Effects of genetic factors on body mass index of twins born during 1959-1961 might have increased along with age.
ABSTRACT
The importance of large cohort studies in China has been increasingly emphasized.As special group in the population,twins provide excellent natural resources since they share the same birthday,maternal intrauterine environment and early family environment.Twin cohorts are unique for and benefit on controlling the confounding factors as age,gender (same-sex twins),genetic background (monozygotic twins) or early environment (being raised together) in the etiological studies on complex diseases.In this review,we briefly introduce the objectives,current situation,challenges and opportunities related to the Chinese national twin cohort,focusing on the characteristics of twins that are different from other groups in the general population.
ABSTRACT
Research involving twins contributes much to the scientific world as they enable one to understand the complex morphological variations and the phenotypic expressions of various genes. Twin research study design illustrates and explains the relative contribution and interactions of genes and the environmental factors responsible for the development of a particular trait. Quantification of the genetic and environmental contributing factors enables researchers to explore the variations to various physical, behavioural disorders and dental diseases like dental caries, periodontal diseases and malocclusion. Research with monozygotic twins who share the same genetic pool and similar environmental factors estimates the expression of a particular trait by disentangling the shared genetic coding and environmental contributing features. Monozygotic twin pairs may not always be a look alike in resemblance or other features given that fact that the original zygotic genome might be altered due to epigenetic and environmental factors. This case report elaborates three monozygotic twins from a unique village of twins who differ in their occlusal characteristics.
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We conducted a community-based cross-sectional study to evaluate the role of genetics in determining the individual difference in total testosterone and sex hormone-binding globulin levels. Study participants comprised 730 Korean men consisting of 142 pairs of monozygotic twins, 191 pairs of siblings, and 259 father-offspring pairs from 270 families who participated in the Healthy Twin study. Serum concentration of total testosterone and sex hormone-binding globulin were measured by chemiluminescence immunoassay, and free testosterone and bioavailable testosterone were calculated using Vermeulen's method. Quantitative genetic analysis based on a variance decomposition model showed that the heritability of total testosterone, free testosterone, bioavailable testosterone, and sex hormone-binding globulin were 0.56, 0.45, 0.44, and 0.69, respectively after accounting for age and body mass index. Proportions of variance explained by age and body mass index varied across different traits, from 8% for total testosterone to 31% for sex hormone-binding globulin. Bivariate analysis showed a high degree of additive genetic correlation (ρG = 0.67) and a moderate degree of individual-specific environmental correlation (ρE = 0.42) between total testosterone and sex hormone-binding globulin. The findings confirmed the important role of genetics in determining the individually different levels of testosterone and sex hormone-binding globulin during adulthood in Korean men as found in non-Asian populations, which may suggest that common biologic control for determining testosterone level directly or indirectly through binding protein are largely shared among different populations.
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Objective To investigate both genetic and environmental influences on the exercise participation and sedentary behavior in Qingdao,Shandong province and 326 in Lishui, Zhejiang province. Methods 568 twin pairs,including 242 in Qingdao and 326 in Lishui,were studied. Exercise participation was measured by two questions on the frequency and intensity and then divided into two groups. Sedentary behavior was measured by one question as‘how long do you spend on sitting every day’. Variance component models based on twins was used to estimate the genetic and environmental factors on these traits. Results The average age in monozygotic twins was(41.14 ± 10.11)while in dizygotic twins it was(41.23 ± 9.89). Genetic factors accounted 78%(35%-96%)and 59%(0-94%)for exercise participation variance in Qingdao and Lishui in people aged between 20 and 40. However,there were no heritability noticed on physical activity in people older than 40 years of age. Rates of heritability on sedentary behavior in Qingdao and Lishui were 68%(59%-75%)and 32%(7%-62%),respectively. Conclusion Results from the study suggested that sedentary behavior in Chinese people was influenced by genetic factors,which could also explain much of the exercise participation variance in people aged between 20 and 40.
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Objective To investigate both genetic and environmental influences on the exercise participation and sedentary behavior in Qingdao,Shandong province and 326 in Lishui, Zhejiang province. Methods 568 twin pairs,including 242 in Qingdao and 326 in Lishui,were studied. Exercise participation was measured by two questions on the frequency and intensity and then divided into two groups. Sedentary behavior was measured by one question as‘how long do you spend on sitting every day’. Variance component models based on twins was used to estimate the genetic and environmental factors on these traits. Results The average age in monozygotic twins was(41.14 ± 10.11)while in dizygotic twins it was(41.23 ± 9.89). Genetic factors accounted 78%(35%-96%)and 59%(0-94%)for exercise participation variance in Qingdao and Lishui in people aged between 20 and 40. However,there were no heritability noticed on physical activity in people older than 40 years of age. Rates of heritability on sedentary behavior in Qingdao and Lishui were 68%(59%-75%)and 32%(7%-62%),respectively. Conclusion Results from the study suggested that sedentary behavior in Chinese people was influenced by genetic factors,which could also explain much of the exercise participation variance in people aged between 20 and 40.
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OBJETIVO: Verificar se as concentrações de glicose e insulina em jejum são reguladas pela aptidão cardiorrespiratória (VO2máx), independentemente dos efeitos genéticos. MÉTODOS: Dados de 38 pares de gêmeos monozigóticos (11 a 18 anos) foram analisados transversalmente. Os participantes foram submetidos a um teste de esforço máximo com ergoespirometria aberta (MedGraphics VO2000® - Medical Graphics Corp., St. Paul, MN) e à coleta de sangue para estimar a concentração de glicose e insulina em jejum. A zigosidade foi determinada por intermédio da investigação de concordância dos gêmeos em relação a 15 marcadores genéticos polimórficos. Nove pares demonstraram diferença média intrapar para o consumo máximo de oxigênio ≥10mL.kg-1.min-1 e foram divididos em dois grupos, de alta e baixa aptidão. Os grupos foram comparados a partir do teste pareado de Wilcoxon, tendo em vista a assimetria dos dados. RESULTADOS: Em média, os gêmeos do grupo de alta aptidão apresentaram consumo máximo de oxigênio 17% superior (13,5±3,7mL.kg-1.min-1) a seus irmãos menos aptos. Não houve diferença entre os grupos para as concentrações de insulina (36,5±34,6 versus 25,3±13,7mg/dL; p<0,813), porém, os gêmeos mais aptos demonstraram menor concentração de glicose do que seus contrapares menos aptos (82,9±7,3 versus 86,7±7,6mg/dL; p<0,010). CONCLUSÕES: Neste estudo, caracterizado como caso-controle (gêmeos monozigóticos discordantes), o irmão com menor aptidão cardiorrespiratória apresentou maior concentração de glicose em jejum, sugerindo que a baixa aptidão cardiorrespiratória está associada a distúrbios no metabolismo de glicose.
OBJECTIVE: To determine if glucose and insulin concentrations are regulated by cardiorespiratory fitness (VO2max) regardless of their genetic effects. METHODS: This cross-sectional study enrolled 38 pairs of young monozygotic twins (11 to 18 years-old). All subjects underwent a progressive maximal exercise test on a treadmill to determine the VO2max with gas exchange analysis (MedGraphics VO2000® - Medical Graphics Corp., St. Paul, MN). Blood samples were drawn after fasting to determine glucose and insulin levels. Monozygosity was confirmed by genotyping 15 informative genetic markers. Nine pairs had at least 10mL.kg-1.min-1 difference in VO2max and were divided into the more and less active group, according to their VO2max. Mean differences between more and less active groups were evaluated by Wilcoxon's test for paired data. RESULTS: On average, twins from the more active group presented a 17% (13.5±3.7mL.kg-1.min-1) higher VO2max compared to their less active siblings. No significant differences were observed between the groups for fasting insulin (36.5±34.6 versus 25.3±13.7mg/dL; p<0.813). However, the more active twins had lower fasting glucose than the less active ones (82.9±7.3 versus 86.7±7.6mg/dL; p<0.010). CONCLUSIONS: In this case-control study (discordant monozygotic twins), the less active co-twins were characterized by higher fasting plasma glucose levels. This implies that poor cardiorespiratory fitness can be associated with defective glucose metabolism regardless of genetic factors.
OBJETIVO: Verificar si las concentraciones de glucosa e insulina en ayuno son reguladas por la aptitud cardiorrespiratoria (VO2máx), independiente de los efectos genéticos. MÉTODOS: Datos de 38 pares de gemelos monocigóticos (11 a 18 años) fueron analizados transversalmente. Los participantes fueron sometidos a una prueba de esfuerzo máximo con ergoespirometría abierta (MedGraphics VO2000® Medical Graphics Corp., St. Paul, MN) y a la recolección de sangre para estimar la concentración de glucosa e insulina en ayuno. La cigosidad fue determinada por medio de la investigación de concordancia de los gemelos respecto a 15 marcadores genéticos polimórficos. Nueve pares demostraron diferencia mediana intrapares para el consumo máximo de oxígeno ≥10mL.kg-1.min-1 y fueron divididos en dos grupos, de alta y baja aptitud. Los grupos fueron comparados a partir de la prueba pareada de Wilcoxon, teniendo en vista la asimetría de los datos. RESULTADOS: En promedio, los gemelos del grupo de alta aptitud presentaron consumo máximo de oxígeno el 17% superior (13,5±3,7mL.kg-1.min-1) a sus hermanos menos aptos. No hubo diferencia entre los grupos para las concentraciones de insulina (36,5±34,6 versus 25,3±13,7mg/dL; p<0,813), pero los gemelos más aptos demostraron menor concentración de glucosa que sus contrapares menos aptos (82,9±7,3 versus 86,7±7,6mg/dL; p<0,010, respectivamente). CONCLUSIONES: En este estudio, caracterizado como caso-control (gemelos monocigóticos discordantes), el hermano con menor aptitud cardiorrespiratoria presentó mayor concentración de glucosa en ayuno, sugiriendo que la baja aptitud cardiorrespiratoria está asociada a disturbios en el metabolismo de glucosa.
Subject(s)
Adolescent , Child , Female , Humans , Male , Glucose/metabolism , Heart/physiology , Physical Fitness , Respiratory Physiological Phenomena , Twins, Monozygotic , Case-Control Studies , Cross-Sectional StudiesABSTRACT
The aim of this study was to survey multiple birth data and to analyze the recent trends of multiple births and its consequences on perinatal problems in Korea from 1991 to 2008. Data were obtained from the Korean Statistical Information Service. The total number of multiple births showed increasing trends. The multiple birth rate was maintained within less than 10.0 for the decade from 1981 to 1990. However, it increased gradually to reach 27.5 in 2008. The maternal age for multiple births was higher than for total live births. The mean birth weight of the total live births was 3.23 kg; for the multiple births it was 2.40 kg in 2008. The incidence of low birth weight infants (LBWI) among total live births was 3.8% in 2000 and 4.9% in 2008. For multiple births it was 49.2% and 53.0% during the same years. The incidence of preterm births among total live births was 3.8% in 2000 and 5.5% in 2008; for the multiple births it was 38.3% and 51.5% during the same years. The incidence of multiple births and its consequences on perinatal problems (preterm, LBWI, and advanced-maternal age) have been increased steadily over the last two decades in Korea.