遗传与环境因素对儿童个性影响的双生子研究

本文采用艾森克个性问卷（儿童）对８８对健康的偶内性别相同的７—１４岁双生儿童的个性特征进行了调查。结果表明：正常儿童的个性特征在Ｎ、Ｅ量表方面主要受遗传因素影响，遗传因素对Ｐ量表的影响小于Ｎ、Ｅ量表的影响，而Ｌ量表则主要受环境因素影响。     

遗传-环境效应对学龄期女孩唾液睾酮影响的双生子研究

目的探讨遗传和环境因素对学龄期女孩唾液睾酮水平的影响,以及年龄在其中的作用。方法以2006年-2007年北京中小学募集的6—12岁双生子女孩为研究对象,共获得双生子78对（同卵双生63对,异卵双生15对）,平均年龄为8．92±1．90岁。以DNA进行卵性鉴定,酶联免疫法测量唾液睾酮水平,拟合结构方程模型估计唾液睾酮遗传度,并检验年龄的作用。结果学龄期女孩唾液睾酮水平从6岁时的17．47pg／ml增长为12岁时的63．98pg／ml,其中9—11岁增长迅速;AE—age模型为最适模型,年龄作用占总方差的34．54％,遗传和环境方差分别占41．50％和23．96％。扣除年龄作用,学龄期女孩唾液睾酮遗传度为63．4％。结论学龄期女孩唾液T水平受到遗传和环境因素的共同作用,遗传效应尤为显著;年龄对其唾液T水平有重要影响。     

行为遗传的双生子研究

本研究采用双生子法人类几项行为(简单的生理—心理动作、记忆、智能、个性)进行了研究,以探讨上述行为中遗传与环境因素的不同影响。结果证明,上述行为均有不同程度的遗传倾向,但这种倾向随着行为的简单到复杂及与环境接触时间的增长有所减弱。     

双生子的身高等形态指标的遗传度及身高的影响因素和预测的分析

目的通过对双生子身高等形态指标监测观察,了解遗传与环境对身高的影响及身高预测。方法对监测的每个双生儿和儿童按全国九市体格发育调查方案进行身高、体重、臂围的测试,并进行遗传度计算,统计分析采用Spss10.0 For Windows软件完成。结果共调查双生儿267对,同卵和异卵双生儿的身高在各年龄组呈正态分布,男女双生儿童身高、体重、臂周发育同正常儿童基本一致,同卵双生子与父母的身高相关素数明显大于异卵双生与父母之间的相关系数,异卵双生儿与母亲的相关系数大于异卵双生与父亲的相关系数,身高及遗传的影响明显大于臂周和体重。结论父母身高与子女身高呈明显正相关关系,有加权作用,初步推测子女身高其线性方程,影响双生儿身高的最大因素为父母身高、民族因素。     

双生子方法在遗传流行病学研究中的应用及进展

双生子研究是确定复杂疾病和性状遗传学基础的重要方法之一。经典的双生子研究方法可以确定基因和环境对表型的相对作用大小,但随着遗传统计学、计算机以及分子生物学技术的发展,不仅使经典的双生子研究方法得到了拓展,而且还开辟了一些新的研究方法和理论,如基于结构化模型方法的应用、多变量设计、双生子对内病例对照研究、利用双生子及其家系资料所进行的遗传流行病学和分子遗传学研究等等。本文分别对经典双生子研究方法及拓展以及双生子研究在复杂疾病和性状的连锁和关联研究中的应用分别进行了综述。     

儿童青少年智力的双生子研究

目的 应用双生子法探讨遗传和环境因素对儿童青少年智力影响.方法 采用中国修订版-韦氏儿童智力量表评定6～16岁333对双生子的智力特点.应用结构方程模型分析遗传和环境因素对智力的影响.结果 6～16岁儿童青少年的总智商(intelligence quotient,IQ)遗传度为0.43,其中言语智商(verbal intelligence quotient,VIQ)遗传度为0.37,而遗传因素对操作智商(performance intelligence quotient,PIQ)影响甚小.10～16岁的青少年智力遗传度大于6～9岁的儿童(IQ:0.82 vs 0.00,VIQ:0.80 vs 0.00,PIQ:0.51 vs 0.00).男性的言语智商(0.47)受遗传影响大于女性(0.05);而在男性和女性中,操作智商均主要受共享环境的影响.结论 在儿童青少年时期,总智商和言语智商有中度的遗传度,而共享环境因素对操作智商的影响更大;但智商总分及言语智商和操作智商分测试分在年龄较大的青少年的遗传度都明显高于年龄较小的儿童.     

儿童青少年智力的双生子研究

目的 应用双生子法探讨遗传和环境因素对儿童青少年智力影响.方法 采用中国修订版-韦氏儿童智力量表评定6～16岁333对双生子的智力特点.应用结构方程模型分析遗传和环境因素对智力的影响.结果 6～16岁儿童青少年的总智商(intelligence quotient,IQ)遗传度为0.43,其中言语智商(verbal intelligence quotient,VIQ)遗传度为0.37,而遗传因素对操作智商(performance intelligence quotient,PIQ)影响甚小.10～16岁的青少年智力遗传度大于6～9岁的儿童(IQ:0.82 vs 0.00,VIQ:0.80 vs 0.00,PIQ:0.51 vs 0.00).男性的言语智商(0.47)受遗传影响大于女性(0.05);而在男性和女性中,操作智商均主要受共享环境的影响.结论 在儿童青少年时期,总智商和言语智商有中度的遗传度,而共享环境因素对操作智商的影响更大;但智商总分及言语智商和操作智商分测试分在年龄较大的青少年的遗传度都明显高于年龄较小的儿童.     

儿童青少年智力的双生子研究

目的 应用双生子法探讨遗传和环境因素对儿童青少年智力影响.方法 采用中国修订版-韦氏儿童智力量表评定6～16岁333对双生子的智力特点.应用结构方程模型分析遗传和环境因素对智力的影响.结果 6～16岁儿童青少年的总智商(intelligence quotient,IQ)遗传度为0.43,其中言语智商(verbal intelligence quotient,VIQ)遗传度为0.37,而遗传因素对操作智商(performance intelligence quotient,PIQ)影响甚小.10～16岁的青少年智力遗传度大于6～9岁的儿童(IQ:0.82 vs 0.00,VIQ:0.80 vs 0.00,PIQ:0.51 vs 0.00).男性的言语智商(0.47)受遗传影响大于女性(0.05);而在男性和女性中,操作智商均主要受共享环境的影响.结论 在儿童青少年时期,总智商和言语智商有中度的遗传度,而共享环境因素对操作智商的影响更大;但智商总分及言语智商和操作智商分测试分在年龄较大的青少年的遗传度都明显高于年龄较小的儿童.     

中国双生子登记系统进展

目的分别在中国北方和南方、城市和农村地区建立四个以人群为基础的双生子登记系统；应用本双生子登记系统，选择成年双生子进行详细调查，开展心脑血管疾病及其相关性状的遗传流行病学研究。方法双生子的登记主要依靠卫生防疫三级保健网络进行覆盖。对于参与详细调查的双生子的募集，不同地区因地制宜．采用不同的方式。结果目前登记系统已登记7423对双生子，并对其中1613对双生子进行详细调查和体检。系统在基线登记的基础上，还建立了一个包含579对双生子的队列。已进行的研究包括成年双生子心脑血管疾病相关中间表型研究、心理学研究、青少年生长发育研究等。结论中国双生子登记系统是目前中国首个以人群为基础的双生子登记系统，它已成为医学和科学研究的一项重要的国际和国内资源。     

儿童青少年智力的双生子研究

目的 应用双生子法探讨遗传和环境因素对儿童青少年智力影响.方法 采用中国修订版-韦氏儿童智力量表评定6～16岁333对双生子的智力特点.应用结构方程模型分析遗传和环境因素对智力的影响.结果 6～16岁儿童青少年的总智商(intelligence quotient,IQ)遗传度为0.43,其中言语智商(verbal intelligence quotient,VIQ)遗传度为0.37,而遗传因素对操作智商(performance intelligence quotient,PIQ)影响甚小.10～16岁的青少年智力遗传度大于6～9岁的儿童(IQ:0.82 vs 0.00,VIQ:0.80 vs 0.00,PIQ:0.51 vs 0.00).男性的言语智商(0.47)受遗传影响大于女性(0.05);而在男性和女性中,操作智商均主要受共享环境的影响.结论 在儿童青少年时期,总智商和言语智商有中度的遗传度,而共享环境因素对操作智商的影响更大;但智商总分及言语智商和操作智商分测试分在年龄较大的青少年的遗传度都明显高于年龄较小的儿童.     

Estimates of asthma heritability in a large twin sample

Background Asthma is a complex disease characterized by symptoms of wheezing, shortness of breath, chest tightness, and cough. Objective To study the relative contribution of genetic and environmental factors in the liability to asthma in a large sample of twins. Methods Data on asthma in 21 135 twin pairs, 3–71 years of age, from the Danish Twin Registry were collected via a multidisciplinary questionnaire survey. Heritability estimates were calculated using variance components models. Results A monozygotic twin had an approximately sixfold increased risk of asthma whereas a dizygotic twin only had an approximately threefold increased risk relative to the general population if his or her co‐twin was affected. The difference was more pronounced among males. Familial aggregation of asthma in children and adolescents was explained mainly by additive genetic factors, but common environment was also important. The heritability of asthma was also substantial in adults aged 20–49 years. In older adults (aged 50–71 years), additive genetic factors did not significantly influence the disease risk. Conclusion Genetic influences on asthma are substantial throughout the life span but the proportion of the disease liability explained by genetic factors is decreased in older adults. Cite this as: S. F. Thomsen, S. van der Sluis, K. O. Kyvik, A. Skytthe, V. Backer, Clinical & Experimental Allergy, 2010 (40) 1054–1061.     

Assessment of heritability for personality,based on a short-form of the Eysenck personality inventory: A study of 12,898 twin pairs

The influence of genetic factors for two personality dimensions was analyzed using data from 12,898 unselected twin pairs of the Swedish Twin Registry. The heritability index was 0.50 (men) and 0.58 (women) for psychosocial instability. Corresponding figures for psychosocial extraversion were 0.54 and 0.66. Thus, about half the phenotypic variation may be attributed to genetic factors.     

Heritability of Obesity‐related Phenotypes and Association with Adiponectin Gene Polymorphisms in the Chinese National Twin Registry

The purpose of this study was to estimate the heritability of obesity‐related phenotypes and investigate the association of adiponectin gene polymorphisms +45T>G and +276G>T with these measures in Chinese twins. 1260 twin pairs were recruited from two cities through the Chinese National Twin Registry System from 2001 to 2005. Two SNPs at the adiponectin locus (+45T>G and +276G>T) were genotyped. Structural equation modeling (SEM) was used to estimate heritability and the best‐fitting variance component model. The regular association among all twins was analysed with generalised estimating equations (GEE). Sib‐transmission/disequilibrium test (TDT) within dizygotic (DZ) twin pairs discordant for their genotype was performed using SEM. Additive genetic, common and unique environmental (ACE) model‐based heritability of body mass index (BMI) was 61%, while additive genetic and unique environmental (AE)‐model‐based heritability of waist circumference (WC) and waist‐hip ratio (WHR) were 75% and 61%, respectively. There was no association of adiponectin gene +45T>G and +276G>T genotypes with obesity‐related phenotypes in all twins or discordant DZ twins. Our twins data did not support that there was an association between adiponectin gene polymorphisms +45T>G and +276G>T and the obesity‐related phenotypes. Further studies are required to better understand the role of adiponectin gene polymorphisms in obesity.     

Genetic and environmental contributions to allergen sensitization in a Chinese twin study

Background Allergic disease is on the rise worldwide. Effective prevention of allergic disease requires comprehensive understanding of the factors that contribute to its intermediate phenotypes, such as sensitization to common allergens. Objective To estimate the degree of genetic and environmental contributions to sensitization to food and aeroallergens. Methods Sensitization was defined as a positive skin prick test to an allergen. We calculated the zygosity‐specific concordance rates and odds ratios (ORs) for sensitization to food and aeroallergens in 826 Chinese twin pairs [472 monozygotic (MZ) and 354 dizygotic (DZ)] aged 12–28 years. We also applied structural equation modelling procedures to estimate genetic and environmental influences on sensitization. Results The concordance rates and risk of sensitization in one twin given the presence vs. the absence of sensitization in the other twin were higher in MZ twins than those in DZ twins. However, a large number of MZ twins were discordant in sensitization to common allergens. These observations suggest both genetic and environmental factors influence sensitization. Consistently, the estimated heritability and individual environmental components of the liability to sensitization ranged from 0.51 to 0.68 and 0.32 to 0.49, respectively, based on the best‐fitted structural equation model. We also observed high phenotypic correlations between sensitization to two aeroallergens (cockroach and dust mite: 0.83) and two food allergens (peanut and shellfish: 0.58), but only moderate correlations for the pairs between sensitization to a food and an aeroallergen (0.31–0.46). The shared genetic and environmental factors between paired sensitizations contribute to the observed correlations. Conclusion We demonstrated that sensitization to common food and aeroallergens were influenced by both genetic and environmental factors. Moreover, we found that paired allergen sensitizations might share some common sets of genes and environmental factors. This study underscores the need to further delineate unique and/or pleiotropic genetic and environmental factors for allergen sensitization.     

遗传与环境因素对儿童内向行为影响的双生子研究

目的 利用双生子设计的定量遗传分析方法探讨遗传因素与环境因素对于儿童内向行为的影响.方法 使用Achenbach儿童行为评定量表家长版本调查了189对成都地区6～16岁双生子的内向行为,采用Holzinger公式计算遗传度,家长评定家庭亲密度和适应性量表、一般健康问卷调查特定环境因素.结果 (1)儿童内向行为遗传度为0.54,年龄、性别与其相关.(2)家庭实际适应性、父母心理健康情况与儿童的内向行为显著相关(r=-0.213,0.250,0.309;Ps＜0.001),母亲心理健康状况为其危险因素(OR=2.483,P=0.008).结论 遗传因素和环境因素对儿童的内向行为均有影响,年龄和性别与遗传度相关,影响儿童内向行为的环境因素包括家庭功能和父母的心理健康水平.     

Relationships between the serum levels of soluble leptin receptor and free and bound leptin in non-pregnant women of reproductive age and women undergoing controlled ovarian hyperstimulation

BACKGROUND: The aim of this study was to investigate the relationships between the serum levels of soluble leptin receptor (SLEPR), and total, free and bound leptin, and the change in the serum SLEPR level during an IVF cycle. METHODS: Serum concentrations of leptin and SLEPR were measured in 50 Japanese women of reproductive age, and 20 patients participating in an IVF programme. The total leptin was fractionated into free and bound portions by gel filtration chromatography. RESULTS: The SLEPR level was negatively correlated with the body mass index (BMI) (r = -0.548, P < 0.0001), total leptin (r = -0.433, P < 0.0001), the percentage of free leptin (r = -0.732, P < 0.0001) and the absolute free leptin concentration (r = -0.506, P < 0.0001). The SLEPR level was positively correlated with the percentage of bound leptin (r = 0.730, P < 0.0001), whereas there was little variation in the absolute bound leptin concentration, regardless of the BMI or SLEPR concentration. During the IVF cycle, total and free leptin elevated during maximal ovarian stimulation, whereas there was no significant difference in the SLEPR concentration. CONCLUSIONS: The results demonstrate a skillful mechanism where a change in the serum SLEPR level regulates, in part, the biological activity of leptin in the circulation.     

Obstetric outcome of twin pregnancies after in-vitro fertilization: a matched control study in four Dutch university hospitals

In singleton pregnancies after in-vitro fertilization (IVF), increased rates of obstetric and perinatal complications have been reported. Studies that compared IVF twin pregnancies with spontaneously conceived twins have yielded conflicting results. We compared 96 IVF twin pregnancies to 96 controls after elaborate matching. The design of our study precluded matching by zygosity. The monozygosity rate was higher in the control group and this implies that beforehand the risk for a less favourable outcome in the control group was higher than in the IVF group. However, the average birthweight of the IVF children was less than that of children in the control group (P = 0.04). This was not due to more intrauterine growth retardation in the IVF group. The mean gestational age at birth was 5 days shorter in IVF than control pregnancies, and although this difference was not significant it might explain the lower birthweight in the IVF group. The discordance rate in the IVF group was significantly increased. We found no difference in perinatal mortality and morbidity. We conclude that this study provides further evidence for a different outcome of IVF twin pregnancies in comparison with spontaneously conceived twin pregnancies.     

Perinatal outcome of 12,021 singleton and 3108 twin births after non-IVF-assisted reproduction: a cohort study

Perinatal outcome of pregnancies caused by assisted reproduction technique (ART) is substantially worse when compared with pregnancies following natural conception. We investigated the possible risks of non-IVF ART on perinatal health. We conducted a retrospective cohort study with two exposure groups: a study group of pregnancies after controlled ovarian stimulation (COS), with or without artificial insemination (AI), and a naturally conceived comparison group. We used the data from the regional registry of all hospital deliveries in the Dutch-speaking part of Belgium during the period from January 1993 until December 2003 to investigate differences in perinatal outcome of singleton and twin pregnancies. 12 021 singleton and 3108 twin births could be selected. Naturally conceived subjects were matched for maternal age, parity, fetal sex and year of birth. The main outcome measures were duration of pregnancy, birth weight, perinatal morbidity and perinatal mortality. Our overall results showed a significantly higher incidence of prematurity (<32 and <37 weeks), low and very low birth weight, transfer to the neonatal intensive care unit and most neonatal morbidity parameters for COS/AI singletons. Twin pregnancies resulting from COS/AI showed an increased rate of neonatal mortality, assisted ventilation and respiratory distress syndrome. After excluding same-sex twin sets, COS/AI twin pregnancies were at increased risk for extreme prematurity and very low birth weight. In conclusion, COS/AI singleton and twin pregnancies are significantly disadvantaged compared to naturally conceived children.