遗传和环境因素对青少年脑灰质容积和皮层厚度影响的双生子研究北大核心CSCD

目的通过双生子法探索遗传和环境因素对青少年脑灰质容积、皮层厚度的影响。方法采用横断面研究设计,募集12~18岁双生子。采血液标本提取DNA进行卵型鉴定;采用韦氏儿童智力量表中国修订版进行智商测定;用3.0 T MRI进行头颅结构扫描,采集全脑166层矢状位图像并处理计算个体脑皮层分区灰质容积、皮层厚度;使用双生子结构方程分析遗传和环境对脑灰质容积、皮层厚度的影响。结果纳入57对双生子,其中同卵双生子30对,异卵双生子27对。灰质容积的最佳模型为AE模型,其中各脑区遗传度均有统计学意义(P<0.01);皮层厚度的最佳模型为ACE模型,各脑区中仅双侧扣带回及右侧额叶遗传度有统计学意义(P<0.05),其他脑区遗传度无统计学意义(P>0.05)。相比较影响各脑区皮层厚度的遗传度(A)、共享环境因素贡献度(C)与特异性环境因素(E),特异性环境因素(E)贡献度明显上升。结论在灰质容积和皮层厚度中,青少年脑的可塑性变化可能主要体现在皮层厚度改变上;遗传因素对灰质容积的影响主要驱动因素为皮层面积扩张,而非皮层厚度。     

精神分裂症的双生子研究进展

本文简述了近年来精神分裂症双生子在遗传、发育等病因病理机制及临床方面的研究进展。     

双生子卵型鉴定方法的研究进展

双生子卵型鉴定对于区分环境因素和遗传因素对于疾病或者某一性状形成中的作用是很重要的。相似诊断法、问卷调查法、基因诊断法是目前主要的三种卵型鉴定方法。基因诊断法如短串联重复序列(STR)研究结果显示其准确率达到99%以上,目前成为金标准。对于大规模的双生子研究多采用多种方法综合诊断卵型。问卷调查法简便、费用低,成为双生子卵型中主要的研究方法。     

精神分裂症12对双生子调查分析

目的：了解精神分裂症双生子同病率情况。方法；对12例精神分裂症双生子进行同病率调查。结果：单卵同病率（CMZ）为44.4%，二卵同病率（CDZ）为33.3%。单卵同病的两患者首次发病年龄较接近。结论：精神分裂症的病因中，遗传因素是一个重要方面。     

儿童青少年品行障碍的双生子研究进展

本文综述了近期儿童青少年品行障碍及其相关行为的病因学的双生子研究进展。品行障碍及其相关行为的发生在很大程度上受遗传因素和环境因素的影响,几乎各种危险因素与品行障碍的联系都同时受到遗传因素和环境因素的共同介导。     

青少年抑郁情绪影响因素的双生子研究

目的探讨遗传及环境因素对青少年抑郁情绪的影响。方法采用贝克抑郁量表(Beck depression inventory,BDI)对重庆市107对11~18岁双生子的抑郁情绪进行评定,采用一般情况问卷、父母的养育方式和维度问卷(parenting styles and dimensions questionaire,PSDQ)、家庭压力问卷(family stresses questionnaire,FSQ)、家庭亲密度与适应性量表(family adaptability and cohesion evaluation scale 2nd edition Chinese version,FACES II-CV)、应激生活事件(stressful life event,SLE)等量表调查环境因素,采集双生子静脉血标本提取DNA以进行卵型鉴定。构建单因素结构方程模型,分析加性遗传因素(A)、共享环境因素(C)、特殊环境因素(E)对双生子抑郁情绪的影响。结果双生子的抑郁情绪与父亲受教育程度(r=-0.15,P=0.03)、母亲受教育程度(r=-0.17,P=0.01)、权威型养育方式(r=-0.18,P0.01)、家庭适应性(r=-0.27,P0.01)及亲密度(r=-0.20,P0.01)呈负相关,与家庭压力呈正相关(r=0.12,P=0.04),与应激生活事件无统计学相关性(P0.05)。结构方程示,在抑郁情绪总变异方差中加性遗传效应占0.37(95%CI:0.14~0.57),个体特殊环境因素占0.63(95%CI:0.43~0.86)。结论抑郁情绪与父母权威型养育方式、家庭适应性负性相关,与家庭压力正性相关;青少年抑郁情绪受加性遗传和特殊环境因素的共同影响,但受特殊环境的影响更大。     

儿童认知加工速度的双生子研究

目的 运用双生子法探讨遗传和环境因素对儿童青少年认知加工速度的影响.方法 采用韦氏儿童智力量表Ⅳ(WISC-Ⅳ)中的编码测验和符号检索评定333对6～16岁双生子的认知加工速度特点.应用结构方程模型分析遗传和环境因素对认知加工速度的影响.结果 6～16岁儿童青少年的编码测验遗传度为0.28,在不同的性别(男:女为0.09:0.00)和年龄(10～16岁:6～9岁为0.24:0.38)的遗传度差异较符号检索的差异小;符号检索的遗传度为0.61,男生(0.47)受遗传影响大于女生(0.25),6～9岁的儿童符号检索主要受遗传影响(0.63),而10～16岁的儿童青少年符号检索主要受共享环境影响(0.56).结论 认知加工速度有中～高度的遗传度,编码测验和符号检索可能反映加工速度的不同维度.     

双相情感障碍分子遗传学研究新进展

双相情感障碍(BD)是两个主要的精神障碍之一。双生子、寄养子和家系研究已经表明遗传因素是该病的病因因素之一；然而．高达61％～75％的双生子的同病率和仅有1．5％～15．5％的一级亲属危险度提示．BD不是由单一主效基因而是由多因素所致的遗传性疾病。精神药理学的证据．像单胺再摄取抑制剂的抗抑郁效应和单胺受体拮抗剂的抗躁狂效应．建立了单胺能通路参与了BD的病理生理机制。     

精神分裂症遗传学研究进展

精神分裂症是一种复杂的由多种因素所致的精神障碍，其特征是思维、情感与行为的相互分裂。家系调查、双生子及寄养子研究均支持遗传因素与发病有关。近年来发现人类染色体上一些区域和基因与精神分裂症的发生有关。     

青岛市中老年双生子轻度认知功能障碍患病率及其与血压的关系

目的调查青岛市中老年双生子轻度认知功能障碍(MCI)的患病率及同病率,并探讨其患病率与血压的关系,为预防MCI提供参考。方法从青岛市双生子库中招募384对年龄≥40岁的中老年双生子,其中同卵双生子244对,异卵双生子140对。采用一般情况调查表收集其性别、年龄、收缩压、舒张压等资料。采用北京版蒙特利尔认知评价量表(MoCA)评定其认知功能。结果青岛市中老年双生子人群MCI患病率为84.38%;同卵和异卵双生子MCI患病率分别为83.40%、86.07%;MCI同病率为81.51%,同卵和异卵双生子MCI同病率分别为81.97%、80.71%。高收缩压组MCI患病率高于非高收缩压组(χ~2=20.590,P0.01),高舒张压组MCI患病率高于非高舒张压组(χ~2=10.041,P0.01)。结论青岛市中老年双生子MCI患病率较高,双生子的不同卵型可能与MCI同病率无关,高血压可能增加患MCI的风险。     

Genetic or epigenetic difference causing discordance between monozygotic twins as a clue to molecular basis of mental disorders

Classical twin research focused on differentiating genetic factors from environmental factors by comparing the concordance rate between monozygotic (MZ) and dizygotic twins. On the other hand, recent twin research tries to identify genetic or epigenetic differences between MZ twins discordant for mental disorders. There are a number of reports of MZ twins discordant for genetic disorders caused by genetic or epigenetic differences of known pathogenic genes. In the case of mental disorder research, for which the causative gene has not been established yet, we are trying to identify the 'pathogenic gene' by comprehensive analysis of genetic or epigenetic difference between discordant MZ twins. To date, no compelling evidence suggesting such difference between MZ twins has been reported. However, if the genetic or epigenetic difference responsible for the discordant phenotype is found, it will have impact on the biology of mental disorder, in which few conclusive molecular genetic evidences have been obtained.     

A Graves' Disease of Identical Twins with Mental Disorder

Abstract: We present here the clinical cases of identical twins with Graves' disease associated with various mental disorders. They showed restlessness, hyperexcitability, emotional instability, anxiety, depressive state, obsessive-compulsive manifestations, delusions of persecution reference. In the case of twin A, the psychiatric symptoms Graves' disease were in parallel with their clinical course, his psychiatric symp toms disappeared after a subtotal thyroidectomy.
In the case of twin B, however, the psychiatric symptoms had almost disappeared during the period of hypothyroidism for two months after a subtotal thyroidectomy, but the symptoms recurred in spite of the data of euthyroidism in blood examinations after that period of time.
It was suggested that the psychiatric symptoms of twin B were due to the euthyroid Graves' disease. The close resemblance of the psychiatric symptoms in both twin A B might be based on the same genetic disposition due to their being identical twins.     

A Graves' disease of identical twins with mental disorder

We present here the clinical cases of identical twins with Graves' disease associated with various mental disorders. They showed restlessness, hyperexcitability, emotional instability, anxiety, depressive state, obsessive-compulsive manifestations, and delusions of persecution and reference. In the case of twin A, the psychiatric symptoms and Graves' disease were in parallel with their clinical course, and his psychiatric symptoms disappeared after a subtotal thyroidectomy. In the case of twin B, however, the psychiatric symptoms had almost disappeared during the period of hypothyroidism for two months after a subtotal thyroidectomy, but the symptoms recurred in spite of the data of euthyroidism in blood examinations after that period of time. It was suggested that the psychiatric symptoms of twin B were due to the euthyroid Graves' disease. The close resemblance of the psychiatric symptoms in both twin A and B might be based on the same genetic disposition due to their being identical twins.     

Suicide in twins

Suicide appears to cluster in families, suggesting that genetic factors may play a role in this behavior. We studied 176 twin pairs in which one or both twins had committed suicide. Seven of the 62 monozygotic twin pairs were concordant for suicide compared with two of the 114 dizygotic twin pairs (11.3% vs 1.8%). The presence of psychiatric disorder in the twins and their families was examined in a subsample of 11 twin pairs, two of whom were concordant for suicide. Eleven of these 13 twin suicide victims had been treated for psychiatric disorder, as had eight of their nine surviving cotwins. In addition, twins in 10 pairs had other first- or second-degree relatives who had been treated for psychiatric disorder. Thus, these twin data suggest that genetic factors related to suicide may largely represent a genetic predisposition for the psychiatric disorders associated with suicide. However, they leave open the question of whether there may be an independent genetic component for suicide.     

Essential tremor in twins: an assessment of genetic vs environmental determinants of etiology.

OBJECTIVE: To determine the relative contribution of genetics and environment to essential tremor using a twin study method. METHODS: Twins with postural or kinetic tremor were identified by movement disorders specialists during the conduct of a study investigating PD in members of the National Academy of Sciences and National Research Council World War II Veteran Twins Registry. The diagnosis of essential tremor was made by consensus using established diagnostic criteria. RESULTS: A total of 196 twins had postural or kinetic tremor on examination. Of these, 137 had PD or had a twin with PD and were excluded from this study. Thirty-three others were excluded because of incomplete data for their twin. Sixteen twin pairs were identified in which at least one twin had essential tremor. Pairwise concordance in monozygotic twins was approximately two times that in dizygotic twins (0.60 monozygotic, 0.27 dizygotic). CONCLUSION: This pattern is consistent with a genetic cause of essential tremor. Because monozygotic concordance is not 100%, environmental factors may also play a role in the cause of the disease.     

Heritability of Schizophrenia and Schizophrenia Spectrum Based on the Nationwide Danish Twin Register

Background

Twin studies have provided evidence that both genetic and environmental factors contribute to schizophrenia (SZ) risk. Heritability estimates of SZ in twin samples have varied methodologically. This study provides updated heritability estimates based on nationwide twin data and an improved statistical methodology.

Twins discordant for schizophrenia: psychopathology of the non-schizophrenic co-twins

Objective: Patients with schizophrenia are more likely to suffer from mood and anxiety disorders compared with the general population. We explored the aetiology of this comorbidity using a twin study design. Method: We applied an additive genetic + unique environment (AE) random effects model in the analysis of 35 non‐schizophrenic co‐twins from pairs discordant for schizophrenia, and 131 control twins. Results: Non‐schizophrenic co‐twins had significantly increased rates of depression (P = 0.006) and anxiety disorders (P = 0.021) compared with the control twins. Conclusion: Our results provide evidence for a familial association between schizophrenia and anxiety and depression. This could reflect common aetiological factors contributing to each of the disorders. Future studies should attempt to investigate the relative genetic and environmental contribution to the shared risk factors for schizophrenia, mood and anxiety disorders.     

Genetic and environmental influences on the co‐morbidity between depression,panic disorder,agoraphobia, and social phobia: a twin study

Background: Major depression (MD) and anxiety disorders such as panic disorder (PD), agoraphobia (AG), and social phobia (SP) are heritable and highly co‐morbid. However, the relative importance of genetic and environmental etiology of the covariation between these disorders, particularly the relationship between PD and AG, is less clear. Methods: This study measured MD, PD, and AG in a population sample of 5,440 twin pairs and 1,245 single twins, about 45% of whom were also scored for SP. Prevalences, within individual co‐morbidity and twin odds ratios for co‐morbidity, are reported. A behavioral genetic analysis of the four disorders using the classical twin design was conducted. Results: Odds ratios for MD, PD, AG, and SP in twins of individuals diagnosed with one of the four disorders were increased. Heritability estimates under a threshold‐liability model for MD, PD, AG, and SP respectively were .33 (CI: 0.30–0.42), .38 (CI: 0.24–0.55), .48 (CI: 0.37–0.65), and .39 (CI: 0.16–0.65), with no evidence for any variance explained by the common environment shared by twins. We find that a common genetic factor explains a moderate proportion of variance in these four disorders. The genetic correlation between PD and AG was .83. Conclusion: MD, PD, AG, and SP strongly co‐aggregate within families and common genetic factors explain a moderate proportion of variance in these four disorders. The high genetic correlation between PD and AG and the increased odds ratio for PD and AG in siblings of those with AG without PD suggests a common genetic etiology for PD and AG. Depression and Anxiety 26:1004–1011, 2009. Published 2009 Wiley‐Liss, Inc.     

The occurrence of epilepsy and febrile seizures in Virginian and Norwegian twins

Twin studies provide an efficient method for examining the importance of genetic and environmental factors in the etiology of disorders such as epilepsy. Population-based twin registries are especially valuable for studies of this type since effects of reporting and self-selection biases on the resulting data are minimized. Among 14,352 twin pairs contained in the Virginia and Norwegian twin panels for whom questionnaire information was available, there was a history of epilepsy in one or both members of 286 pairs; febrile seizures were reported in 257 pairs. Analyses of questionnaire data revealed no significant differences in concordance rates between Virginian and Norwegian twins for either epilepsy or febrile seizures. Probandwise concordance rates for epilepsy were 0.19 in monozygotic twins and 0.07 in dizygotic twins. Analogous rates for febrile seizures were 0.33 (monozygotic) and 0.11 (dizygotic). These results provide further evidence that genetic factors do have a role in the expression of epilepsy and febrile seizures.     

Abnormal-pursuit eye movements in schizophrenia. Evidence for a genetic indicator

Disordered smooth-pursuit eye movements occur in a high percentage of schizophrenic patients and their first-degree relatives. A Test of the hypothesis that these disorders represent a genetic indicator of schizophrenia was undertaken by testing pursuit eye movements in a sample of monozygotic and dizygotic twins discordant for clinical schizophrenia. Deviant eye tracking is significantly concordant within monozygotic twin pairs, and less so with dizygotic twin pairs discordant for schizophrenia. A genetic interpretation is consistent with these results.