中国成年双生子体质指数的分布特征

目的 描述中国双生子登记系统（CNTR）成年双生子BMI的分布特征,探索BMI在双生子人群中的特殊分布规律,为超重及肥胖高危因素分析和制定防制策略提供线索和基础资料。方法 选自CNTR中2010-2018年完成问卷调查的双生子对,纳入≥ 18岁具有完整双生子对登记信息,且身高、体重等关键变量无缺失或异常者进行分析,共计32 725对成年双生子。描述CNTR项目成年双生子BMI的人群、地区分布特征及双生子对内成员BMI差异的分布现况。结果 研究对象年龄（34.6±12.4）岁,同性别双生子对79.7%。研究对象平均BMI为22.5 kg/m²,超重率为23.7%,肥胖率为4.9%。男性、50~59岁组、北方地区、低文化程度者、在婚者的双生子超重率和肥胖率相对更高（P<0.001）。同卵和异卵间差异无统计学意义,但先出生的双生子超重和肥胖率略高于后出生者（P<0.05）。同性别双生子对内分析发现,对内BMI差异与年龄呈正相关（趋势性检验P<0.001）,异卵差异高于同卵,且卵型间差异随年龄增长发生变化。BMI一致率存在卵型差异（P<0.05）,同卵高于异卵。结论 本研究的双生子人群BMI的分布存在人群和地区差异;BMI为可遗传的性状,且遗传作用可能随年龄而变化。     

利用结构方程模型计算成年双生子饮酒遗传度的研究

目的 分析遗传和环境因素对饮酒的影响。方法 对2015-2018年中国双生子登记系统募集的9 231对成年同性别双生子,利用结构方程模型对饮酒相关变量进行拟合,估计遗传因素和环境因素对其的影响。结果 共纳入9 231对双生子进行分析,其中同卵双生子6 085对。同卵双生子年龄（36.91±13.07）岁,男性占56.80%;异卵双生子年龄（35.22±12.48）岁,男性占55.91%。双生子高风险饮酒者共350人,占1.90%,中风险饮酒者共367人,占1.99%。中风险饮酒受加性遗传、双生子共享环境及各自环境的影响,遗传度为24.3%（95% CI：0～56.8%）,共享环境可解释50.7%（95% CI：20.4%～79.0%）,特殊环境可解释24.9%（95% CI：18.3%～36.5%）。而高风险饮酒则主要受双生子共享环境及各自特殊环境的影响,共享环境可解释75.6%（95% CI：69.6%～80.8%）,特殊环境可解释24.4%（95% CI：19.2%～30.4%）。中高风险饮酒的遗传度具有一定的性别差异,男性中遗传度为30.8%（95% CI：9.8%～53.5%）,在女性中则主要受到环境的影响。结论 中高风险饮酒行为主要受环境影响,有一定的性别差异,且随着饮酒量的增加,环境对于饮酒行为的影响作用更趋显著。     

青岛和丽水地区双生子研究：体育活动和静坐行为的遗传度

目的 探讨山东省青岛和浙江省丽水地区双生子人群体育活动和静坐行为的遗传度。方法 使用两地区2004 年随访的有卵型信息的双生子人群（共568 对,其中青岛242 对,丽水326 对）横断面调查资料,通过问卷调查得到体育活动和静坐行为信息。采用基于双生子的方差组分分析方法计算双生子表型的遗传度。结果 同卵双生子有367 对,异卵双生子有201 对,双生子中男性571 人,女性565 人。同卵双生子年龄为（41.14±10.11）岁,异卵双生子年龄为（41.23±9.89）岁。青岛和丽水地区＜40 岁人群的体育活动遗传度为78%（35%～96%）、59%（0～94%）,≥40 岁人群体育活动不受遗传影响。青岛和丽水地区静坐行为遗传度分别为68%（59%～75%）、32%（7%～62%）。结论 青岛和丽水地区人群静坐行为水平受遗传影响,且遗传因素在20～40 岁人群的体育活动水平中有着重要作用。     

中国双生子人群2型糖尿病分布特征

目的描述中国双生子登记系统(CNTR)双生子的2型糖尿病分布特征, 为揭示遗传和环境因素对2型糖尿病的影响提供线索和依据。方法 CNTR 2010-2018年项目登记的所有双生子中, 纳入≥30岁且有完整登记信息的18 855对双生子作为研究对象。采用随机效应模型描述2型糖尿病的人群、地区分布特征以及对内一致性的分布。结果研究对象年龄(42.8±10.2)岁, 同卵双生子(MZ)10 339对, 异卵双生子(DZ)8 516对。全人群中2型糖尿病报告患病率为2.2%, MZ和DZ报告患病率差异无统计学意义。双生子对内分析发现2型糖尿病MZ同病率为38.2%, DZ为16.0%, 差异有统计学意义(P<0.001), 在不同性别、年龄和地区中MZ同病率均大于DZ(P<0.05)。进一步分层分析, 在北方, 仅在<60岁人群中发现MZ同病率大于DZ(P<0.05);而南方, ≥60岁男性MZ同病率也大于DZ(P<0.05)。结论本研究的双生子人群2型糖尿病报告患病率低于一般人群, 在不同性别、年龄和地区中均提示遗传因素在2型糖尿病中起作用, 但其作用大小可能不...     

中国成年双生子高脂血症的分布特征

目的描述中国双生子登记系统(CNTR)成年双生子高脂血症的分布特征, 初步探索遗传和环境因素对高脂血症的影响。方法研究对象来自CNTR在全国11个项目地区募集的双生子, 纳入成年且具有高脂血症信息的69 130名(34 565对)双生子进行分析。采用随机效应模型描述高脂血症的人群、地区分布特征。分别计算不同卵型双生子的高脂血症同病率, 估算遗传度。结果研究对象年龄为(34.2±12.4)岁。双生子人群高脂血症患病率为1.3%(895/69 130)。男性、年长、城镇、已婚、大专及以上文化程度、超重、肥胖、体力活动不足、当前吸烟和曾经吸烟、当前饮酒和曾经饮酒人群中高脂血症患病率较高。双生子对内分析发现, 同卵双生子高脂血症同病率为29.1%(118/405), 高于异卵双生子的18.1%(57/315), 差异有统计学意义(P<0.05)。在不同年龄、地区及性别分层中, 同卵双生子同病率仍呈现高于异卵双生子的趋势。进一步同性别双生子对内分析发现, 在北方组和女性组中, 高脂血症遗传度分别为13.04%(95%CI:2.61%～23.47%)、18.59%(95%CI:4.43%～3...     

中国成年双生子高血压的分布特征

目的描述中国双生子登记系统(CNTR)成年双生子高血压的分布特征, 探索高血压在我国双生子人群中的分布规律, 为探索遗传和环境因素对高血压的作用提供线索。方法研究对象选自2010-2018年于CNTR进行登记的双生子, 纳入≥18岁具有高血压患病信息的69 220名(34 610对)双生子进行分析。采用随机效应模型描述双生子中高血压患病的人群、地区分布特征。比较不同卵型间双生子的高血压同病率, 估算遗传度。结果研究对象年龄为(34.1±12.4)岁。双生子人群高血压报告患病率为3.8%(2 610/69 220)。年长、居住于城镇、已婚、超重或肥胖者、当前吸烟或曾经吸烟、当前饮酒或曾经饮酒人群中高血压报告患病率更高(P<0.05)。同性别双生子对内分析发现, 同卵双生子高血压同病率(43.2%)高于异卵双生子(27.0%), 差异有统计学意义(P<0.001), 高血压遗传度为22.1%(95%CI:16.3%～28.0%)。在不同性别、年龄、地区分层中, 同卵双生子高血压同病率大于异卵双生子, 在女性人群中, 高血压的遗传度更高。结论本研究中双生子人群的高血压分布存在人群...     

中国9省(市)成年双生子体重指数遗传度估计

目的 探讨中国9省(市)成年双生子BMI遗传度情况。方法 收集中国双生子登记系统9省(市)成年双生子信息, 采用结构方程模型计算11 122对双生子BMI遗传度。结果研究对象中同卵双生子6 226对, 异卵双生子4 896对, 年龄范围25～85(39.0±10.8)岁。按地区分层, 男性BMI遗传度最高的是天津, 为67.8%(95%CI:50.1%～85.8%), 最低的是浙江, 为42.1%(95%CI:27.2%～60.9%);女性最高的是四川, 为56.2%(95%CI:47.5%～70.0%), 最低的是黑龙江, 为11.2%(95%CI:0～31.7%)。按性别分层, 相同地区的男性BMI遗传度均高于女性, 其中黑龙江男性和女性的遗传度差异最大, 分别为55.3%(95%CI:35.5%～80.0%)和11.2%(95%CI:0～31.7%), 而四川男性和女性的遗传度差异最小, 分别为61.5%(95%CI:40.7%～86.4%)和56.2%(95%CI:47.5%～70.0%)。结论 中国不同地区和不同性别人群BMI遗传度存在差别。     

中国成年双生子人群冠心病分布特征

目的:描述中国双生子登记系统（CNTR）成年双生子冠心病的分布特征,探索我国双生子人群中冠心病的分布规律,为遗传和环境对于冠心病的作用提供线索和依据。方法:基于2010-2018年在CNTR进行登记的双生子,纳入≥18岁34 583对双生子进行分析,描述冠心病的人群、地区分布特征,分别计算同卵双生子（MZ）和异卵双生子...     

7~16岁儿童青少年肥胖与DNA甲基化相关性的双生子研究

目的 基于肥胖不一致双生子人群,在全基因组范围内探索与儿童青少年肥胖相关的DNA甲基化位点。方法 2016年在北京市朝阳区、延庆区及房山区招募90对6~17周岁双生子,通过问卷调查和体格检查收集双生子个人信息以及身高、体重、腰围等;通过美国Illumina公司EPIC芯片进行全基因组甲基化检测,采用R 3.3.1软件进行DNA甲基化数据读取、质量控制和统计学分析。利用肥胖不一致同卵双生子对,采用经验贝叶斯配对调整t检验和Levene检验,分别探索与肥胖相关的DNA甲基化差异位点和DNA甲基化变异差异位点。结果 根据研究定义,共纳入23对肥胖不一致同卵双生子对,年龄范围7~16岁。共有817 471个合格CpG位点纳入全基因组相关分析,未发现满足多重校正标准的肥胖相关DNA甲基化阳性位点,P值最小的DNA甲基化差异位点为12号染色体上的位点cg05684382（P=1.26E-06,FDR>0.05）,P值最小的DNA甲基化变异差异位点为16号染色体CMIP基因主体上的位点cg26188191（P=6.44E-06,FDR>0.05）,均为EPIC芯片新增位点。结论 基于本研究人群,研究未发现满足显著性要求的肥胖相关DNA甲基化阳性位点,但分析提示cg05684382、cg26188191可能与肥胖发生相关。     

2018年中国成年居民血压检测情况分析

目的 分析2018年我国成年居民血压检测情况,为高血压早期发现和干预提供科学依据。方法 2018年中国慢性病及危险因素监测在全国31个省（自治区、直辖市）的298个县（区）,采用多阶段分层整群随机抽样方法对≥18岁常住居民进行调查,有效样本量为184 509名,以面对面问卷调查和身体测量方法收集调查对象的人口学资料、主要慢性病与血压检测情况等信息,血糖和血脂相关指标由实验室检测获得。本研究剔除关键变量的异常和缺失数据后,共纳入170 551名成年居民作为研究对象。经复杂加权后分析不同血压水平和患其他疾病人群的血压检测率和检测时间分布情况。采用SAS 9.4软件进行χ²检验和趋势性检验。结果 我国成年居民中,正常血压人群、正常高值血压人群和新检出高血压的人群3个月内检测过血压的比例分别为44.4%、50.4%和52.6%,均为女性高于男性（均P<0.05）,城市高于农村（均P<0.05）,且随年龄增长呈上升趋势（均P<0.001）;3个人群中从未测过血压的比例分别为27.6%、24.2%、23.5%。已诊断高血压人群在7 d内检测过血压的比例为44.0%,城市为51.4%,高于农村的37.7%（P<0.001）,检测过血压的比例随文化程度、人均年收入和BMI增长而上升（均P<0.001）。结论 我国成年居民定期自我检测血压的行为还有待提高,尤其是男性和农村地区。应加强相关健康宣传教育,制定更有针对性的政策和措施,重点提高正常高值血压人群和其他高危人群的血压检测行为,有效预防和控制血压升高。     

Concordance for mortality with special reference to ischaemic heart disease and cerebrovascular disease: A Study on the Swedish Twin Registry

The Swedish Twin Registry contains about 11 000 same-sexed twin pairs born between 1886 and 1925 with both members alive when the registry was formed in 1961. During the years 1962 to 1973, 2780 deaths occurred. 727 deaths were due to ischaemic heart disease (IHD), 345 due to cerebrovascular disease (CVD), and 727 due to cancer. The rate of concordance for the whole twin population revealed a significantly (p < 0.05) higher concordance rate for IHD among the male monozygotic (MZ) pairs as compared to the dizygotic (DZ) pairs (15.8% versus 8.0%). The corresponding figures for the female pairs were 11.0% (MZ) and 7.5% (DZ), respectively. With regard to death in CVD and cancer, the rates of concordance were about the same for MZ and DZ pairs in both males and females. When subgrouping was made for age groups, the difference in concordance rate for IHD in males was still more pronounced for the younger age group, born 1901–1925, (16.1% versus 5.4%). These data may indicate the existence of a genetic determination on death in IHD, especially in males, whereas a genetic determination on death in CVD and cancer seems more uncertain.     

The epidemiology of anencephaly and spina bifida in Izmir, Turkey, in the light of recent aetiological theories

The data from this study suggest that, in western Turkey, potato consumption and water hardness do not play a significant role in the aetiology of anencephaly and spina bifida (ASB). Several of the predictions of the fetus-fetus interaction theory are not supported. Other predictions could not be tested because of lack of information on the dizygotic (DZ) twinning rate. Twin data from this study, together with previous material containing explicit information on zygosity, suggest that true concordance of a particular neural tube anomaly occurs only in monozygotic (MZ) twins. It also seems that even ASB concordance occurs in DZ twins only at a rate comparable with recurrence in siblings. This confirms the earlier refutation (Field and Kerr, 1974) of the supposition of Nance (1971) that MZ twin pairs are strikingly discordant for ASB compared with DZ pairs. However, the evidence seems to go further than Field's assertion that MZ and DZ pairs are affected about equally. Concordance in DZ twins is in comparison with sibling data, but MZ pairs show a significantly higher rate of concordance in both categories. Finally, the incidence of ASB in Izmir compared with the areas of ethnic origin of the Turks, and the high representation of families from Balkan areas where the incidence more closely resembles that of Izmir, suggest that the genetic factor is important in this area.     

Twins, smoking and mortality: a 12-year prospective study of smoking-discordant twin pairs

Despite the increasing scientific evidence for a causal role of tobacco smoking in lung cancer and coronary heart disease, critics, several decades ago, put forward an alternative hypothesis. The constitutional hypothesis has stated that there are genetic or other common factors, which predispose both to smoking and disease, but that the two are not causally related. A critical test of this hypothesis is the study of disease in monozygotic (MZ) twin pairs in which one smokes and the other never has. Earlier twin studies found only small differences in the mortality of smoking and nonsmoking twins of discordant pairs. In the Finnish Twin Cohort, a population-based panel of adult like-sexed twin pairs, a questionnaire study carried in 1975 permitted identification of twin pairs discordant for cigarette smoking. The nonsmoking cotwins had never been regular smokers. The smoking twins were divided into 1278 current smokers [CS; 143 MZ and 598 dizygotic (DZ) males and 171 MZ and 585 DZ females] and 1210 former smokers (FS; 129 MZ and 408 DZ males and 113 MZ and 341 DZ females). Exposure to tobacco was much higher among males; over 25% of men smoked 20 or more cigarettes daily compared to less than 10% of women. Follow-up of mortality yielded data on time and cause of death. Analyzing on first deaths from concordant pairs, there were 13 deaths in the smokers of male CS MZ pairs and 1 death in the nonsmoking cotwins (relative risk = 13.0, P less than 0.01). Excess mortality was also found for male CS DZ smokers (RR = 2.43, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Likelihood-based concordance tests for analysis of ascertained twin pair multinomial data

The classic twin model design has a wide application in human genetics. Under the assumption that nongenetic effects are shared to the same degree by monozygotic (MZ) and dizygotic (DZ) twin pairs, a test of the equality of casewise concordances between MZ and DZ twins provides a clue to the influence of genetic and environmental factors on a disease. The casewise concordance is the conditional probability that given that one member of a twin pair is affected, the other is also affected. When disease prevalence is low or cost-effectiveness is considered, collection of twin pairs by ascertainment for performing casewise concordance analysis is required. In this article, by defining an overall casewise concordance parameter, several likelihood-based tests, such as likelihood ratio test LR, score test Score, the usual Wald test Wald and an alternative Wald test WaldA are investigated for a test of the equality of concordances between ascertained MZ and DZ twin pairs under multinomial models. Simulation studies were conducted for data with small sample sizes. The results show that the type I error rates and power of LR and Score are stable only when the overall casewise concordances are not extremely small or large. The Wald has higher power performance in most cases but would slightly inflate type I error rates; the WaldA is the most robust and recommended approach.     

Heritability estimate for refractive errors--a population-based sample of adult twins

The population-based Finnish Twin Cohort study was used to establish a heritability estimate for refractive errors especially for myopia. The twin cohort was derived from adult same-sexed twins in Finland. The total number of twins with both members alive in 1984 was 23,570. Of these, 3,676 twin pairs were monozygotic, and 8,109 pairs dizygotic. The sample for the present study was linked from the Finnish Police Force data base in 1984, where information of a person's possession of a driver's license and the obligation to wear glasses for far correction when driving a motor vehicle is recorded. Correlations in liability were estimated according to a multifactorial method of Smith. Falconer's heritability was 0.62 among males and 0.98 among females in the age group 28-29 years. When compared to previous twin studies of myopia, the proband concordance rates were higher for both MZ and DZ twin pairs.     

Lifestyle factors in monozygotic and dizygotic twins

In examining genetic influences on biological variables using twins, it may be important to examine the distribution between and within twin pairs of demographic and lifestyle factors that may themselves affect the biological variable being studied. We explored the distribution of demographic and lifestyle factors that may affect blood lipid levels or ischaemic heart disease (IHD) risk among a sample of 106 monozygotic (MZ) and 94 like-sex dizygotic (DZ) twin pairs. In our sample, MZ twins were statistically significantly different from DZ twins only in marital status, cigarette smoking habits, and the ratio of polyunsaturated to saturated fat (P:S ratio) in their dietary intake. The latter variable was among many dietary variables examined (using 4-day weighed food diaries), and the size of the difference in intake was small. When comparisons were made of the similarities within twin pairs, we found members of MZ twin pairs to be statistically significantly closer than DZ twins in educational achievement, occupation, cigarette smoking, and exercise habits, and the number of days a week on which alcohol was consumed. These last three variables were consistently closer among twins with closer contact than among those with a smaller degree of current shared environment. For 12 of the 13 nutrients examined, the within-pair correlations were higher for MZ than for DZ twins, although our test for significant genetic variance showed statistical significance only for intake of complex carbohydrates. We conclude that MZ twins share demographic and lifestyle factors that might influence the risk of IHD and blood lipid levels to a greater degree than do DZ twins, although it is difficult to say if these similarities in lifestyle result from genetic influences or not. Nevertheless, ascribing differences between correlations in MZ and DZ twin pairs for lipid levels as being purely "genetic"--as implicit in conventional measures of heritability--is likely to overestimate the influence of genetic factors.     

Comparison of analysis of variance and maximum likelihood based path analysis of twin data: Partitioning genetic and environmental sources of covariance

In order to investigate currently used model fitting strategies for twin data, analysis of variance (ANOVA) and path-maximum-likelihood (PATH-ML) methods of analyzing twin data were compared using simulation studies of 50 monozygotic (MZ) and 50 dizygotic (DZ) twin pairs. Phenotypic covariance was partitioned into additive genetic effects (A), environmental effects common to cotwins (C), and environmental variance unique to individuals (E). ANOVA and PATH-ML had identical power to detect total covariance. The PATH-ML AE model was much more powerful than ANOVA comparisons of rMZ and rDZ to detect A. However, to be unbiased, the AE model requires the assumption that C = 0.0. To allow use of the AE model to estimate A, the null hypothesis C = 0.0 is tested by comparing the goodness of fit of the ACE and AE models. Simulation of 50 MZ and 50 DZ pairs revealed that C must be greater than 55% of total variance before the null hypothesis would be rejected (P < 0.05) 80% of the time. Several recent publications were reviewed in which the null hypothesis C = 0.0 was accepted and apparently upwardly biased estimates of A, containing C, were presented with unrealistic P values. It was concluded that use of the AE model to estimate A gives an inflated view of the power of relatively small twin studies. It was recommended that ANOVA or comparison of the ACE and CE PATH-ML models be used to estimate and test the significance of A as neither requires that C = 0.0. © Wiley-Liss, Inc.     

双生子A型人格与高血压及血生化指标研究

目的 了解双生子A型人格与高血压及血液生化指标的关系。方法 利用遗传流行病学方法对青岛市89对24岁以上双生子(同卵55对，异卵34对)进行调查。并进行A型人格测试，以比较同卵与异卵双生于A型人格得分的相关程度、A型人格及血压的一致性。推测遗传与环境因素对A型人格的影响，A型人格与高血压的关系，并探讨血液生化指标与A型人格的关系。结果 经KAPPA一致性检验，同卵(MZ)双生子之间A型人格存在着显的一致性(P＜0．001)，而异卵(DZ)双生子之间的一致性无显性差异(P＝0．802)。同时，MZ双生子之间A型人格和血压也存在显的一致性(P＜0．001)，而DZ双生子之间A型人格和血压无明显一致性(P＝0．102)。有A型人格的双生子血压的收缩压明显高于非A型人格的双生子(P＜0．05)。许多生化指标与A型人格因素相关，但是所计算出的相关系数大都小于0．30，属于弱相关。结论 MZ双生子A型人格及高血压之间存在着显的一致性，而这种一致性在DZ双生子表现不明显。A型人格是高血压的危险因素之一。A型人格与所研究血液基本生化指标之间相关较弱。