Differences in Nutritional Intake,Total Body Fat,and BMI Score between Twins

The present study aimed to investigate the coincidence of obesity and nutritional intake in monozygotic twins compared to dizygotic twins. The data from the Korean Genome and Epidemiology Study (KoGES) from 2005 through 2014 were analyzed. Participants ≥ 20 years old were enrolled. The 1006 monozygotic twins and 238 dizygotic twins were analyzed for differences in self-reported nutritional intake, total body fat, and body mass index (BMI) using a linear regression model. The estimated values (EV) with 95% confidence intervals (95% CI) of the difference in dietary intake, total body fat, and BMI score were calculated. The monozygotic twin group and the dizygotic twin group showed similar differences in nutritional intake, DEXA fat, and BMI (all p > 0.05). The differences in nutritional intake of total calories and carbohydrates were lower in the monozygotic twin group than in the dizygotic twin group (all p < 0.05). The differences in total body fat were lower in monozygotic twins than in dizygotic twins (adjusted EV = 2427.86 g, 95% CI = 1777.19–3078.53 and adjusted EV = 1.90%, 95% CI = 1.33–2.46). Monozygotic twins had more similar dietary habits for total calories and carbohydrate intake. Other nutritional factors did not show differential similarity between monozygotic and dizygotic twins. Total body fat was more concordant in monozygotic twins.     

Comparison of the Coincidence of Osteoporosis,Fracture, Arthritis Histories,and DEXA T-Score between Monozygotic and Dizygotic Twins: A Cross-Sectional Study Using KoGES HTS Data

We explored the genetic and environmental inter-relationships among osteoporosis, fracture, arthritis, and bone mineral density concordance in monozygotic twins compared to those in dizygotic twins. This cross-sectional research assessed data of 1032 monozygotic and 242 dizygotic twin pairs aged >20 years included in the Healthy Twin Study data of the Korean Genome and Epidemiology Study between 2005 and 2014. Outcomes of interest included illness concordance and absolute differences in dual-energy X-ray absorptiometry (DEXA) T-scores. We found comparable concordances of osteoporosis, fractures, osteoarthritis, and rheumatoid arthritis between monozygotic and dizygotic twins. Medical histories of osteoporosis, fractures caused by accident or falling, osteoarthritis, and rheumatoid arthritis were not distinct between monozygotic and dizygotic twins. Accidental fracture occurrence in both monozygotic twins showed significantly lower odds than that in dizygotic twins. Genetic influence on liability to fracture risk might thus be maintained. DEXA T-scores for bone mineral density indicated more comparable tendencies within monozygotic twin pairs than within dizygotic ones, suggesting the relative importance of genetic contribution to bone mineral density. The relative importance of genetic factors in bone mineral density is sustained between monozygotic twins; overt disease expression of osteoporosis, fractures, or arthritis may be affected by environmental factors.     

Handedness and mortality: a follow-up study of Danish twins born between 1900 and 1910

The declining prevalence of left-handed individuals with increasing age has led to two main avenues of hypotheses; the association is due either (1) to a birth cohort effect and/or an age effect caused by a switch to right-handedness with advancing age or (2) to mortality selection that reduces survival in left-handed individuals, or both. It is uncertain whether a cohort or age effect can explain the decline in age-related prevalence, and conflicting evidence exists in favor of the mortality hypothesis. We compared mortality in a subgroup of 118 opposite-handed twin pairs by counting in how many instances the right-handed twin died first. There was no evidence of differential survival between right-handed and non-right-handed individuals in the entire 1900-1910 cohort. With respect to the number of right-handed twins who died first, there was no material disadvantage among those who were not right-handed. In 60% (95% confidence interval = 49.0-71.5%) of dizygotic pairs, the right-handed twins died first. In 50% of monozygotic pairs, right-handed twins died first. The prevalence of not being right-handed was higher among males (9.2%) than females (6.5%); there was a similar frequency of non-right-handedness in monozygotic (8.0%) and dizygotic (7.8%) twins. We did not find evidence of excess mortality among non-right-handed adult twins in this follow-up study.     

Contribution of genetic and environmental influences to ankle-brachial blood pressure index in the NHLBI Twin Study. National Heart, Lung, and Blood Institute

The ankle-brachial index (ABI) is widely used in the clinical diagnosis of peripheral arterial disease. The contributions of genetic and environmental influences to normal and abnormal ABI values are unknown. In this study, the authors used available data on 94 monozygotic pairs and 90 dizygotic pairs of elderly, White, male twins examined in 1995-1997 to investigate the contributions of genetic and environmental influences to normative ABI values. Within-twin-pair correlations for normative ABI values were statistically significant, and the correlation in monozygotic twin pairs was significantly greater than that in dizygotic pairs. Structural equation modeling of the variance-covariance matrices of monozygotic and dizygotic twins indicated that 48% of the observed variability in ABI values could be attributed to additive genetic effects. In contrast, concordance rates for low ABI values (ABI< or =0.9) for both monozygotic and dizygotic twins were significantly greater than would be expected by chance alone, but within-pair monozygotic similarity was not significantly greater than dizygotic similarity. A matched-cotwin analysis in 21 pairs that were discordant for low ABI values found that twins with low ABI values were physically less active and more likely to be persistent smokers than their normal-control brothers. These findings reinforce the role of individual health practices (e.g., physical activity, smoking) in the manifestation of peripheral arterial disease among subjects matched for age, genetics, and early shared environment.     

Concordance for bulimia nervosa in twins

27 pairs of twins with bulimia nervosa according to DSM-III-R were assessed concerning concordance for bulimia nervosa and other eating disorders. There were 6 monozygotic females, 1 monozygotic male, 15 dizygotic females and 5 dizygotic twins of opposite sex. The concordance rates for bulimia nervosa (83.3 versus 26.7%) and for any eating disorder according to DSM-III-R (83.3 versus 33.3%) were significantly higher for monozygotic, as compared to dizygotic females. 27 (54%) of 50 twins had a diagnosis of depression according to ICD-9 criteria, with a small difference between monozygotic (60%) and dizygotic (53%) twins of the same sex. According to our data, monozygotic bulimic twins appear to have an increased genetic-biological vulnerability for a mental or eating disorder. Possible effects of disturbances in the process of individuation and in the development of an autonomous self due to social consequences of their physical identity with the cotwin are discussed.     

Comparison of the Concordance of Cardiometabolic Diseases and Physical and Laboratory Examination Findings between Monozygotic and Dizygotic Korean Adult Twins: A Cross-Sectional Study Using KoGES HTS Data

This study investigated the contribution of genetic and environmental factors to cardiometabolic diseases (CMDs) by comparing disease concordance in monozygotic and dizygotic twins. This cross-sectional study analyzed 1294 (1040 monozygotic and 254 dizygotic) twin pairs (>20 years) based on the Korean Genome and Epidemiology Study data (2005–2014). The odds ratios of disease concordance were calculated using binomial and multinomial logistic regression models. The occurrence of CMDs (hypertension, hyperlipidemia, type 2 diabetes, cerebral stroke, transient ischemic attack, and ischemic heart disease) and related physical and laboratory levels did not differ between the monozygotic and dizygotic twin groups. The odds for concordance of the presence/absence of CMDs and the likelihood of incident CMD within monozygotic twins were comparable to that of dizygotic twins. The absolute differences in hemoglobin A1c, insulin, low- and high-density lipoprotein cholesterol, total cholesterol, triglycerides, and systolic blood pressure were lower in monozygotic twins than in dizygotic twins. Absolute differences in fasting glucose and diastolic blood pressure did not differ between groups. Although baseline levels of several laboratory parameters related to CMD showed a strong likelihood of heritability in monozygotic twins, CMD phenotype appears to be largely affected by environmental factors.     

Genetic and developmental influences on susceptibility to epilepsy: evidence from twins

This study evaluated genetic and developmental contributions to epilepsy, using data on epilepsy and multiple births in the sibships of 1981 probands with epilepsy. Prevalence of a history of epilepsy was much higher in monozygotic (MZ) than in dizygotic (DZ) co-twins of probands (35.0% vs. 3.7%), but prevalence was not significantly higher in DZ co-twins than in singleton siblings. The proportion of individuals who were MZ twins was higher among probands with epilepsy than among their non-co-twin siblings without epilepsy (odds ratio 2.5, 95% CI 1.31-4.85). However, the proportion who were DZ twins was similar among probands and unaffected siblings (odds ratio 1.0, 95% CI 0.67-1.60). These findings suggest that the increased prevalence of epilepsy in MZ co-twins of probands may be partly explained by developmental factors related to MZ twinning, rather than by their genetic identity with the probands.     

Genetic effects on weight change and food intake in Swedish adult twins

BACKGROUND: Obesity is influenced by genetic and environmental factors. Additionally, synergistic effects of genes and environments may be important in the development of obesity. OBJECTIVE: The aim of this study was to test for genetic effects on food consumption frequency, food preferences, and their interaction with subsequent weight gain. DESIGN: Complete data on the frequencies of consumption of 11 foods typical of the Swedish diet were available for 98 monozygotic and 176 dizygotic twin pairs aged 25-59 y who are part of the Swedish Twin Registry. The data were collected in 1973 as part of a questionnaire study. Body mass index was measured in 1973 and again in 1984. RESULTS: There was some evidence that genetic effects influenced the frequency of intake of some foods. Similarity among monozygotic twins exceeded that among dizygotic twins for intake of flour and grain products and fruit in men and women, intake of milk in men, and intake of vegetables and rice in women, suggesting that genes influence preferences for these foods. Analyses conducted for twins reared together and apart also suggested greater monozygotic than dizygotic correlations, but cross-twin, cross-trait correlations were all insignificant, suggesting that the genes that affect consumption frequencies are not responsible for mediating the relation between the frequency of intake and weight change. CONCLUSIONS: Genetic effects and the frequency of intake are independently related to change in body mass index. However, there was no suggestion of differential genetic effects on weight gain that were dependent on the consumption frequency of the foods studied.     

The correlation of fecundability among twins: evidence of a genetic effect on fertility?

BACKGROUND: Numerous rare genetic conditions are known to influence fecundability in both males and females. It is less clear to what extent more subtle genetic differences influence fecundability on a population level. METHODS: In 1994 a population-based survey was conducted among Danish twins born 1953-1982. Fecundability was assessed as the waiting time to pregnancy at the first attempt to achieve a pregnancy. RESULTS: The reported time to pregnancy for males was slightly shorter than for females but there were no sex differences in intrapair similarity. We found an intrapair correlation in time to pregnancy for 645 monozygotic twin pairs (r = 0.22; 95% confidence interval = 0.12 to 0.32), but no intrapair correlation for 826 like-sex dizygotic twin pairs (r = 0.00; 95% confidence interval = -0.09 to 0.10). CONCLUSIONS: The correlation in time to pregnancy for monozygotic twins suggests genetic factors, although similarities in reporting behaviors could also be contributing to the correlation. The lack of correlation in time to pregnancy for dizygotic twins indicates that possible genetic factors of importance for fecundabililty are acting nonadditively. Hence, it may prove difficult to identify specific gene variants that influence fecundability on a population level if their effects depend on gene-gene interactions.     

The role of genetic and environmental factors in the association between birthweight and blood pressure: evidence from meta-analysis of twin studies

BACKGROUND: An inverse association between birthweight and later blood pressure has been found in many studies in singletons. Twin studies have been used to examine whether genetic factors or family environment could account for this association. METHODS: A systematic review identified 10 studies covering 3901 twin pairs. Meta-analysis of regression coefficients for the association between birthweight and systolic blood pressure was carried out for unpaired versus paired associations and for paired associations in dizygotic versus monozygotic pairs. RESULTS: After adjustment for current weight or body mass index (BMI), the difference in systolic blood pressure per kg birthweight was -2.0 (95% CI: -3.2, -0.8) mmHg in the unpaired analysis and -0.4 (95% CI: -1.5, 0.7) mmHg in the paired analysis in the same subjects. In the paired analysis by zygosity, in all twins the coefficients were -0.7 (95% CI: -2.3, 0.8) mmHg in dizygotic pairs and -0.8 (95% CI: -2.1, 0.4) mmHg in monozygotic pairs, but in studies which included zygosity tests the coefficients were -1.0 (95% CI: -3.3, 1.6) mmHg in dizygotic pairs and -0.4 (95% CI: -1.9, 1.3) mmHg in monozygotic pairs. CONCLUSIONS: The attenuation of the regression coefficient in the paired analysis provides support for the possibility that factors shared by twins contribute to the association between birthweight and blood pressure in singletons. Comparison of paired analysis in monozygotic and dizygotic pairs could not provide conclusive evidence for a role for genetic as opposed to shared environmental factors.     

Homosexual orientation in twins: A report on 61 pairs and three triplet sets

Twin pairs in which at least one twin is homosexual were solicited through announcements in the gay press and personal referrals from 1980 to the present. An 18-page questionnaire on the sexuality of twins was filled out by one or both twins. Thirty-eight pairs of monozygotic twins (34 male pairs and 4 female pairs) were found to have a concordance rate of 65.8% for homosexual orientation. Twenty-three pairs of dizygotic twins were found to have a concordance rate of 30.4% for homosexual orientation. In addition, three sets of triplets were obtained. Two sets contained a pair of monozygotic twins concordant for sexual orientation with the third triplet dizygotic and discordant for homosexual orientation. A third triplet set was monozygotic with all three concordant for homosexual orientation. These findings are interpreted as supporting the argument for a biological basis in sexual orientation.     

成年双生子血尿酸遗传度研究

目的 用双生子研究方法 对成年人血尿酸的遗传度进行估计.方法 从青岛双生子库募集成年双生子.测量身高、体重和血尿酸.相同性别的双生子采用16个多态标记进行卵型鉴定.通过校正年龄、性别和BMI,来构建结构方程模型估计遗传度.结果 共收集687对双生子数据,其中同卵双生子420对,异卵双生子267对.经平方根转换后,男性血尿酸水平(17.47±1.91)略高于女性(15.22±1.70)(P＜0.0001),通过校正年龄、性别和BMI后双生子血尿酸的组内相关系数分别为,同卵双生子0.70、异卵双生子0.40.运用性别限制模型进行拟合,最佳模型AE模型,加性别遗传因素和特殊环境因素共同作用血尿酸的水平.血尿酸的遗传度为70.5%(95%CI:65.9～74.6),特殊环境因素占29.5%(95%CI:25.4～34.2).结论 遗传因素是影响样本双生子血尿酸水平的主要因素.     

Major genetic susceptibility for venous thromboembolism in men: a study of Danish twins

BACKGROUND: Although several genetic determinants (mutations or polymorphisms) have been associated with increased risk of venous thromboembolism, the overall influence of genetic factors on this disease is unknown. METHODS: We linked the Danish Twin Registry, which includes twins born 1870-1953, with the Danish National Registry of Patients, comprising all hospitalizations in Denmark since 1977. We then determined the risk of venous thromboembolism as determined from discharge diagnosis. RESULTS: We identified 26,982 twins who were alive on 1 January 1977, and computed measures of familial and genetic association of venous thrombotic disorders. Individuals were classified according to zygosity and hospitalization with venous thromboembolism. Since 1977, 678 twins were hospitalized with an episode of venous thromboembolism. Of these, only 545 pairs (281 male pairs and 264 female pairs) were alive in 1977. For men, the concordance rates for mono- and dizygotic twin pairs, respectively, were 0.22 (95% confidence interval = 0.14 to 0.30) and 0.08 (0.04-0.12). The odds ratio (interpreted as the relative risk of venous thromboembolism for one twin, given venous thromboembolism in the partner twin) was 13.5 (7.3-24.8) among monozygotic twins and 3.8 (1.8-8.3) among dizygotic twins. The respective correlations for venous thromboembolism were 0.55 (0.38-0.70) and 0.26 (0.09-0.42). The proportion of the variance attributable to genetic effects on venous thromboembolism in males was 55% (39%-68%). The remaining variation could be attributed to men's nonfamilial environments. In contrast, for women there was no intra-twin pair similarity for venous thromboembolism. CONCLUSIONS: We found differences in genetic susceptibility to venous thromboembolism between the sexes, with genetic factors playing a substantially stronger role in males than in females.     

Genetic and environmental influences on the tracking of body size from birth to early adulthood

OBJECTIVE: This study identified genetic and environmental influences on the tracking of body size from birth to 16 to 18.5 years of age. RESEARCH METHODS AND PROCEDURES: Longitudinal information was collected from a nationally representative sample of Finnish twin adolescents (birth cohorts 1975 to 1979) and their parents through questionnaires mailed when the twins were ages 16 and 18.5 years old. The sample included 702 monozygotic, 724 same-sex dizygotic, and 762 opposite-sex dizygotic sets of twins. The measures used were length, weight, ponderal index (kilograms per cubic meters), and gestational age at birth, and height, weight, and body mass index (kilograms per square meters) at 16 to 18.5 years of age. The changes in genetic and environmental influences on body size from birth to early adulthood were analyzed by quantitative genetic modeling. RESULTS: The twins who had a higher weight or ponderal index at birth were taller and heavier in early adulthood, whereas those who were longer at birth were taller, but not heavier, later in life. Adult height was affected more by the birth size than body mass index. In the genetic modeling analyses, the genetic factors accounting for the variation of body size became more apparent with age, and both genetic and environmental influences on stature had a sizable carry-over effect from birth to late adolescence, whereas for relative weight, the influences were more age-specific. DISCUSSION: The genetic and environmental architecture of body size changes from birth to adulthood. Even in monozygotic twins who share their genetic background, the initially larger twin tended to remain larger, demonstrating the long-lasting effects of fetal environment on final body size.     

Comparative study of the consumption of cariogenic food in monozygotic and same-sex dizygotic twins

The eating habits of the 111 monozygotic and 67 like-sexed dizygotic twins were compared with respect to cariogenic foods. The food habits were recorded using a seven-day dietary history with the weekly frequency of the cariogenic foods examined. The biometrical analysis showed that the eating habits of the monozygotic pairs were more similar than that of the dizygotic twin pairs. The differences were statistically significant. Based on these findings, it seems that genetic factors play a role in the development of the food habits.     

58对孤独症谱系障碍双胞胎临床特点及同病率分析

目的 分析58对孤独症谱系障碍(ASD)双胞胎临床特点及同病率,以及其遗传规律和影响因素。方法 收集1999-2015年就诊于中山大学附属第三医院发育行为中心的ASD双胞胎,对随访的58对ASD双胞胎临床资料进行总结分析,其中至少1名双胞胎诊断为ASD,通过统计描述,使用R软件进行分析同病率。结果 双胞胎出生体重较低,胎龄较小,围生期有较多高危因素;同卵双胞胎的同病率为73.68%,异卵双胞胎的同病率为12.82%,差异具有统计学意义(χ²＝18.81,P<0.001)。结论 ASD双胞胎同卵双胞胎具有较高的同病率,提示遗传因素是其重要病因。     

The graphical representation of the self-image in early development: twins and singletons in comparison

The construction of self, a fundamental process for development. Twins, as they grow together, may encounter greater difficulties in individuation process. The present study aims to investigate the construction of the image of the self and of the self with its own twin/sibling through the drawing of the human figure and to highlight any differences in these representations between monozygotic twins, dizygotic twins, and non-twins. A sample of 105 children aged between 4 and 6 years participated in the research. From the analysis of the drawings of the self and of the self with the sibling, differences in self-representation and representation with the sibling have emerged and can be understood in the light of the separation and individuation process that characterizes the development of the self-image. In particular, greater tendencies have emerged for monozygotic twins to represent themselves differently from the co-twin and for dizygotic twins to show identical figures.     

双生子儿童贫血状况分析

目的通过分析双生子儿童贫血状况和贫血同病率,探讨其遗传和环境效应.方法选取5～19岁双生子228对,其中MZ(单卵双生子)142对,DZ(二卵双生子)86对,在DNA卵性鉴定基础上,以成对法计算同病一致率、调整BMI前后组内相关系数及遗传度.结果双生子儿童贫血检出率与一般人群无明显差异,贫血同病一致率分别为MZ 0.28,DZ 0.15,Hb(血红蛋白)遗传度为0.23.调整BMI前后MZ与DZ组内相关系数和遗传度无显著变化.结论儿童贫血状态受遗传及环境因素共同影响,环境效应更明显.     

Twins with Coal-workers'' Pneumoconiosis

As the tuberculous hypothesis of coal-workers' progressive massive fibrosis (P.M.F.) is not so strongly held nowadays the possible importance of genetic factors should be explored. Twins with pneumoconiosis should provide helpful information. Details are given of two pairs of twins; one pair is considered to be monozygotic and the other dizygotic. Blood grouping, secretor state, and Rose Waaler reactions were carried out as the results may help in any comparison with twins with coal-workers' pneumoconiosis discovered elsewhere.

The brothers resemble each other in having a similar type of pneumoconiosis. The monozygotic pair have a relatively benign type of pneumoconiosis with early P.M.F. which has remained unchanged for eight years; the dizygotic pair show a nodular type of pneumoconiosis which has shown definite progression with an increase in the extent of P.M.F. As a younger brother of the dizygotic pair also has pneumoconiosis details are included.

     

Is there an increased risk of twinning after discontinuation of the oral contraceptive pill?

We investigated whether conception soon after cessation of use of oral contraceptives affects the chance of bearing twins. Unpublished data from a large sample survey of contraceptive practice in Scotland were used to derive oral contraceptive discontinuation rates by month over the decade 1972-82 and these were related to estimated monozygotic and dizygotic twin birth rates and proportions by month in Scotland from 1974-82, using regression techniques. The results provide some support for the hypothesis that there is an increased risk of conceiving monozygotic twins within a year of ceasing to use oral contraceptives.