The establishment of the Brazilian Twin Registry for the study of genetic, social, and cultural influences on behavior is one of eleven newly funded projects in the Department of Psychology at the University of S ˜ao Paulo. These 11 interrelated projects form the core of the university’s Center for Applied Research on Well- Being and Human Behavior. An overview of the planned twin research and activities to date is presented. Next, two recent twin studies are reviewed, one on the relationship between alcohol consumption and mortality, and the other on factors affecting maximal oxygen uptake. Twins cited in the media include the first identified superfecundated twins in Vietnam, adolescent twin relations, twins and triplets who work together, monozygotic twins with different skin tones and a co-twin control study that addresses the effects of space travel.
The Brazilian Twin Registry (BTR) was established in 2013 and has impelled twin research in South America. The main aim of the initiative was to create a resource that would be accessible to the Brazilian scien- tific community as well as international researchers interested in the investigation of the contribution of genetic and environmental factors in the development of common diseases, phenotypes, and human be- havior traits. The BTR is a joint effort between academic and governmental institutions from Brazil and Australia. The collaboration includes the Federal University of Minas Gerais (UFMG) in Brazil, the University of Sydney and University of Melbourne in Australia, the Australian Twin Registry, as well as the research foundations CNPq and CAPES in Brazil. The BTR is a member of the International Network of Twin Reg- istries. Recruitment strategies used to register twins have been through participation in a longitudinal study investigating genetic and environmental factors for low back pain occurrence, and from a variety of sources including media campaigns and social networking. Currently, 291 twins are registered in the BTR, with data on demographics, zygosity, anthropometrics, and health history having been collected from 151 twins us- ing a standardized self-reported questionnaire. Future BTR plans include the registration of thousands of Brazilian twins identified from different sources and collaborate nationally and internationally with other research groups interested on twin studies.
The Norwegian Twin Registry (NTR) was established in 2009 as a merger of three major population-based Norwe- gian Twin Panels (Bergem, 2002; Harris et al., 2002, 2006). The NTR is housed at the Norwegian Institute of Public Health (NIPH), which currently runs 10 of Norway’s na- tional health registries and several large population-based cohort studies. The principal reasons for establishing the NTR are to promote research that exploits the value in- herent in twin designs and to create a resource for studies in genetic epidemiology. Therefore, the registry makes data accessible to researchers for a wide range of studies. The reg- istry infrastructure easily accommodates future expansions and enhancements of the twin data as described below. The purpose of this article is to describe the NTR today, in- cluding potentials for enriching the existing data through matches to other national registries and existing biological sample resources.
Since twins reared apart are quite rare, and because it is difficult to get access to a large sample size, there are only a limited number of studies in the literature. This makes the currently remaining study on twins reared apart particularly valuable. This kind of study has already been initiated in Sweden, Australia, the United States, and Japan (Hayakawa et al., 2006), but in terms of distribution of twins separated early, there have been few study reports as of the present time. China has a large twin population, and according to a study conducted by Gan and Zheng (2002), in 1989 alone, 186,273 pairs of twins were born, account- ing for 0.762% of newborns in the same year. Furthermore, Shandong, Henan, and Jiangsu were the top three provinces in China for twin birthrates, which were 1.391%, 1.066%, and 0.949%, respectively (Gan & Zheng, 2002). Due to the application of assisted reproductive technologies in recent years, the number of twins is expected to rise. Despite such rich twin resources in China, no study on twins reared apart has been fully conducted. In 2011, Peking Univer- sity analyzed a small number of twins reared apart in the Chinese National Twin Registry (CNTR) for a pilot study, discovering that three pairs of twins out of 505 pairs in Qingdao, Shandong, were reared apart and 27 pairs out of 503 in Lishui, Zhejiang, were reared apart, accounting for 0.6% and 5.4% respectively of the total (Gao et al., 2011). Given such a large range, the sample size needs to be further expanded to encompass a large area. Thus, the CNTR con- ducted a cross-sectional study in nine provinces or cities in China to understand the approximate distribution of twins reared apart.
Poor sleep quality is highly prevalent in patients with low back pain (LBP) and is associated with high levels of pain, psychological distress, and physical disability. Studies have reported a bidirectional relationship be- tween sleep problems and intensity of LBP. Accordingly, effective management of LBP should address sleep quality. In addition, genetics has been found to significantly affect the prevalence of both LBP and insom- nia. Our study aims to establish the feasibility of a trial exploring the efficacy of a web-based sleep quality intervention in people with LBP, with the genetic influences being controlled for. 30 twins (15 complete pairs) with subacute or chronic LBP ( > 6 weeks) will be recruited from the Australian Twin Registry. Partici- pants will be randomly assigned to one of the two groups with each twin within a pair receiving either an interactive web-based sleep intervention based on cognitive behavioral therapy principles (intervention) or a web-based education program (control) for 6 weeks. The feasibility of the trial will be investigated with regard to recruitment rate, feasibility of data collection and outcome measure completion, contami- nation of intervention, acceptability and experience of intervention, and sample size requirement for the full trial. Patient outcomes will be collected electronically at baseline, immediately post-treatment, and at 3-months’ follow-up post-randomization. This trial employs a robust design that will effectively control for the influence of genetics on treatment effect. Additionally, this study addresses sleep quality, a significant but under-explored issue in LBP. Results will inform the design and implementation of the definitive trial.
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This study is based on the data from the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins; Silventoinen et al., 2015). Briefly, the CODATwins project was launched in 2013 and was intended to recruit all twin projects in the world with information on zygosity and height and weight measurements. The present study included a total of 54 twin cohorts from 22 coun- tries: one cohort from Africa (Guinea-Bissau Twin Study), three cohorts from Australia (Australian Twin Registry, Peri/Postnatal Epigenetic Twins Study, and Queensland Twin Register), nine cohorts from East-Asia (Guangzhou Twin Eye Study, Japanese Twin Cohort, Korean Twin-Family Register, Mongolian Twin Registry, Osaka University Aged Twin Registry, South Korea Twin Registry, Qingdao Twin Registry of Adults, Qingdao Twin Registry of Children, and West Japan Twins and Higher Order Multiple Births Reg- istry), 22 cohorts from Europe (Adult Netherlands Twin Registry, Berlin Twin Register, Bielefeld Longitudinal Study of Adult Twins, Danish Twin Cohort, East Flanders Prospec- tive Twin Survey, Finnish Older Twin Cohort, FinnTwin12, FinnTwin16, Gemini Study, Genesis 12–19 Study, Hun-
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In the CODATwins database (Silventoinen et al., 2015), there are 960,859 height and weight measures from twins at ages ranging from 0.5 to 103 years. Information on birth order, height, and weight measures were self-reported (67%), parentally reported (19%), or based on measures by nurses and clinicians (14%). In this study, we in- cluded the following cohorts with information on birth order: Australian Twin Registry, Boston University Twin Project, Carolina African American Twin Study of Aging, FinnTwin12, FinnTwin16, Gemini Study, Guangzhou Twin Eye Study, Guinea-Bissau Twin Study, Hungarian Twin Reg- istry, Japanese Twin Cohort, Korean Twin-Family Regis- ter, Longitudinal Israeli Study of Twins, Michigan Twins Study, Murcia Twin Registry, Norwegian Twin Registry, Peri/Postnatal Epigenetic Twins Study, Qingdao Twin Reg- istry of Children, Quebec Newborn Twin Study, Queens- land Twin Register, Swedish Young Male Twins Study of Adults, Swedish Young Male Twins Study of Children, South Korea Twin Registry, Swedish Twin Cohorts, Twins Early Developmental Study, West Japan Twins and Higher Order Multiple Births Registry and Young Netherlands Twin Reg- istry. Height and weight measurement protocols, sample
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The different findings between studies that used the two approaches to data collection are illustrative. Median cor- relations across studies yielded correlations of 0.52 (MZ) and 0.17 (DZ) for studies using targeted sampling. In con- trast, the median correlations were 0.25 (MZ) and 0.13 (DZ) for studies using registry data. Heritability is decidedly less (0.32) when calculated from registry data. Interestingly, an Australian twin registry study by Kirk et al. (2000; not in- cluded in the Bailey et al., 2016 summary) reported heri- tabilities of 0.30 for male sexual orientation and between 0.50–0.60 for female sexual orientation. The 4,901 twins in this study answered an anonymous questionnaire, which may have increased the truthfulness of their responses. Note that the relatively higher heritabilities reported for fe- males than males in the Australian study are at odds with the more frequent findings of relatively higher male than fe- male heritability, such as those from a large registry-based Swedish investigation (males: 0.34–0.39; females: 0.18–19.) by Långström et al. (2010). Bailey et al. (2016) noted that calculating the degree of genetic and environmental effects on sexual orientation separately for males and females was precluded by the availability of too few registry samples. Such an analysis should be possible in the future, given the growing number of twin registries worldwide (Hur & Craig, 2013; Segal, 2016).
The extent to which genetic and environmental factors un- derlie atopic diseases has been debated for some time. Ac- cording to Danish researchers Kahr et al. (2014), twin stud- ies show that approximately 80% of the variation in atopic diseases is associated with genetic factors. They also pointed out that large epidemiological research on non-twins has linked environmental factors (e.g., socioeconomic status and parental smoking) to atopic disease in children. In or- der to address this issue, these investigators administered a questionnaire to parents of twin children enrolled in the Danish Twin Registry between 1994 and 2000. The reason- ing was that MZ twins with different early life environ- mental exposures (e.g., type of delivery and maternal age) might show differences in being affected by atopic disease. The final sample included data on 850 MZ and 2,279 DZ same-sex twin pairs, between 3 and 9 years of age. Questions were modified from those included in forms administered to participants in the International Study of Asthma and Allergies in Childhood.
Silventoinen is supported by Osaka University's International Joint Research Promotion Program. This research was facilitated through access to Twins Research Australia, a national resource supported by a Centre of Research Excellence Grant (ID: 1079102), from the National Health and Medical Research Council. The Boston University Twin Project is funded by grants (#R01 HD068435 #R01 MH062375) from the National Institutes of Health to K. Saudino. Paulo Ferreira is funded by a National Medical Research Council Research Fellowship. California Twin Program was supported by The California Tobacco-Related Disease Research Program (7RT-0134H, 8RT-0107H, 6RT-0354H) and the National Institutes of Health (1R01ESO15150-01). The Carolina African American Twin Study of Aging (CAATSA) was funded by a grant from the National Institute on Aging (grant 1RO1-AG13662-01A2) to K. E. Whitfield. The CATSS-Study is supported by the Swedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM) framework grant no 340-2013-5867, grants provided by the Stockholm County Council (ALF- projects), the Swedish Heart-Lung Foundation and the Swedish Asthma and Allergy Association’s Research Foundation. Chinese National Twin Registry is funded by Special Fund for Health Scientific Research in the Public Welfare (Project No: 201502006), China. Colorado Twin Registry is funded by NIDA funded center grant DA011015, & Longitudinal Twin Study HD10333; Author Huibregtse is supported by 5T32DA017637 and 5T32AG052371. Danish Twin Registry is supported by the National Program for Research Infrastructure 2007 from the Danish Agency for Science, Technology and Innovation, The Research Council for Health and Disease, the Velux Foundation and the US National Institute of Health (P01 AG08761). Since its origin the East Flanders Prospective Survey has been partly supported by grants from the Fund of Scientific Research, Flanders and Twins, a non-profit Association for Scientific Research in Multiple Births (Belgium). Data collection and analyses in Finnish twin cohorts have been supported by ENGAGE – European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, and AA-09203 to R J Rose, the Academy of Finland Center of Excellence in Complex Disease Genetics (grant numbers: 213506, 129680), and the Academy of Finland (grants 100499, 205585, 118555, 141054, 265240, 263278 and 264146 to J Kaprio). Gemini was supported by a grant from Cancer Research UK (C1418/A7974). Waves 1-3 of Genesis 12-19 were funded by the W T Grant Foundation, the University of London Central Research fund and a Medical Research Council Training Fellowship (G81/343) and Career Development Award (G120/635) to Thalia C. Eley. Wave 4 was supported by grants from the Economic and Social
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Recruitment for the present study was completed via the community-based Washington State Twin Registry (WSTR; previously known as the University of Washington Twin Registry). Complete details of the construction and current components of the WSTR are available elsewhere (Afari et al., 2006; Strachan et al., 2013). Briefly, recruitment into the WSTR itself relies on initial identification of twins from the Washington State Department of Licensing (DOL), which asks all driver license and state ID applicants: ‘Are you a twin (Y/N)?’ Based on a data-sharing agreement between DOL and the University, the names and contact informa- tion of all twin respondents are then sent to the WSTR. Twins are contacted with information about the Registry and an enrollment survey. After both members of the pair complete the survey, the pair is enrolled in the Registry. The Registry contacts the twins multiple times each year with birthday cards, newsletters, and study invitations in order to keep contact information current. At the time recruitment began, the average age of enrolled twins was 37, and 41% of the twins reported being married. Approximately 4% of the Registry reported being Hispanic and 86% reported be- ing White. All other racial categories were < 4%. In terms of educational achievement, 25% completed high school or GED, an additional 34% had some college/vocational school, and 33% had a bachelor’s degree or higher.
This is the first case to our knowledge to present posterior mitral valve cleft in monozygotic twins within a triplet pair, who are discordant regarding the mitral valve lesion with the other dizygotic twin. There is no evidence for the precise genetic or environmental (intrauterine/extrauterine) back- ground of congenital posterior mitral valve cleft. However, previous publications suggest that twins appear to be as- sociated with an increased risk of congenital heart diseases compared with singletons (Bahtiyar et al., 2007; Campbell et al., 2009). It appears that the interplay of altered pla- centation in conjunction with a genetic predisposition may play some part in this increased congenital heart disease risk (Bahtiyar et al., 2007; Bjarneg˚ard et al., 2013). There- fore, we assume that beyond genetic effects, the altered local intrauterine environmental factors (altered placental hemo- dynamics and vascular factors) might also play a role in the development of mitral valve cleft. In order to verify this, further investigations should be performed on larger twin populations.
to the same fetus, this was labeled as a non-anastomotic pair. On the other hand, if the terminal end of an artery was accompanied by a returning vein to the other twin, this was labeled as an A-V anastomosis. A-A anastomoses were apparent, since the artery of one twin would continue as an artery to the other twin. Similarly, V-V anastomoses could be identified by following a vein from one twin to the other. The identification of these anastomoses did not rely on the location of the dividing membrane on the surface of the placenta. This avoided missing anastomoses located in the sac of the donor, whether this meant a few or even all of the anastomoses. Visualization of the anastomoses through the dividing membrane within the sac of the donor was also shown to be possible. This was in contrast to previous reports, where presumably the anastomoses within the sac of the donor were not visible due to the presence of two layers of amnion (De Lia et al., 1993). In fact, the two layers of amnion do not preclude visualization of the anastomoses within the sac of the donor twin, particularly when there is severe oligohydramnios or anhydramnios in the sac of that fetus. The selective technique provided a reproducible way of identifying all of the vascular anastomoses, independent of their location, a first step in the proper performance of the laser surgical technique. R. Quintero, L. Quintero L., (2000) also reported how to document the vascular anastomoses. This included mentioning the size (hair, small, medium, large, extra-large) of the anastomoses, as well as their direc- tion (from donor to recipient or from recipient to donor). The direction of flow in A-A or V-V anastomoses cannot be determined in most cases, unless significant discoloration is present in these vessels from differences in fetal SpO2 (Quintero et al., 2008). In cases with significant discol- oration differences, the collision front between the two fetal circulations within an A-A or a V-V anastomosis led to the concept of the ‘hemodynamic equator’ (HE; Chang et al., 2006). The HE allowed, for the first time, a better under- standing of the actual behavior of A-A or V-V anastomoses, which until then were thought to be bidirectional in all cases. Indeed, if the HE moves back and forth between draining vessels of either twin, the behavior of the A-A or V-V anas- tomosis is truly bidirectional. On the other hand, if the HE only reaches a draining vessel of one twin, the function of the superficial vessel is essentially no different than an AV anastomosis (and, as such, labeled as fAVDR if from donor to recipient, or fAVRD if from recipient to donor). Lastly, if the HE does not reach any draining vessel, the net exchange of blood between the fetuses through that vessel is zero.
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planned vaginal delivery (VD) to planned cesarean sec- tion (CS) in twin pregnancies between 32 and 38 weeks gestation where the first twin was in a cephalic presenta- tion at the time of randomization . The study re- ported there was no difference in fetal and neonatal outcomes between the two approaches. In this nonran- domized secondary analysis of the TBS data on women who had induction of labor, the primary objective was to compare the rate of unplanned CS and safety between various induction methods that were employed both on neonatal and maternal mortality or serious morbidity.
The triplets were all born in good condition, with the birth weight of the donor and recipient female twins 1,055 g and 1,315 g respectively, and the singleton male 1,435 g. The diagnosis of recurrent TAPS was confirmed postnatally, with the Hb of the donor twin, 111 g/L (reticulocyte count 496), and the recipient twin, 232 g/L (reticulocyte count 251); reticulocyte count ratio 1.98. The hemoglobin con- centration of the unaffected singleton was normal (168 g/L). Histopathology of the placenta confirmed the chorionicity, the presence of small anastomoses between the monochori- onic twins, and pallor of the donor twin placental territory. The donor twin needed no ventilation support, although the recipient twin required continuous positive airway pressure for 13 days, and the singleton for 2 days. The infants were finally discharged home in healthy condition at 38 weeks 4 days corrected gestational age. Recent pediatric follow-up at 17 months corrected gestational age has confirmed normal physical and neurodevelopment in all three triplets.
Example Scenario To better explain our approach to solving the problem of policy enforcement in this domain, in this section we present an example scenario and as- sociated policy. Figure 1 illustrates the scenario in which the expert scientist in an organisation has a personalised registry (Registry 1) that copies the service adverts published in one or more public registries. The expert then adds a trust value as metadata to each service advert, indicating how reliable they have found that service. A novice in the same organisation also has a personalised registry (Registry 2) that copies the content of the expert’s registry, but only where the trust value of a service is higher than a particular defined constant. The novice is the only user allowed to edit the metadata in Registry 2. This means that when the novice discovers services, they are only provided with services that the expert has judged to be regarded as trustable.
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The twins were drawn from the Swedish Adoption Twin Study of Aging (SATSA) and the Gender Study. Twenty twins (from both intact and non-intact pairs) had been reared together while 15 twins had been reared apart. Among the reared-apart group, eight twins had been sepa- rated early in life and raised by unrelated families living far from one other; first contacts occurred several years later. In contrast, seven reared-apart twins had been raised by rela- tives and lived within close proximity to one another. Sam- ple questions were: ‘What was it like to be a twin when you were a teenager?’ and ‘What is it like now as you get older?’. The nature and quality of the twin relationships were organized into three categories: Nurturing (emotionally close; supportive; loyal), Draining (emotionally close, but dependent; conflicting communication; competitive), and Superficial (emotional distance; lack of familiarity; little in common). Twenty-four twins (10 MZ, 14 DZ) were in the Nurturing group, while eight twins (only MZ) were in
The Zika virus has affected hundreds of newborn infants in Brazil and other countries, and twins are among them. A recent article in the New York Times described the sit- uations of infants in nine twin pairs, underlying their im- portance for understanding why some pairs are concordant and other pairs are discordant (Belluck & Franco, 2017). According to Universidade de São Paulo geneticist Mayana Zatz who was interviewed for the article, both twins were affected in two identical pairs, whereas only one twin was affected in six fraternal pairs, with the exception of one con- cordant fraternal (male-female) pair. The writer of the ar- ticle stated that, ‘Since identical twins share one placenta while fraternal twins almost always have separate placen- tas, Dr Zatz and other experts suggested that the Zika virus may have penetrated one placenta and not the other’ (pp. D1, 6). Of course, this assertion is false as I indicated in an unpublished letter to the newspaper’s editorial divi- sion and in my recent book, Twin Mythconceptions (Segal, 2017).
(Colour online) Pooled survival (forest plot) of twin pregnancies complicated by Quintero stage 1 twin-to-twin transfusion syndrome (TTTS) managed by endoscopic laser photocoagulation. The overall survival (a), double survival (b), and at least 1 survival (c) are shown. Each study is represented by a line. The box in the middle of the line represents the point effect estimate of this particular study. The midpoint of the box represents the point effect estimate, that is, the mean effect estimate for each study. The area of the box represents the weight given to the study. The diamond below the studies represents the overall estimate. The width of the line shows the confidence interval (CI) of the effect estimate of individual studies. The width of the diamond shows the CI for the overall effect estimate.
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From the manuscripts, the reviewer (ARW) extracted the following information (if available): author, year, title, administrative data (e.g., clinical cohort or registry), country, patient selection criteria (e.g. age, KL grade), subgroup information, size of analysis group, mean age, analysis method (e.g., cumulative incidence), duration between arthroscopy and TKA, duration of follow-up, percentage of TKA, and study arm population description. Another reviewer abstracted key data (e.g., country, administrative data, patient selection criteria, follow-up years, analysis group, and total TKA numbers) from the included studies. The results from both abstractions were compared and found to be the same.