bluuebunny/crossref_metadata_2025_split huggingface dataset:
Birthweight Differences, The Transfusion Syndrome and The Cognitive Development of Monozygotic Twins
Authors: O'Brien P.J. , Hay D.A. 
Published: July 2016

AbstractMonochorionic twins may differ from dichorionic monozygotic (MZ) twins because of the transfusion syndrome and the timing of the cleavage of the zygote. Intrapair birthweight differences may be an indicator of these intrauterine variables. Previous evidence concerning weight differences and intellectual ability in MZ twins is reviewed with recommendations that future research also incorporates full placental data. Poorer scores on a nonverbal test are found for the lighter male twin of pairs with large intrapair differences in birthweight. Co-twin concordance rates for test scores are also highest for this group indicating that they vary consistently from other groups. Some evidence is presented from the present and earlier studies implicating anomalies of asymmetry or the transfusion syndrome as possible causes of these differences in brain functioning. The study adds further doubts as to the validity of any assumption of developmental equivalence between MZ twins and the general population.
Weight and Height Growth in Twins and Children Born in the Last Decade
Authors: Alfieri A. , Gatti I. , Alfieri A.C. 
Published: July 2016

AbstractWeight and height growth has been examined in 400 twins and 229 singletons born 1975-1985. Periodical measurements have been taken from 0 to 7 years of age. As compared to values obtained in a previous study of twins and singletons born 1960-1974, though limited to the first year of age, twins appear to continue to do worse than singletons in their growth. However, height values appear to have become higher in the first year of age in both twins and singletons born 1975-1985.
Autonomous Languages of Twins
Authors: Bakker Peter 
Published: July 2016

AbstractTwins are regularly reported to invent languages of their own, unintelligible to others. These languages are known as autonomous languages, cryptophasia or idioglossia. Despite current belief, this is not a rare phenomenon. Autonomous languages exist in about 40% of all twins, but often disappear soon. In this study, nine autonomous languages are compared: the circumstances in which they emerge, how these languages relate to the parents' language (the model language) and how they are structured. The prototypical situation is one in which two or more close siblings (not necessarily twins) grow up closely together during the language acquisition period. If an adult model language is frequently absent, the children use each other as a model and acquire the language imperfectly. The language may stabilise at that level. If a model is completely absent, the children probably do not create a language. In all cases known, the language consists of onomatopoeic expressions, some invented words, but for the greatest part of words from the adult language adopted to the constrained phonological possibilities of young children. These words being hardly recognizable, the language may turn out to be completely unintelligible to speakers of the model languages, but they resemble each other in that they lack morphology and that word order is based on pragmatic principles such as saliency and the semantic scope of words. Neither the structure of the languages nor its emergence can be explained by other than situational factors.
Innovations in the Statistical Analysis of Twin Studies
Authors: Hopper J.L. , Derrick P.L. , Clifford C.A. 
Published: July 2016

AbstractAdvances in computer technology have made possible a greater sophistication in the statistical analysis of pedigree data, however this is not necessarily manifest by fitting more comprehensive causative models. Planned twin and family studies measure numerous explanatory variables, including perhaps genetic and DNA marker information status on all pedigree members, and the cohabitation of all pairs of individuals. A statistical analysis should examine the contribution of these measured factors on individual means, and in explaining the variation and covariation between individuals, concurrently with the postulated effect of unmeasured factors such as polygenes. We present two models that meet this requirement: the Multivariate Normal Model for Pedigree Analysis for quantitative traits, and a Log-Linear Model for Binary Pedigree Data. For both models, important issues are examination of fit, detection of outlier pedigrees and outlier individuals, and critical examination of the model assumptions. Procedures for fulfilling these needs and examples of modelling are discussed.
Design and Sampling Considerations, Response Rates, and Representativeness in a Finnish Twin Family Study
Authors: Kaprio J. , Rose R.J. , Sarna S. , Langinvainio H. , Koskenvuo M. , Rita H. , Heikkilä K. 
Published: July 2016

AbstractKinships composed of twin parents, their spouses and children, offer a robust and flexible sampling design for research in genetic epidemiology. Families-of-twins designs circumvent some of the sampling problems that arise when independent data sets are combined, and these designs provide unique evaluations of maternal influences, assortative mating and X-linkage. Unfortunately, empirical studies of families of twin parents have been limited by relatively small samples and by the self-selection biases intrinsic in ascertainment of families from volunteer twin registries.A large and representative cohort of monozygotic and dizygotic twin parents, drawn from a population-based twin registry, provides the optimal sampling frame for twin-family research. This paper reviews the sampling considerations underlying the initial family study based on the Finnish Twin Cohort and evaluates the representativeness of the sampled twins. Spouses and adult children (over 18 years) of 236 pairs of twins, about equally divided by gender and zygosity, were evaluated by a postal questionnaire. Individual response rates exceeded 86% and in 464 of the 472 nuclear families (98.3% ), at last one member of the twin's family completed the questionnaire. The sampled twins, selected for fecundity to maximize statistical power of the obtained data, were broadly representative of non-selected twins drawn from the Cohort, with whom they were matched on age, gender, and zygosity. Such results suggest that the Finnish Cohort has excellent potential for extended twin-family research designs.
Differential Enrollment in Twin Registries: Its Effect on Prevalence and Concordance Rates and Estimates of Genetic Parameters
Authors: Kendler K.S. , Holm N.V. 
Published: July 2016

AbstractIn the NAS-NRC Registry, all major diseases are more common in DZ than in MZ twins. Furthermore, concordance rates for most disorders are lower in the registry than would be expected. In this article we propose a general model which seeks to explain these phenomena. The model explores the impact of traits which increase or decrease the probability of enrollment of individuals given that the registry, like the NAS-NRC, includes only pairs where both members are enrolled. If the trait decreases the probability of selection into the registry, both the prevalence of and concordance for the trait in the registry will be lower than that found in the population. A trait which increases the probability of selection has the opposite effects. However, the magnitude of these effects are a function of the population concordance. If population concordance differs in MZ and DZ twins, the effect of differential enrollment will not be the same for the two zygosity groups. The article examines the impact of differential enrollment on estimates of heritability and common environment and explores ways in which estimates of prevalence and concordance rates can be obtained which are free of the bias introduced by selection.
A Study of Multiple Biological Markers in Twins
Authors: Anton-Guirgis H. , Culver B.D. , Kurosaki T. , Elston R. 
Published: July 2016

AbstractGenetic and environmental influences on the phenotypic expressions of several biological markers were studied in 18 monozygous (MZ) and 8 dizygous (DZ)twin pairs. Zygosity was determined using ABO, Rh, and HLA. The biomarkers studied included: T & B lymphocytes, suppressor and helper T lymphocytes (Tγ, Tμ), T cell (PHA) mitogen activation (MA), serum immunoglobulins (IgA, IgM, and IgG), plasma carcinoembryonic antigen (CEA), aryl-hydrocarbon hydroxylase (AHH) and sister chromatid exchange (SCE) in lymphocytes. Temporal variation of markers over a 6-month period was not significant. The mean absolute differences between levels from first and second blood draws were less than one standard deviation. Variability associated with age was not significant. Females had higher levels of T lymphocytes than males. A gender related association was observed for the IgM immunoglobulin test: females had a higher mean level of IgM. Smoking was found to influence the levels of SCE, T helper lymphocytes and mitogen activation. The variability of these biomarkers within and between twin pairs was quantified. Immunoglobulin levels, particularly that of IgM, showed statistically greater similarity within MZ twins than within DZ twins. Several other markers suggested heritability.
Acute Polyhydramnios Complicating Twin Pregnancies
Authors: Schneider K.T.M. , Vetter K. , Huch R. , Huch A. 
Published: July 2016

AbstractAcute polyhydramnios in the second trimestr is a typical complication in monozygous twin pregnancies. It is caused by a feto-fetal transfusion with anemia on the donor and polycytemia on the recipient twin. Contrary to the chronic hydramnios, there is no increase in malformations. In view of the high mortality rate (100%, according to most authors), the clinical management has to be reconsidered. During the years 1979 to 1983, 10 cases of acute polyhydramnios have been observed at the University Hospital in Zurich. This corresponds to an incidence of 9% in our twin population. All cases investigated were MZ twin pregnancies. With the exception of one patient, who underwent an abortion, all women were hospitalized, had bed rest and received recurrent removals of amniotic fluid and prophylactic tocolysis. The mean gestational age at the time of diagnosis was 23 4/7 weeks and at delivery 30 3/7 weeks. In two cases – one of which is presented in detail – with an unintentional puncture of a placental vessel, the recurrence of the hydramnios did not appear. Eight of 18 newborns survived. No malformations were found. Bed rest, tocolysis and recurrent amniocenteses seem to have a positive influence on the prolongation and outcome of the gestation in acute polyhydramnios.
Is Routine Hospitalization in Twin Pregnancy Necessary? A Follow-up Study
Authors: Hartikainen-Sorri Anna-Liisa 
Published: July 2016

AbstractDuring the years 1979-1980, a prospective study was carried out to evaluate the value and efficacy of routine hospital bed rest in the prevention of premature birth and pregnancy complications in twin gestation. This was done by comparing hospital bed rest to special antenatal care at outpatient clinic. Since the results did not support the idea of using routine hospital bed rest, this was abandoned. Because the material was rather small, the results of the changed policy of management were controlled in the present follow-up study. The material consists of 102 twin pregnancies diagnosed during the years 1982-1983. The number of deliveries before the 34th gestational week and of < 1500 g weighing infants were still decreasing (9.0% and 3.0%). Perinatal mortality after the 24th gestational week was 2.0%. The follow-up study confirmed the unefficacy of routine hospital bed rest. Early diagnosis is the basis of the management of twin pregnancy. This allows counselling of the pregnant women, regular examinations to detect pregnancy complications, and also planning of the delivery.
Triplets and Higher Order Multiple Births in Japan
Authors: Imaizumi Y. 
Published: July 2016

AbstractMultiple birth rates in entire Japan were analyzed using vital statistics for 1951 to 1988. The triplet rate was nearly constant from 1951 to 1974, where the rate per million births was 58, then increased with the year up to 1982 (104), and decreased up to 1984, and suddenly increased thereafter (109 in 1987). The average rate of quadruplets per million births from 1951 to 1968 was 0.93, then increased with the year up to 1975 (7.5), and decreased until 1984 and suddenly increased thereafter (10.6 in 1987). The rate of quintuplets was 0.77 per million births during the period from 1975 to 1987. The higher multiple birth rate since 1975 was attributed to the higher proportion of mothers treated with ovulation-inducing hormones in Japan. Since 1985, higher multiple birth rates might be partially attributed to in vitro fertilization. The stillbirth rates for male triplets gradually decreased from 1960 to 1978 and thereafter remained constant at a little higher level except in 1988, whereas the rates for females gradually decreased with the year. The overall stillbirth rates decreased to 1/4 for triplets and to 1/5 for quadruplets during the 37-year period from 1951. The overall stillbirth rate of quintuplets was 0.60 (51/85) during the period 1975-1987.
Multiple Pregnancy: An International Perspective
Authors: Sciarra J.J. , Keith L.G. 
Published: July 2016

AbstractThis article discusses the following areas of interest related to the obstetric care of multiple pregnancy: 1) methods of diagnosis and ultrasound, 2) pregnancy protection through adequate maternal nutrition, 3) mode of delivery, 4) discordant twins, and 5) assisted reproductive technology. The article also emphasizes the FIGO/WHO concerns regarding safe motherood and proposes a four point program to reduce perinatal death rates in multiple pregnancy. These elements are: 1) adequate primary health care including access to family planning information and technology, 2) prenatal care with referral of high risk patients to specialized centers, 3) the presence of trained personnel for all women in childbirth, 4) effective access to obstetric care for women who are pregnant, giving birth, or recently delivered.
The Cost Effectiveness of Preventing Preterm Delivery in Twin Pregnancies
Authors: Papiernik E. , Keith L.G. 
Published: July 2016

AbstractAs an extension of previous work on the risk of prematurity in singletons and on the social cost of twin births, an analysis has been carried out into the cost effectiveness of preventing premature delivery in twin pregnancies. The cost of prevention is assessed in terms of early diagnosis through ultrasound screening and of an extra 11 weeks of work leave to expectant mothers. When this cost is compared to the social cost involved in the transfer of newborns to neonatal intensity care units and in supporting handicapped children, it is concluded that the total cost of prevention corresponds to one-third of the long-term costs associated to lack of prevention.
Guidelines for the Prevention of Multiple Pregnancy in Treatment by in Vitro Fertilization
Authors: Leroy F. , Puissant F. , Barlow P. , de Maertelaer G. 
Published: July 2016

AbstractWithin the same in vitro fertilization (IVF) program, treatment trials leading to single and multiple ongoing gestation were compared. Rates of cesarean delivery, prematurity and perinatal mortality were found much higher among twin and multiple IVF pregnancies. Our work thus attempts at defining characteristics of proneness to multiple gestation in IVF treatment, in order to try and avoid its occurrence. The mean vitality score of embryos replaced is the most reliable criterion for this purpose, enabling one to replace no more than two embryos when the average score is high. Age of the patient and cause of infertility are almost nondiscriminant in this respect. Ovarian stimulation parameters such as total dosage of gonadotropin treatment and level of estrogenic response, as well as numbers of oocytes and embryos obtained, may serve as secondary criteria for assessing the twinning risk.
A Study on Prognosis of Surviving Cotwin
Authors: Yoshida K. , Matayoshi K. 
Published: July 2016

AbstractIt has been suggested that the surviving cotwin and the mother are seriously affected when intrautrine fetal death of one monozygotic twin occurs. Several authors have reported brain damage in the surviving twin coexisting in utero with dead monozygotic cotwin. Most of such instances are monochorionic and show vascular communication between paired twins in the placenta. In a total of 133 pairs of monochorionic twins, death of one twin during pregnancy occurred in 33 cases (24.8%). Of 33 surviving twins, 8 babies suffered from porencephaly, cerebral palsy and other abnormalities. More unfavorable prognosis was recognized when a cotwin died in the latter half of pregnancy, while when a monozygotic cotwin died in the early stage of pregnancy, the surviving twin uneventfully grew to term in most cases.
Genetic Influences on Respiratory Sinus Arrhythmia across Different Task Conditions
Authors: Boomsma D.I. , van Baal G.C.M. , Orlebeke J.F. 
Published: July 2016

AbstractRespiratory sinus arrhythmia (RSA) has been shown to be a sensitive index of vagal cardiac control. We studied the genetic and nongenetic influences on individual differences in RSA in a sample of 160 adolescent twins. RSA was measured during rest and across two different tasks. Results show that heritability is task dependent. The amount of genetic variance is the same, however, during rest and task conditions. Because nonshared environmental variance decreases during tasks, heritability is larger for RSA measured under more stressful conditions than for RSA as measured during rest. Multivariate models assessed the continuity of the genetic and environmental influences and show genetic influences to be the same across different conditions, while environmental influences are different. More specifically, a one-factor model is found for genetic influences and a second-order autoregressive model for the environmental factors.
“Twins in School” — An Australia-wide Program
Authors: Gleeson C. , Hay D.A. , Johnston C.J. , Theobald T.M. 
Published: July 2016

AbstractThe multiple birth family is more likely to have a dispute with the education system than with any other service. So many potential areas of conflict exist over the abilities and behaviour of multiples and over such issues as separation or keeping back one twin. One reason for disputes is the lack of good data to adequately reflect the different perspectives of parents and teachers and the differing needs of families: the same solution does not apply to all. To provide the first large-scale data base and building upon an initial survey of 85% of all primary school teachers in South Australia, the LaTrobe Twin Study and AMBA worked with Education Departments to set-up in each state Education Research Teams (ERTs) of parents of multiples who were also teachers. The ERTs were crucial in three phases. 1) Developing and circulating questionnaires and publicising the nationwide survey. 784 families and 1264 teachers of their children completed these questionnaires, many reporting that simply having to address the issues raised in the questionnaire was a valuable learning experience. 2) Exploring the data base. Issues arising included the very different bases on which parents and teachers judged separation desirable, with teachers emphasising the unsubstantiated claim that separation is essential to individual development. Separation became more common over the first three years of schooling but 20-25% of twins separated one year were back together the next. 3) Running regional meetings of parents, teachers and administrators to discuss the results and to pool experiences and plan policies at the local level. A need clearly exists to improve the level of consultation between families and school personnel and to ensure the widespread availability of information which identifies key issues in making decisions for that multiple birth family.
Heritability of Substance Use in the NAS-NRC Twin Registry
Authors: Carmelli D. , Swan G.E. , Robinette D. , Fabsitz R.R. 
Published: July 2016

AbstractThis study examines the heritability of cigarette smoking, alcohol, and coffee consumption in 4,960 adult, male twin pairs (2,390 MZ and 2,570 DZ pairs) participants in an epidemiologic survey of the NAS-NRC Twin Registry conducted in the USA during 1972-73. Heritability estimates for smoking, alcohol and coffee use were calculated both before and after adjustment for shared variance between these behaviors and other demographic characteristics including socioeconomic status and an occupational adjustment score. The objective of the analysis was to determine the impact of adjustment for covariates on heritability estimates of smoking, alcohol and coffee use. Before adjustment, genetic effects in smoking, alcohol and coffee use accounted for 53%, 36%, and 45% of the variance, respectively. After adjustment, the corresponding estimates were 35%, 29%, and 36%. The fact that these estimates remained significant after adjustment for covariates leads to increased confidence about the role of genetic factors in substance use behaviors.
Zygosity Diagnosis of Twins by Questionnaire
Authors: Ooki S. , Yamada K. , Asaka A. , Hayakawa K. 
Published: July 2016

AbstractSubjects were 189 twin pairs, 165 MZ and 24 same-sexed DZ, who entered the junior high school affiliated to Tokyo University (sample T), and 93 twin pairs, 71 MZ and 22 same-sexed DZ, who were registered at Kinki University (sample K). The zygosity was previously identified by many genetic markers, and this study aimed at zygosity diagnosis by questionnaire. The latter included three questions: “How are you alike?”, “How often are you mistaken?”, and “By whom are you mistaken?”. According to the degree, 1-3 points, 1-3 points, and 1-4 points were given for each question, and the sum of the points of each pair of twins was calculated. Zygosity was determined by the sum of points, distributed from 6 to 20. Namely, if the sum was 6-13, the twin pair was considered MZ, and if the sum was 14-20, DZ. More than 90% of twins were diagnosed correctly by use of this cutting point. This result was in accordance with that obtained by use of discriminant function analysis. It is concluded that zygosity diagnosis by questionnaire is convenient and useful, in particular for epidemiological research.
Incidence of Twinning in London from 1581 to 1760
Authors: Nonaka K. , Miura T. 
Published: July 2016

AbstractBaptism records of parishes in London and its vicinities from 1581 to 1760 (168,238 maternities) were investigated to estimate the twinning rate and its secular and seasonal variations. Total, estimated dizygotic (DZ), and estimated monozygotic (MZ) twinning rates were 1.1%, 0.8% and 0.3%, respectively. MZ twinning rate varied during the 18 decades, with a significantly low rate (0.11%) in the early 17th century (1621-1640). Significant seasonal variations of the twinning rate according to the month of baptism was observed in both DZ and MZ twins. DZ twins were born more frequently in spring and fall in general. Parish records obtained from four parishes near Manchester in England showed an inversed seasonal variation with peaks in winter and summer. An interpretation of this difference was discussed in a context of environmental factors. In the low MZ period, 1621-1640, MZ or like-sexed twins were apparently less frequent in summer (Aprii to October). This result could be explained by a decrease of MZ twins and/or a greater loss of like-sexed DZ twins.