bluuebunny/crossref_metadata_2025 huggingface dataset:
Zygosity Partitioning of Small Twin Samples
Authors: Allen Gordon , Hrubec Zdenek
Published: July 2016

When the Weinberg estimate of the proportion of monozygotic pairs is quite deviant from that in the source population, it is likely to be wrong because Weinberg's difference is much less stable than the zygosity proportions. A formula is proposed for the probability distribution of possible compositions of a small sample of twins based on sex concordance in the sample and zygosity proportions in the source population.
An Assessment of Perinatal Mortality in Twin Pregnancies in Dundee
Authors: Osbourne G.K. , Patel N.B.
Published: July 2016

An analysis of all perinatal deaths occurring in twin pregnancies in Dundee women from 1956 to 1983 was performed. The uncorrected perinatal mortality rate fell from 116/1000 births in 1956-60 to 16/1000 births in 1981-83, this fall almost entirely taking place after 1975. Causes of death were identified using the Aberdeen Classification and a reduction in deaths in all cause groupings occurred. About half of the deaths were in the Premature, Cause Unknown group and a marked decrease in deaths in this group made the largest contribution to the improved perinatal mortality rate. This fall was partly due to a reduction in the incidence of extreme prematurity and low birth weight. Changes in obstetric management which may have influenced outcome included the introduction of routine early pregnancy ultrasound scanning, the use of tocolytic drugs, intrapartum fetal monitoring, epidural analgesia and an increase in Caesarean section rate from 2% in 1956-60 to 39% in 1981-83.
A Low Rate of Perinatal Deaths for Twin Births
Authors: Papiernik E. , Mussy M.A. , Vial M. , Richard A.
Published: July 2016

A specific prenatal care program is proposed to prevent preterm deliveries in twin pregnancies, with ultrasound scanning, early work leave and home visits by midwifes. A four-year study has been conducted on 197 pregnancies (160 early followed and booked and 37 late referred). It can be shown that early preterm births and very low birth weights are less frequent in the followed group than in published data, as well as in the late referred pregnancies. The total perinatal mortality rate is 25.6 per 1000 total births.
Management in Second Stage of Labour in Term Twin Delivery
Authors: Olofsson P. , Rydhström H.
Published: July 2016

A simple program for management of term twin delivery in the second stage of labor is presented. Provided that given selection criteria are met, twins at term are delivered by the vaginal route
Cardiac Output in Twin Pregnancy
Authors: Campbell D.M. , Haites N. , MacLennan F. , Rawles J.
Published: July 2016

No significant difference has been found in either stroke volume or cardiac output between twin pregnancies and singleton pregnancies. Cardiac output is less in preeclamptic twin pregnancies.
Bed Rest in Twin Pregnancy
Authors: Kappel B. , Hansen K.B. , Moller J. , Faaborg-Andersen J.
Published: July 2016

A total of 146 twin pregnancies were studied to evaluate the importance of bed rest. A significantly reduced frequency of preterm delivery was found after bed rest in hospital as compared to bed rest at home or no bed rest at all. An increase in gestational age and in birth weight was seen after bed rest. No effect was found on the intrauterine increase of fetal weight per time. Early routine ultrasound is recommended, so that effective bed rest may be instituted in due time.
President's Address: Twinning in Families of Triplets
Authors: Eriksson A.W.
Published: July 2016

A study was conducted on twinning in relatives of consecutive triplet sets in the Åland Islands in the years 1740-1939. The incidence of twinning in sibships of triplets was extremely high, 80/1000 (56/1000 before and 143/1000 after the triplet maternity). In Finland as a whole, 1905-1954, the twinning rate was among mothers of triplets 38/1000, ie, about 2.6 times the rate in general population, and was higher after (48/1000) than before the triplet maternity (34/1000). In the sibships of fathers of triplets there was a low rate of twinning (below 10/1000) both of same-sexed (SS) and of opposite-sexed (OS) triplets. Among sibships of mothers of OS triplets the twinning rate was 18/1000 and among mothers' sibships of SS triplets 26/1000. The series of triplet families from both Åland and Finland as a whole indicate a considerably higher frequency of twinning on the maternal than on the paternal side. The sibships of OS triplets in Finland have higher twinning rates than sibships of SS triplets (50/1000 vs 27/1000). In sibships of triplets, not only the DZ but also the MZ twinning rates were approximately twice as high as those in the general population. The triplet rates in Finland were increasing strongly with maternal age and were in the last century among mothers of 30-39 years of age considerably higher than among mothers from this century. This, in combination with higher mean parity, may explain the high rates of multiple maternities in sibships of triplets in the past. The rate of triplet maternities seems to be more sensitive to sociodemographic changes than the rate of twin maternities. Mothers of triplets in Finland had a high frequency (more than 40%) of prenuptially conceived firstborn children. This, and a short protogenesic interval indicate that triplet-prone mothers are more fecundable, ie, they conceive with greater ease and/or may have a better physical condition than other women for completing a gestation with multiple embryos.
Trends in Monozygotic and Dizygotic Twinning Rates by Maternal Age and Parity — Further Analysis of Italian Data, 1949-1985, and Rediscussion of US Data, 1964-1985
Authors: Allen G. , Parisi P.
Published: July 2016

The dizygotic twinning rate in Italy, adjusted for maternal age and parity, declined from 8.9/1000 in 1949-1953 to 6.0/1000 in 1978-81, but may have stabilized or recovered slightly in the early 1980s. The long decline was greatest in the oldest mothers, and the recent increase, if any, has been principally in first births and in women under 30. The monozygotic rate rose from 3.8/1000 in 1969-73 to 4.3/1000 in 1982-85, having been relatively stable prior to that period. No good explanation for these trends is apparent.
Decrease in Twinning Rate in a Hospital in Tokyo During World War II
Authors: Nakamura I. , Nonaka K. , Miura T.
Published: July 2016

In order to investigate changes in twinning rate during World War II and postwar years, when the people in Tokyo suffered from malnutrition, about 80,000 delivery records during 1924-86 at one hospital in downtown Tokyo were examined. The twinning rate decreased from 1.47% in the 1920s to 0.81% in the 1980s. During the 1940s, the rate was 1.03% for 1940-42 and 0.94% for 1948-49, but it dropped down to 0.70% for 1943-47. In 1945, when Tokyo was heavily bombed repeatedly to be burnt out, and the people suffered from severe malnutrition, only one case of twinning was found among 305 maternities at this hospital (0.33%). While the mean birth weight of term singleton babies was 2953 g in 1940-41, it decreased to 2918 g in 1943-47, especially to 2856 g in 1945. This change in birth weight evidenced that the nutritional conditions in Tokyo became worse in 1943-47. This report suggests that the twinning rate decreased also during this period in Tokyo when the people suffered from malnutrition.
Living Habits and Personality Development of Adolescent Twins: A Longitudinal Follow-up Study in a Birth Cohort from Pregnancy to Adolescence
Authors: Moilanen I. , Rantakallio P.
Published: July 2016

The living habits of 289 twins in a one-year birth cohort beginning during pregnancy and followed up to adolescence were compared with those of 11,623 singletons and two sets of controls matched either by maternal factors and place of residence only or by these and perinatal morbidity, all from the same cohort. The twins went in for sports more often than the singletons or any kind of controls. A nonsignificant trend was found indicating that twins smoked less often than their matched controls. The twins also used alcohol less often than their controls. The intrapair similarities of twins were higher than the similarities of twins and either type of controls in all four variables tested: sports, smoking, use of alcohol, as well as having been drunk.
Qualitative and Quantitative Aspects on Mathematics Achievement in MZ and DZ Twins
Authors: Lange A.L. , Fischbein S.
Published: July 2016

Mathematics achievement test results have been collected for 22 MZ and 24 DZ same-sex twin pairs in the Swedish compulsory school. The twins were approximately 11-13 years of age and attended grades 4, 5, or 6. The twin pairs were part of a larger collaborative study between Israel and Sweden (the KAM-project). Teachers were asked how they planned and evaluated their work in the subjects Swedish and Mathematics. In addition to this, results for the twins on Maths tests given by the teachers in their regular work were collected. These tests were thus used by the teachers as an instrument to evaluate the educational process. Intrapair similarity for MZ and DZ twins has been compared for qualitative and quantitative aspects of the Maths tests. Different tests were used by the teachers but the same criteria have been used in the comparison. MZ twins are somewhat more similar than DZ twins for both the qualitative and quantitative aspects. Only one quantitative aspect, however, percentage of correct answers, shows a significant difference between the twin categories. A comparison was also made of intrapair similarity in classes, where the teachers differed according to planning and evaluation of their education. Irrespective of that, the MZ twins seemed to be more similar than the DZ twins in number of correct answers on the Maths tests. Educational implications are discussed.
Using MZ Twins in Experimental Research to Test for the Presence of a Genotype-Environment Interaction Effect
Authors: Bouchard C. , Pérusse L. , Leblanc C.
Published: July 2016

Despite some evidence that genotype-environment interaction (G×E) effects may be involved in the variation observed in behavioral and biological traits, few attempts have been made to detect and quantify this component of genetic variation in humans. We propose that one way to achieve this goal is to challenge several genotypes in a similar manner, submitting both members of several MZ twin pairs to an ethically acceptable experimental treatment capable of inducing an adaptative response. In this situation, the G×E effect can be assessed with a two-way analysis of variance for repeated measures on one factor, the treatment effect. In this design, twins are considered nested within the pair, whereas the treatment effect is considered a fixed variable. The intrapair resemblance in the response to the treatment is quantified with an intraclass correlation coefficient computed with between-sibhips and within-sibhips means of squares. To illustrate this approach, changes induced by long-term endurance training were studied in 10 MZ twin pairs. Significant intrapair resemblance in the response of maximal oxygen uptake was observed, with about 7 to 8 times more variance between pairs than within pairs. This design with MZ twins may be helpful in the study of human variation for multifactorial phenotypes.
Chronogenetics: A Meeting Point for Medicine and Twin Research
Authors: Gedda Luigi
Published: July 2016

The program of any individual's vital cycle encoded in the genetic information is executed according to a time schedule that is the object of study of Chronogenetics. MZ twins provide the best evidence of the existence of this hereditary biological time and they represent, therefore, the natural test of Chronogenetics. Twin research can thus serve medicine in developing its most modern perspective, individual preventive medicine. Moreover, through approaches such as the Twins-Living-Apart Test, twin research can help to identify the influences of the environment on the health of man.
Familial Factors in Mortality with Control of Epidemiological Covariables. Swedish Twins Born 1886-1925
Authors: Hrubec Z. , Floderus-Myrhed B. , de Faire U. , Sarna S.
Published: July 2016

A Cox proportional hazard regression analysis was carried out that evaluated age-specific death risk among 21,890 twins born in Sweden during 1886 through 1925 and followed during 1962 through 1980. Cotwin's survival was used as the primary covariable, and auxiliary covariables were smoking, marital status and, among men, police registration for alcohol abuse. In each age, sex and zygosity group, except the oldest DZ males, cotwin's mortality had a significant, independent, positive relationship to the mortality risk of the individual. The auxiliary covariables, except marital status among females, had significant, independent, positive relationships to mortality among the youngest twins of both zygosity groups and in the middle age group of MZ twins. In the oldest age group, the death of MZ cot wins was the only variable significantly related to the individual's mortality. Heritability estimates for the age-specific probability or death risk, developed by different methods for different analysis groups, range between 0.4 and 0.6. They have reasonable internal consistency, are not much affected by the covariates, and are in agreement with other studies that did not control covariates.
Responses of Blood Glucose and Serum Insulin to Peroral Glucose Load in Normoglycemic Twins
Authors: Kesäniemi Y.A. , Koskenvuo M. , Miettinen T.A.
Published: July 2016

Fasting blood glucose and serum immunoreactive insulin (IRI) and the responses of blood glucose and serum IRI to peroral glucose challenge were investigated in middle-aged normoglycemic male twins of 17 monozygotic (MZ) and 18 dizygotic (DZ) pairs recruited from the Finnish Twin Cohort Study. Also, the role of obesity and diet in the regulation of glucose and insulin metabolism was estimated. The fasting and 2 hr postprandial (PP) glucose showed higher pairwise correlations in MZ (r =0.78 and 0.56) than DZ (r = 0.08 and −0.05) pairs whereas fasting and PP insulin levels and the areas under the PP glucose and insulin curves were weakly and similarly correlated in MZ and DZ twins. The pairwise correlations of the 1/2 hr and 1 hr, but not the fasting and 2 hr insulin/glucose ratios, were somewhat higher in MZ (R = 0.51 and 0.53) than DZ (r = = 0.28 and 0.30) pairs. In MZ twins, the intrapair differences in the body mass index were significantly correlated with those in the fasting and 2 hr PP glucose and insulin levels and those in the fasting and 1/2 hr insulin/glucose ratios (r from 0.47 to 0.76). Also, the intrapair differences in the dietary fat calories were correlated positively, but those in the calories derived from carbohydrates negatively, with the intrapair differences in several parameters of the glucose and insulin metabolism. These data suggest that the environmental contribution to the regulation of glucose and insulin metabolism in subjects within the normoglycemic range may be quite strong. Of the environmental factors studied, obesity and dietary fat consumption seem to have powerful regulatory roles, particularly in the response of insulin to the glucose load.
Statistical Models for the Twinning Rate
Authors: Fellman J.O. , Eriksson A.W.
Published: July 2016

Linear regression models are used to explain the variations in the twinning rates. Data sets from different countries are analysed and maternal age, parity and marital status are the main regressors. The model building technique is also used in order to study the secular decline in the twinning rate. Linear regression technique makes it possible to compare the effect of different factors but the method requires sufficiently disaggregated data.
The Non-Decline in U.S. Twin Birth Rates, 1964–1983
Authors: Allen Gordon
Published: July 2016

Detailed twin birth rates for the United States are unavailable since 1964. In 1983 the crude twinning rate for women of white race was higher than in 1964, but there had been great changes in maternal age and parity. Indirect standardization for maternal age and birth order provides estimated total twinning rates that can be compared over the entire period. The adjusted rates for whites show a nearly continuous increase except after a 2-year reporting hiatus, 1969-70, when rates dropped back 10%. In blacks the adjusted rate increased between 1966 and 1978, except for the 1968-71 shift. The distributions of rate increases by maternal age and by race argue against effects of medical ovulation stimulants, but a disproportionate increase of triplets argues for such effects. Study is needed of rates specific for maternal age and parity, rather than of total rates.
Possible Mechanism of the Heredity of Twinning
Authors: Gedda L. , Brenci G.
Published: July 2016

It is a frequent observation that twinning runs in the families [5] and we have recently reported that such is also the case with Gregor Mendel's pedigree [4]. The problem we are concerned with, now, is the identification of the “gemellogenetic” factor postulated by Gedda already in 1951 [2].

We thought we should start by going back to experimental embryology. Clearly, as shown by the experimentally induced MZ twinning in Triton or the spontaneous multiple MZ twinning in Armadillo, there must exist a temporal threshold below which individual parts of a single conceptus can still show totipotence.

Interestingly, recent studies of molecular histology have stressed the role of cell membranes and of membrane receptors in the transmission of specific messages related to the position and function of the cell. This has led Edelman [1], in particular, to identify a specific kind of molecule that appears early in-embryonic development and is responsible for cell adhesion, thus contributing to organogenesis and the shaping of the embryo by regulating cell movements and the topologic development of tissues.

These so-called cell-adhesion molecules (CAM) are proteins that can differentiate both in function and in expression. In terms of function, there are molecules responsible for the adhesion of nerve cells (N-CAM), of liver cells (L-CAM), etc. In terms of expression, there are embryonic forms (E-CAM) and adult forms (A-CAM), the former being characterized by larger quantities of sialic acid. This chemical difference accounts for a different aggregation effect on the cells, that is, for a different cell adhesion. Moreover, the E-CAM and A-CAM can be interconverted, at different times and with variable speed.
Cost of Care and Prevention of Preterm Births in Twin Pregnancies
Authors: Tresmontant Raphaël , Héluin Gérard , Papiernik Emile
Published: July 2016

This study describes a 5-year survey of activity in a single institution, and the effects of a change of policy for prevention of preterm birth in twin pregnancies.

The results show the advantages and drawbacks from the financial and medical viewpoints.
Multivariate Logit Analysis of Concordance Ratios for Qualitative Traits in Twin Studies
Authors: Kaprio Jaakko , Sarna Seppo , Koskenvuo Markku
Published: July 2016

The application of multiway contingency table analysis to the multivariate analysis of concordance ratios in twin studies is developed. The approach is illustrated by data on smoking and alcohol use in Finland and Sweden. This approach can enable the assessment of the effect of other variables on the concordance ratio and thus allow estimates of genetic effects on the trait under study. Hypotheses on relationships between genetic effects and other variables can be tested. After hypothesis testing, model fitting of the best hypothesis can be carried out.
Back Pain: A Study of Twins
Authors: Bengtsson B. , Thorson J.
Published: July 2016

To evaluate the relationship between genetic factors and back pain, 5029 MZ and 7876 DZ twin pairs were investigated by a questionnaire. The data were analyzed with regard to physical symptoms, eg, back pain, and certain work conditions. Pain was reported by about 17% of the male and 13% of the female twins in the material. The occurrence of back pain was strongly associated with work load, especially among the male twins. Twin concordance regarding back pain was considerably higher in MZ than in DZ twins. Of four groups who were studied, statistically significant differences between the two twin categories were observed in three cases. This result supports the assumption that a relationship exists between genetic factors and the occurrence of back pain. Official registrations for sick-leave pay in a sample of 247 twins confirmed the interview information on back pain. Just a few cases were wrongly classified, ie, they were sick-listed because of back pain but had stated no back pain in the questionnaire.
Ophthalmic Disease in Twins: A Nationwide Record Linkage Study of Hospital Discharges and Free Medications for 16,067 Twin Pairs
Authors: Teikari J.M. , Kaprio J. , Koskenvuo M. , Vannas A.
Published: July 2016

Record linkage of the Finnish Twin Cohort Study with the Hospital Discharge Registry and with the Registry of Rights to Free Medication kept by the Social Insurance Institution gave following numbers of twin pairs with an ophthalmic disease (one or both members of the pair had the disease) in each disease category:98 with glaucoma simplex (5 concordant pairs), 38 with capsular glaucoma (no concordant pairs), 58 with iritis (no concordant pairs) and 149 with strabismus (2 concordant pairs).

The number of concordant pairs in each disease category was small, except for glaucoma simplex in which concordant pairs could be broken down by zygosity. The ratio of observed to expected (based on association by chance) was 6.96 for MZ and 1.74 for DZ pairs. This result suggests that genetic factors play some role in the variability of prevalence of simple glaucoma. Main etiologic factors are stili to be found in the environment. Data on occurrence of other diseases of ophtalmologic importance is presented.
Incidence of Double Occipital Hair Whorls in Twins and Singletons
Authors: Sharma Krishan
Published: July 2016

A sample of 122 twin pairs and 166 singletons from the urban Punjabi population of Chandigarh was studied. The observed frequency of double occipital hair whorls was higher in twins than in singletons (P < 0.01). The possible association between twinning and double occipital hair whorls is discussed.
High-Resolution Electrocardiography in Twins Affected by Situs Viscerum Specularis: Short Case Report
Authors: Campbell S. Villatico , Di Maio F. , Silvotti M.E. , Sciacca A. , Brenci G. , Gedda L.
Published: July 2016

We previously studied a pair of MZ twins with situs viscerum inversus of the heart, liver and stomach, concordant with regard to all other factors normally utilized to diagnose zygosity [3]. We have now reexamined them after three years to evaluate the development of their cardiovascular system.

Our male MZ twins, now 17 years old, have been examined with high-resolution electrocardiography (HRE), treadmill stress test with Bruce protocol, tests stressing the cardiovascular system (cold pressure test, handgript test, arithmetic mental test), and single and two-dimensional dynamic echocardiography after holter monitoring.

Atriogram analysis is made possible by HRE, that shows individual morphological reproducibility. Such reproducibility is present in both twins. In the dextrocardiac twin it is also present with the electrode position inverted. The similarity of morphology in the cotwins is further confirmed, even if such similarity is only apparent, in view of the fact that the vectors are spatially of opposite orientation, thereby causing an inversion of the electrical field [1-4]. The H-V interval is normal, although in the dextrocardiac twin it is longer (30 ms) than in his cotwin (25 ms). As regards the echocardiographic and dynamic ECG examination, normal data were obtained for both twins which were pratically superposable to those obtained three years before.
Meckel-Gruber Syndrome in One of Nonidentical Twins: Short Case Report
Authors: Juabeh I.I. , Thalji A. , Dudin A.
Published: July 2016

A male twin pair, the result of 34 weeks gestation by dates, 38 weeks by estimation, was delivered at our hospital by normal vaginal delivery on 02.01.87.

The mother is a 27-year old, A,Rh+ healthy school teacher. She was married to her 33-year old, first-degree cousin in 1981. They have no family history of malformed newborns or other inherited diseases.

The first pregnancy of this gravida-four mother was in 1982 and resulted in a full-term, healthy female weighing 3.5 kg. The second pregnancy was in 1984 and resulted in a 36-weeks, alive female with occipital encephalocele, who died 12 hr after birth. It is not known if this newborn had other accompanying congenital anomalies. The third pregnancy was in 1985, and the fetus was aborted at 12 weeks gestation because of anencephaly, which was diagnosed by ultrasound.

The last pregnancy was followed at a private clinic without doing ultrasound. It was not complicated by any illness, drag intake, or X-ray exposure.

After 34 weeks of gestation, male twins were delivered by spontaneous vaginal delivery. Each one had his own placenta and umbilical cord. The first twin was a healthy male weighing 2.4 kg, with Apgar score 7/8, who was discharged home in a good general condition, and was doing well when he was seen at follow up one month later.

The second twin was a male weighing 2.15 kg, and having a length of 48 cm. We was microcephalic with a head circumference of 28 cm.
Central Pockets in Dermatoglyphic Analysis: Classification, Frequency, Twin and Family Data
Authors: Vormittag W. , Weninger M.
Published: July 2016

Central pockets were defined as small, loop-enclosed whorls whose quantitative values must not exceed the third part of the quantitative value of the loop or as small, whorl-like patterns in the core of a loop having at least one curved ridge with its convexity towards the opening of the loop. Applying this classification scheme, the frequency of central pockets was found to be 17.5% in 200 males and 17.0% in 200 females, but was significantly higher in a sample of 21 male and 22 female pairs of MZ twins (33.2% and 34.1%, respectively). Twin as well as family data (94 families with 269 children) pointed to a rather weak hereditary influence upon the formation of central pockets. Rudimentary central pockets occurred in 9.5% of males and 10.0% of females. Since no common genetic basis could be established for central pockets and rudimentary central pockets, the latter should not be scored as central pockets.
Within-Pair Differences in Newborn Twins: Effects of Gender and Gestational Age on Behavior
Authors: Riese Marilyn L.
Published: July 2016

The behavior of 120 full term and 160 preterm newborn twins was assessed in several key areas: Irritability, soothability, reactivity, reinforcement value, and activity level. Infants were assessed during various situations so that aggregate, or summary, scores representing each behavioral area could be obtained. Evaluations were made during a feeding period, an active sleep period, an awake alert period during which orienting and interactional behaviors were observed, a quiet period during which reactivity to stress was observed, and any fussy periods during which irritability and soothability were assessed. Significant within-twin-pair concordance of behavior was obtained for each of the areas of behavior, suggesting the influence of constitutional variables on neonatal behavior. Analysis of these data by sex resulted in significant within-pair concordance of behavior for same-sex but not for opposite-sex twins. The actual ratings on these behaviors differentiated between full term and preterm infants. Increased behavioral deviance was observed with increasing prematurity in the areas of soothability and activity level. The results are discussed in terms of increased risk factors for preterm twins.
Selective Birth in a Case of Twins Discordant for Tay Sachs Disease
Authors: Redwine F.O. , Petres R.E.
Published: July 2016

The authors have performed selective birth in two twin pregnancies in the same patient. The couple's first pregnancy resulted in the birth of a male with Tay Sachs disease: their Pergonal-induced second pregnancy was a twin gestation discordant for Tay Sachs disease. A fetal intracardiac puncture, exsanguination, and fetal intracardiac air embolization were then performed. The patient went into premature labor 9 days later and delivered a normal immature infant, who died, and the macerated cotwin. The third Pergonal-induced pregnancy was a singleton with Tay Sachs disease and the pregnancy was terminated. Their fourth Pergonal-induced pregnancy was a twin gestation discordant for Tay Sachs disease. At 20 weeks gestation, fetal intracardiac air embolization was performed with immediate demise of the affected fetus. The pregnancy was followed closely with ultrasonography and coagulation studies and proceeded to term without complication. A normal female and a fetus papyraceous were delivered by cesarean section.
Case Reports of 16 Sets of Conjoined Twins from a Uganda Hospital
Authors: Zake E.Z.N.
Published: July 2016

During a 10-year period (1971-1980) 16 sets of conjoined twins were delivered in the author's hospital. The incidence of those twins was 1 in 4242 deliveries, 1 in 69 multiple births, and 1 in 139 congenitally malformed babies. All diagnoses were made during labour or at operation and all babies were lost. There were no maternal deaths.
Zygosity Test Based on Growth Measures: A Bayesian Approach
Authors: Rossi C. , Brenci G. , Ziparo R.
Published: July 2016

A statistical index is proposed in order to determine twin zygosity based on weight and height measures and a Bayesian test of hypotheses. Some Roman twin data are analyzed on the basis of the Euclidean distance index, which appears to be the best for an easy calculation and for its genetic interpretation based on the formulation of genetic distance.
Utility of Genetic Markers in the Study of Human Resemblance
Authors: Kimberling W. J. , Goldgar D. E.
Published: July 2016

A method for the estimation of genetic correlations based upon analysis of genetic marker phenotypes is presented. At a given marker locus, the probability of observing a pair of individuals with a specific combination of phenotypes can be expressed as a function of the gene frequencies at that locus and the genetic correlation (R) between that pair. The likelihood of obtaining a sample of n such pairs with their phenotypes at m marker loci can be expressed as a product of nm such functions. From the likelihood function, maximum likelihood estimates of R can be obtained, and hypotheses about R may be tested. A sample of Swedish twin families (61 dizygotic twin pairs, 268 husband-wife pairs, and 164 sib pairs) were analyzed by this method using information from 21 markers. It was found that for the twin pairs, R = 0.458, which was significantly different from the R calculated for sib pairs (R = 0.5 58) but not significantly different from the expected 0.5. For the husband-wife pairs, it was found that R = 0.086, which did differ significantly from the expected value of 0, indicating the presence of nonrandom mating in this population.
A Discordant Case of Monozygotic Twins With Symbrachydactyly
Authors: Shiono Hiroshi , Ogino Toshihiko
Published: July 2016

The case presented here may be the first report of symbrachydactyly in one child of monozygotic twins. Detailed testing of blood groups was performed to confirm zygosity. This case suggests that symbrachydactyly may be caused by intrauterine environmental factors.
Human Behavioral Development and Genetics
Authors: Wilson Ronald S.
Published: July 2016

Behavioral development during childhood is examined in relation to recent concepts and data from evolutionary theory and developmental genetics. The epigenetic framework of Waddington is proposed as a powerful tool for analyzing the progressions in behavior, particularly for recognizing that development involves coordinated pathways of change over time. Many of these pathways appear to depend upon the activity of timed gene-action systems that switch off and on according to a predetermined plan. Behavioral development thus gives expression to the dynamics of preprogrammed change; and in this perspective, behavioral discontinuities may be as strongly rooted in the epigenetic ground plan as the continuities are. The present paper aims to pull together some common themes from different areas that bear on the central issues of behavioral development—the neural foundations, the time course followed, the interplay of maturation and experience, the extent of preorganization furnished by the genetic program, and the adaptive significance of such behaviors in an evolutionary perspective. The final section touches on some hypotheses drawn from developmental neurobiology and developmental genetics that may enrich the analyses of human behavioral development.
A Reappraisal of Perinatal Mortality Factors in Twins
Authors: Puissant F. , Leroy F.
Published: July 2016

During the last 33 years, the perinatal mortality of twins has decreased regularly in our department. When examined by duration of pregnancy, mortality was lowest at 37–38 weeks. Below 38 weeks, fetal loss was paradoxically higher in twins born from multiparae. When delivery occurred beyond 38 weeks, mortality rates were increased, but only differences for primiparous group showed statistical significance. Near-term fetal loss was predominantly due to antepartal intrauterine deaths. Analysis of individual cases indicated that early termination of pregnancy might help prevent near-term stillbirths in twins delivered by primiparae. Efforts should be directed at specific detection of twins threatened by antepartum death.
The Lecithin/Sphingomyelin Ratio in Twin Pregnancies
Authors: Norman R.J. , Joubert S.M.
Published: July 2016

The lecithin/sphingomyelin ratio showed no difference between the two amniotic sacs in 24 multiple pregnancies examined before the onset of labor. Once labor started, however, the L/S ratio was higher in the first sac compared to the second in the six pregnancies where labor had commenced and was somewhat advanced at the time of amniocentesis. Dual-sac amniocentesis is essential during labor when assessment of pulmonary maturity is required, whereas single-sac sampling is adequate before the start of labor.
Kent-Rosanoff Word Association Test: Aged Twins With and Without Dementia
Authors: Bettner Louise G. , Blum June E. , Jarvik Lissy F.
Published: July 2016

As part of a long-range study on mental functioning in old age, 53 twins (mean age 84 years) were given the Kent-Rosanoff Word Association test, a test which measures the cognitive ability to give discrete verbal association to common stimulus words. In general, the results obtained with the aging twins were similar to those previously reported for young adults tested in the early 20th century, nearly 90% of the responses being found in the 1910 Kent-Rosanoff norm tables. Our results are consistent with the trend reported in the literature toward diminished primary responses with advancing age. Unlike reports in the literature, however, the present study detected no sex differences, possibly due to the small sample size (18 men and 35 women). Moreover, Kent-Rosanoff performance was not significantly related to organic brain syndrome, as measured by psychiatric evaluation, Graham-Kendall Memory-for-Designs test, and Stroop-Color-Word test, possibly because most of the twins were diagnosed as having only a “mild” or “moderate” degree of impairment. The intraclass correlations were higher for MZ than DZ twin partners, the differences reaching statistical significance for two scoring categories, primary and unusual responses. Even though the sample was small, only six DZ and 12 MZ pairs, this finding suggests a possible hereditary component in the verbal associative behavior of octogenarians.
Heritability of Systolic Blood Pressure.Analysis of Variance in MZ Twin Parents and Their Children
Authors: Rose R. J. , Fulker D. W. , Miller J. Z. , Grim C. E. , Christian J. C.
Published: July 2016

Systolic blood pressure, standardized for age and sex, was measured in 76 MZ twin pairs and their 341 children. Maximum likelihood estimation of genetical and environmental parameters from the independent parental and offspring ANOVAs indicated a complete absence of both maternal and shared environmental effects, together with a heritability of 63%. These results are shown to be reasonably consistent with those from previous studies.
The Etiology of Human Dizygotic Twinning With Special Reference to Spontaneous Abortions
Authors: Hémon Denis , Berger Colette , Lazar Philippe
Published: July 2016

The comparison of 622 twin and 622 singleton births allowed us to confirm the association of dizygotic twinning with maternal age, parity, and maternal weight and height, as well as the occurrence of unlike-sex twins in the mother's family. It was also shown that none of these associations, except for maternal height, can be explained by the others. Dizygotic twinning was also found to be negatively correlated with previous use of oral contraceptives and with irregularity of menstrual cycle. Finally, the relationship between spontaneous abortion in previous pregnancies and maternal exposure to medical irradiation was investigated.
Relative Cervical Incompetence in Twin Pregnancy. Assessment and Efficacy of Cervical Suture
Authors: Sinha D.P. , Nandakumar V.C. , Brough A.K. , Beebeejaun M.S.
Published: July 2016

A total of 88 women with a twin pregnancy who had elective cervical suture were compared with 76 women with a twin pregnancy who had cervical assessment between the 13th and the 28th weeks of gestation but received no active treatment. The incidence of spontaneous onset of labour before 36 weeks was higher in the cervical suture group, and 53.4% of them sustained cervical damage.
Clinical Management of Twin Pregnancies
Authors: Héluin G. , Bessis Roger , Papiernik E.
Published: July 2016

Early diagnosis and subsequent management of twin pregnancy resulted in a considerable reduction of preterm deliveries (26% vs 61% for late diagnoses).
Delivery in Twin Pregnancy
Authors: Héluin G. , Papiernik E. , Berardi J.C. , Frydman R.
Published: July 2016

Preliminary observations fail to indicate a higher risk to the twin babies as a result of labor induction or Cesarian section, so that a systematic clinical trial will now be possible.
Association of Twin Zygosity With the Mean and Variance of Tooth Size
Authors: Potter Rosario H. Yap , Yu Pao-lo , Christian Joe C.
Published: July 2016

To search for an association of twin zygosity with tooth size, 56 dental variables measured from 65 pairs of twins (43 MZ, 22 DZ) were studied. Results of the t′ test for equality of the means showed no association of zygosity with any of the variables in males or in females. Results of the F′ test for homogeneity of total variances between zygosities showed evidence for unequal total variances in 15 variables in males and 13 in females. Sex influence was further noted on the association of zygosity with the variance of tooth size. Where total variances were unequal, genetic variance estimates differed when only the within-pair mean squares were used and when combined estimates designed to be unbiased by differences in environmental variances were used.
Twin Azygotic Test for the Study of Hereditary Qualitative Traits in Twin Populations
Authors: Gedda L. , Rossi C. , Brenci G.
Published: July 2016

Following previous formulations of a model of qualitative analysis of twin population data independent of zygosity, a new Bayesian approach has been developed. The present model can be applied to any qualitative genetic trait in twin population data, provided no specific source of variation be introduced by the twin condition, and allows not only estimation of the frequencies of mono- and dizygosity as well as the gene frequencies, but also verification of the trait's mode of inheritance.
Variability of Plantar Zygodactylous Triradii in Monozygotic and Dizygotic Twins
Authors: Aue-Hauser G. , Lebioda H. , Szczotka H. , Wytek R.
Published: July 2016

Using a special method, the dermatoglyphics of the plantar interdigital areas of 86 monozygotic and 76 dizygotic Polish twin pairs were obtained. The frequencies of different types of zygodactylous triradii were estimated using a recently published new scheme of classification. The second, third, and fourth interdigital areas were grouped together. The findings indicate a high heritability which suggest that zygodactylous triradii might be used as a valuable genetic marker.
Inbreeding Load in the Newborn of Hyderabad
Authors: Murty J.S. , Jamil Talat
Published: July 2016

The population of Andhra Pradesh has been considered ideal for the study of inbreeding effects in view of its high incidence of consanguinity. Information for the present investigation was obtained from 1,091 consecutive hospital single births to study the genetic load in the newborn in terms of mortality and malformation as a consequence of inbreeding. The nature of consanguinity was examined and the frequency of uncle-niece marriages was found to be lower than in other parts of Andhra Pradesh. The mortality load in the newborn was found to be two lethal equivalents per individual, while the malformation load at birth was half the mortality load.
Sexual Variation in the Fingerprints of Australian Aborigines
Authors: Rao P.D. Prasada
Published: July 2016

Sexual variation in fingerprint types and pattern size, as measured by total ridge counts, has been examined in a sample of 84 Australian aborigines and compared with other populations. As it generally happens in a population, total ridge counts have been found to be higher in males than females on account of (1) the males' higher frequency of whorls and lower frequency of loops, and (2) the males' larger whorl counts. The higher incidence of arches in females than males has also been found to play a role.
Frequency of Thoracoomphalopagus Conjoined Twins in Thailand
Authors: Ubolcholket Siwaporn
Published: July 2016

Twenty-two cases of conjoined twins have been collected in Thailand. The numbers occurring in the various parts of Thailand are listed. No known cases have occurred between the years 1968-1973. The extent of union between the conjoined twins is described and illustrated. Some theories are offered as to etiological factors which might account for the occurrence of conjoined twins.
Heredity of Twinning in Families of Monozygotic Twins
Authors: Gedda L. , Russo O. , Capone M.
Published: July 2016

Whereas the existence of some genetic factor underlying the phenomenon of twinning is almost generally accepted with respect to DZ twins, no such agreement exists with respect to MZ twins. The possible existence of genetic factors underlying MZ twinning has been verified through an analysis of segregation in the sibships of MZ twins and in those of their parents, carried out on a sample of 57 MZ twin pairs (30 M and 27 F). Haldane's a priori method has been applied, considering the sample as obtained through a complete and through an incomplete ascertainment. The results may lead to cautiously confirm the hypothesis of some genetic conditioning of MZ twinning.
Genetic Studies of the Offspring of Identical Twins - A Model for the Analysis of Quantitative Inheritance in Man
Authors: Nance Walter E.
Published: July 2016

In conjunction with full-sib and parental observations, half-sib analysis permits an estimation of the genetic and environmental variance as well as a partitioning of the genetic variance into its additive, dominance and epistatic components. The offspring of identical twins are a unique class of human half-sibs who provide an unusual opportunity to resolve and measure several additional potentially important sources of human variation including maternal effects, the influences of common environmental factors and assortative mating.

The genetic model thus developed for the analysis of quantitative inheritance in man has been applied to the analysis of total ridge count and birth weight, confirming the existence of a major additive genetic effect on ridge count and a significant maternal effect on birth weight.
Death-Discordant Twins A New Method to Evaluate Genetic Factors in Chronic Diseases
Authors: de Faire Ulf , Lundman Torbjorn
Published: July 2016

One of the most important lines of research on unselected large scale twin registries are mortality follow-ups. Death-specific concordance rates have been calculated using different measures of concordance. These estimates are of great importance but they only reflect an “all or-none” classification of the genetic effect. It is suggested that mortality studies could be extended to, and include studies on, death-discordant twins. Such studies combine the advantages from mortality follow-ups on total twin populations with the detailed clinical investigation on subsamples. By examining the surviving cotwins with respect to various traits and supposed risk factors, an opportunity has been provided to study the genetic determination on the development of disease. This approach has been used in a study of ischaemic heart disease (IHD) and its risk factors in a representative subsample from the Swedish Twin Registry.
Heritability Study on Size of the Physiologic Cup of the Optic Nerve Head - A Summary Report
Authors: Schwartz J. T. , Reuling F. H. , Feinleib M.
Published: July 2016

Cupping of the optic nerve head is regarded as one of a triad of diagnostic signs associated with glaucoma. This study was undertaken to assess the role of genetic factors in determining size of the physiologic cup of the normal optic nerve head, as measured by a horizontal cup/disc ratio. This is important to our ultimate understanding of the determinants of pathologic change. Horizontal cup/disc ratio was estimated in a sample of 37 MZ and 26 like-sex DZ twin pairs aged 15 years and older. Differences between MZ and DZ samples with respect to intrapair variance and intraclass correlation coefficient were highly significant. This finding of high heritability for measurements of cup diameter is in contrast to low heritability estimates found in a companion investigation on heritability of the effect of corticosteroids on intraocular pressure.
Heredity and Environmental Factors in the Development of Psychogenic Diseases
Authors: Schepank Heinz
Published: July 2016

Phychoanalytic diagnostic methods and measures have been applied to 50 neurotic twins belonging to 21 MZ and to 16 same-sex and 13 opposite-sex DZ pairs. The 100 subjects consist of 64 adults and 36 children or adolescents. All 100 subjects were personally seen and psychologically examined. The mean intrapair difference of all MZ twin pairs amounts to 3.81 scaling points in a scored degree of severity of the neurosis; that of all DZ pairs to 5.00 points. The distribution of 657 neurotic symptoms in a chi-square table of the 21 MZ and 29 DZ twin pairs shows that 32.7% of the symptons are concordant in the MZ sample, but only 16.7% in the DZ sample. Hereditary influence could be shown in the manifestation of neurotic depressive symptoms, maladaptive oral and aggressive behavior, as well as in schizoid behavior deviations. Hereditary factors play a role in the formation of the neurotic character structure.

Regarding the environmental pathogenic factors, subjects more heavily stressed in early childhood were found, on the whole, more severely neurotic in later life.