bluuebunny/crossref_metadata_2025 huggingface dataset:
Perinatal Morbidity and Mortality Rates in Twin Pregnancies – A 15-Year Review Study from Athens
Authors: Liapis A. E. , Hassiakos D. K. , Panagopoulos P. P.
Published: July 2016

There were 150 deliveries of twin pregnancies over 26 weeks in our hospital. The incidence of twin pregnancies was 1.0% in a population consisting of Greek nationals. Seventy five (50%) were term at delivery whereas 75 (50%) were premature (mean gestational age at delivery 36.5 weeks). The birth weight at delivery ranged from 350 grs to 4,050 grs with mean birth weight for the 1st and 2nd twin of 2,404 grs and 2,384 grs, respectively. One hundred and forty four (48%) neonates had weights between 1,501 to 2,500 grs. Twenty two (9.57%) neonates had weights between 1,501 grs to 2,500 grs. The perinatal mortality when birth weights exceeded 1,500 grs was 7.32%. In total, 186 (62%) newborns were delivered vaginally and 114 (38%) by cesarean section. Forceps were used in 4.33% of the cases and breech extraction was performed in 2.33%. The mode of delivery and perinatal mortality rates were not correlated for both twins (p>0.05). The most common causes of death were hyaline membrane disease (48.5%), immaturity (18.2%), congenital abnormalities (15.1%), septicemia (12.1%) and asphyxia (6.06%). Prematurity seems to constitute the most common cause of perinatal deaths while the mode of delivery found to be irrelevant to perinatal mortality.
Come Nacque l'Istituto Mendel
Authors: Gedda Luigi
Published: July 2016

Nelle aule delle Università di Pavia, Milano e Torino che ho frequentato a motivo dei continui spostamenti della mia famiglia ho trascorso e concluso il mio “curriculum” conseguendo la laurea in Medicina nel 1927 e poi la Libera Docenza in Patologia Speciale Medica nel 1931.

Nel mio trasferimento a Roma ebbi l'intuizione della Genetica studiando i caratteri somatici di una coppia di gemelli identici osservandone la concordanza contemporanea caratteristica ed in particolare la concordanza anche quantitativa di polimorfismi ematici, in particolare delle frazioni del glutatione ematico. Le concordanze nei gemelli monozigotici mi aprirono la strada alla genetica. Questo avvenne nel 1933.

Nel 1938, ebbi occasione di conoscere Madre Luisa Tincani che avendo fondato un Istituto Superiore parificato per religiose si trovava in difficoltà perché avrebbe dovuto rispettare il decreto del Governo fascista sull'insegnamento delle leggi razziali. Ritenni che avrei potuto aggirare l'ostacolo insegnando a quelle religiose le leggi di Mendel che sono il punto di partenza per lo studio di ogni carattere ereditario normale o patologico.

Quel mio corso andò benissimo in quanto insegnai non solo le leggi di Mendel ma conobbi la figura di un grande personaggio sacerdote, confessore dei prigionieri nel carcere dello Spielberg e Abate che, nel giardino del convento conduceva le sue esperienze che ebbero come oggetto principale il pisum sativum. cioè il pisello.

Mentre andavo approfondendo la mia conoscenza dell'Abate agostiniano Gregorio Mendel mi sorprendevo che a Roma non ci fosse nessuna traccia di lui. Di qui nacque l'idea di creare in Roma un Istituto dedicato alla Genetica che portasse il suo nome anche perché questa scienza aveva, nel frattempo, fatto dei passi giganteschi, per cui progettai di costruire nelle adiacenze della Università “La Sapienza” un Istituto che portasse il nome di Mendel (Fig. 1).
Are Differences between Twins a Result of Mutual Rivalry?
Authors: Borg J. G.
Published: July 2016

The sexual index included in the Szondi test makes it possible to define the domains of an individuals “internal sex” or gender – especially the degree of the subject's bisexuality. This index was employed in a comparison between partners reared together in 62 monozygotic and 23 dizygotic pairs of twins. The observed incongruence in 1/3 MZ pairs would not appear to derive totally from errors of measurement. In most of these pairs it is competition which underlies the incongruence seen on the sexual index. It was further observed that the congruence here as in general in female pairs is clearly more marked than in males. A hypothesis was proposed, whereby competition for dominance is a distinctively major-tonality (masculinity) characteristic. The incongruence is more conspicuous among males because males are in general more markedly major-toned than females. This hypothesis was borne out. It is thus necessary here as in general to adopt two sex variables in parallel: external (i.e. matricular) sex and internal sex (gender). It is due to the presence of these competitive pairs that the means and especially deviations of twins' test results will consistently diverge from those in the population at large.
Abstraction Skilfulness in Monozygotic and Dizygotic Twin Pairs
Authors: Nicole S. , Miglio C. Del
Published: July 2016

The computerized version of the Wisconsin Card Sorting Test (WCST) was administered to a sample of 96 subjects (Ss), constituted in equal parts by monozygotic twins (MZ), dizygotic twins (DZ), unique children and couples of “almost contemporary” brothers. The statistic tests (Analysis of principal components, ANOVA) underline, as far as the rapidity to define a category is concerned, a statistically significant difference between DZ and singletons, independently from the fact that the latter may be unique children. A significant difference emerged neither between MZ and singletons, nor between MZ and DZ.
Temperament Development to 30 Months of Age in Discordant Twin Pairs
Authors: Riese M. L.
Published: July 2016

Twins within pairs often have different weights at birth. A difference of 15% or greater is defined as discordance for weight and is considered to place one or both infants at risk. Temperament differences had been found in the neonatal period for full-term discordant cotwins, but not for preterm discordant cotwins, suggesting that continued gestation for discordant twins was a risk variable for early behavior. 30 pairs of fullterm and 17 pairs of preterm discordant pairs were followed at 6, 9, 12, 18, 24, and 30 months of age. Group differences were observed for the longitudinal maintenance of cotwin discordance in physical measures, with preterm cotwins becoming more like each other. In laboratory assessments, temperament differences no longer were observed between the larger and smaller cotwins. Questionnaires indicated that mothers generally did not differentiate between their larger and smaller cotwin children in temperament ratings, except for ratings of mood for the fullterm pairs. Thus, emotionality was the only temperament dimension that differentiated between the fullterm discordant twins both in the neonatal period and at later ages. In the main, it was concluded that the fullterm discordant twins overcame the adverse in-utero influences on early behavioral development.
Genetic and Molecular Studies onOm, a Locus Controlling Mouse Preimplantation Development
Authors: Cohen-Tannoudj M. , Balducci P. , Kress C. , Richoux-Duranthon V. , Renard J.P. , Babinet C.
Published: July 2016

Several lines of evidence have accumulated in recent years indicating that nuclear cytoplasmic interactions play an important role in the formation and fate of the developing mouse embryo. Early nuclear transplantation experiments indicated that the ability of nuclei to direct cleavage after transfer into enucleated zygotes falls abruptly with nuclei from more advanced preimplantation stages [1]. Transcriptional activation of the nuclei, which occurs during the second cell cycle probably precludes the reprogramming of nuclei from later cleavage stages [2]. Thus, when an 8-cell nucleus is transferred to an enucleated zygote, such a reconstituted zygote is blocked at the 2-cell stage. However, when identical 8-cell nuclei were transferred into both blastomeres of enucleated 2-cell embryos, they were able to support development to the blastocyst stage and even gave rise to live offspring [2-4]. This indicated the importance of the cytoplasmic environment for the ability of the incoming nucleus to support development. It should be noted that in these experiments, the nuclear cytoplasmic ratio was also an important factor in determining the development of the reconstituted embryos [2]. Similar observations were also made when monitoring the development of haploid embryos [5]. In another study, Latham and Solter [6] examined the ability of androgenones, obtained by replacing the female pronucleus of a zygote by the male pronucleus, to develop to the blastocyst stage. Androgenones generated from C57B1/6 eggs were found to be much more competent to give rise to blastocysts than were DBA/2 androgenones. However, when androgenones were constructed from (DBA/2×C57B1/6)F1, zygotes (genetic constitution of the embryos will hereafter be indicated with the female parent coming first followed by the male parent), by replacing the DBA/2 female pronucleus with a C57B1/6 pronucleus, they also developed poorly. This was not simply due to the lack of some component in DBA/2 cytoplasm, since the impaired development was also observed when C57B1/6 male pronuclei from pairs of (DBA/2×C57B1/6) F1, were transferred to an enucleated C57B1/6 egg.
Uniparental Disomy and Genome Imprinting: an Overview
Authors: Engel E.
Published: July 2016

The following paper is concerned with potential changes in the normal epigenetic process in a diploid individual, when a chromosome pair or segment is inherited from one parent only, instead of the expected biparental contribution. This aberrant mode of transmission arises from the high rate of gamete aneuploidy in humans. It has received the name uniparental disomy (UPD), and has emerged as an important factor in the new field of nontraditional inheritance, depicted in Table 1.

The following definitions may foster a better understanding of this discussion.

UPDis the inheritance ofbothcopies of a chromosome [or chromosomal segment(s)] from asingleparent, instead of the normal biparental transmission of the pair. Inisodisomy,the two uniparental copies areidentical, being derived from the same parental chromosome. Inheterodisomy, the two uniparental chromosomes aredifferent, being derived from the homologues of a pair.
Medical and Clinical Genetics: Their Roots and Challenge
Authors: Polani P.E.
Published: July 2016

The origins and development of human, medical and clinical genetics are interwoven and yet each of these disciplines follows its own path.

The beginnings of a systematic human genetics can be traced to the middle of the 19th century, but it took human genetics almost 100 years to mature fully and influence medicine. Its origins can be traced to the work of three scientists: Galton, Pearson and Bateson.

In 1865, 6 years after Darwin had published Origin of Species in London, and the year when Mendel's paper, “Experiments on Plant Hybrids”, was published in Brunn, Galton, also in London, set out his first ideas on human heredity. His thinking then developed in two directions. The first laid the foundations for the scientific study of human heredity through biometrics and quantitative genetics. This part of Galton's thinking is summarized in his epitaph: “the dominant idea of his life's work was to measure the influence of heredity on the mental and physical attributes of mankind”.

Galton's other line dealt with the application of heredity through eugenics, a word that Galton coined to signify “well bred”. He wanted, I quote his words: “to produce a highly gifted race of Man by judicious marriage through several generations”. Families of merit should be identified and positively encouraged to breed; conversely, the “ weak could find a welcome … in celebrate monasteries”.
Maternal Uniparental Disomy for Chromosome 14
Authors: Coviello D.A. , Panucci E. , Mantero M.M. , Perfumo C. , Guelfi M. , Borrone C. , Bricarelli F. Dagna
Published: July 2016

A girl carrying a de novo balanced 13-14 robertsonian translocation showed a clinical phenotype with severe hypotonia, hyperextensible joints, frontal bossing, asymmetric face, no mental retardation, severe scoliosis and motor delay. In situ hybridization analysis on chromosome spreads revealed the presence of the two centromeres in the rearranged chromosomes. Molecular analysis on genomic DNA showed the presence in the proposita of two chromosomes 14 of maternal origin and no chromosome 14 from the father indicating a maternal monocentric uniparental disomy for chromosome 14 (mUPD14). Our patient shows several similarities with other reported cases of mUPD14, suggesting imprinting of a region(s) of chromosome 14 and defining a possible mUPD14 Syndrome.
Molecular Analysis of an Extra inv dup(15)(q13) Chromosome in Two Patients with Angelman Syndrome
Authors: Buchholz T. , Schuffenhauer S. , Evans K. , Robson L. , Appleton B. , Smith A.
Published: July 2016

Angelman syndrome (AS) is caused by the loss of function of yet unidentified gene(s) which map within 15q 11-13 and show monoallelic expression from the maternal allele. Lack of the maternal allele(s), due to either a deletion on the maternal chromosome 15 (about 70% of AS patients) or a paternal uniparental disomy (UPD)15 (<5%), are the most common molecular defects in AS. Prader-Willi syndrome (PWS) also maps to proximal 15q, but is caused by the loss of function of paternally expressed gen(s) [1]. Here we describe clinical, cytogenetic and molecular data for two non-related patients with AS who carry a nonmosaic extra cromosome inv dup(15).
Parental Source Effect on Inherited Mutations in the Dystrophin Gene of Mice and Humans
Authors: Kress W. , Grimm T. , Müller C.R. , Keller H. , Bittner R.
Published: July 2016

Skewed X inactivation has been suspected as the genetic cause for some female carriers of Duchenne/Becker muscular dystrophy (DMD/BMD) presenting symptoms [1], as well as in manifesting females in other X-linked recessive diseases. No clear “parental source effect” – a difference in phenotype depending upon transmission of the mutated allele by either the father or the mother – has been observed [Cremer]. To date, most studies in this field have analysed the methylation status of flanking polymorphic sites (a measure of the maintenance of X inactivation and imprinting), not the expression of the causal gene itself.

To test the parental source effect on the protein expression of the dystrophin gene, we have set up crosses of mdx/mdx and mdx/y mice – the well-known DMD animal model [2] with the respective wild-type mice of the same strain (Table 1). The obligate heterozygous F1 females show a mosaic expression of dystrophin in skeletal and cardiac muscle upon immunehistological staining. Because the source of the mutation in the litters is well defined, the mosaic pattern should reflect a parental source effect, if any. Such an effect should also change the level of muscle enzymes in serum and may thus be easily testable in humans, too. Since DMD is genetically lethal in humans, one can test the hypothesis of a parental source effect in BMD families only.
No Evidence for Monoallelic Expression of Gnas and Fourteen Other Genes in the Distal Region of Mouse Chromosome 2
Authors: Williamson C.M. , Dutton E.R. , Abbot C.M. , Beechey C.V. , Ball S.T. , Peters J.
Published: July 2016

Distal chromosome 2 is one of ten regions of the mouse genome subject to parental imprinting. Maternal duplication/paternal deficiency of distal chromosome 2 leads to hypokinetic mice with long flat-sided bodies and arched backs, which fail to suckle and die within a few hours of birth. The reciprocal type, paternal duplication/maternal deficiency, shows an opposite phenotype: the mice have short square bodies and broad flat backs and are distinctly hyperkinetic [1], The region is defined by the breakpoints of two reciprocal translocations, T(2;8)2Wa and T(2;16)28H, is estimated to be about 7.5 Mb in size and shows linkage conservation with human chromosome 20q13. We have tested for monoallelic expression of a number of candidate genes that are either likely or known to lie within the distal imprinting region. These included three-Cebpb, E2f1 and Tc/f4-that express transcription factors, two-Cyp24 and Pck1-that are involved in growth, six-Acra4, Edn3, Kcnb1, Mc3r, Ntsr and Ppgb-where a defect could lead to neurological and probably behavioural problems, three:-Cd40, Plcg1 and Rcad-that are doubtful candidates but whose sequence was available for testing their expression and finally, Gnas, which is our best candidate because there is clinical and biochemical evidence suggesting that its human homologue, GNAS1, is imprinted. On/off expression of each gene was tested by RT-PCR analysis of RNA extracted from tissues of mice with maternal duplication/paternal deficiency and its reciprocal for the distal region of chromosome 2. None of these genes was monoallelically expressed in the appropriate tissues before and after birth, suggesting that they are not imprinted. Evidence for the imprinting of GNAS1 in humans is based on studies of patients with Albright's hereditary osteodystrophy (AHO) who possess a dysfunctional GNAS1 allele. AHO somatic features together-with resistance to parathyroid hormone and other hormones that act via cAMP occur when the defective allele is inherited from the mother whereas AHO somatic features alone occur in paternally transmitted cases [2]. If genomic imprinting regulates Gnas expression in the mouse, then its effect must be specifically confined to hormone-responsive cells.
Eight-Year Follow-up of Cognitive Development in 33 Twin Pairs
Authors: Åkerman B. Alin
Published: July 2016

This is a follow-up study of twins, including 33 twinpairs from the Stockholm area, aiming to study the cognitive development of twins at eight years of age. The twins have been followed at different ages from birth onwards. All children were tested with the Wechsler Intelligence Scale for Children in a Swedish translation (WISC). The WISC test consists of a Verbal and a Performance Scale. There were no significant differences between twin girls and twin boys on these Scales. On the Performance subtests Block Design, Object Assembly, and Coding, however, the twin girls performed significantly better than the twin boys. In comparing cognitive development for twins and singletons, the twin group had somewhat lower average scores than the singletons. Prematurity and low birth weight continued to be related to cognitive development at eight years of age. Also at this age the school teacher completed a questionnaire about the twins social behaviour and some personality traits. There was a relation between one questionnaire factor, a low score of assertiveness, and the mother's negative or ambivalent expectations concerning the twin pregnancy. The twin group with the mother's negative expectations also had significantly lower results on the subtests Comprehension and Coding. Negative mothers had more premature twins than mothers who were positive toward the twin pregnancy.
Self-Awareness in Monozygotic Twins: A Relational Study
Authors: Nicole S. , Del Miglio C.
Published: July 2016

This study considers the replies to a 14-item questionnaire, by 27 monozytogic (MZ) and 38 dizygotic (DZ) pairs. Another sample consisting of 48 sets of parents of twins (24 of whom were MZ and 24 DZ, not necessarily corresponding to the couples of twins actually studied) was used, to answer a questionnaire directly related the one put to the twin pairs. The results of statistical tests performed (canonical correlation and Fisher's discriminant) indicate that only in MZ twins does self-awareness outweigh pair-awareness. This does not seem to be related to any difference between MZ and DZ twins in the education/upbringing received from their parents.
Use of the Systems D1S80, D17S30, ApoB, TC11, VWA, and SE33 for Zygosity Determination - Letter to the Editor
Authors: Scheil H.-G. , Huckenbeck W.
Published: July 2016

The usefulness of PCR systems (D1S80, D17S30, ApoB, TC11, VWA, and SE33) is discussed. The statistical evaluation shows that these systems – together with other systems – are well suited for zygosity testing.
Zygosity as a Risk Factor for Complications and Outcomes of Twin Pregnancy
Authors: Hoskins R.E.
Published: July 2016

All of the recorded twin live births in Washington State birth certificates between 1984 and 1988 were used a retrospective cohort study to determine the risk of zygosity on pregnancy complications and birth outcomes (n = 3458). Relative risks comparing different sex (DS) twins to same sex (SS) twins were corrected to relative risks relating dizygotic (DZ) to monozygotic (MZ) twins, using the Weinberg rule. A higher proportion of DS twin pregnancies (3.5%) than SS pregnancies (1.6%) were complicated by gestational diabetes, resulting in an estimated risk for DZ twin pregnancies relative to MZ pregnancies of 8.6 (95% CI = 3.5-21.0). DZ twin pregnancies were at a lower risk for complications of polyhydraminios (RRDZ∣MZ = 0.2, 95% CI = 0.1-0.4) and of pyelonephritis, (RRDZ∣MZ = 0.3, 95% 0 = 0.1-0.8). MZ twins were more likely to have low birthweight and to have shorter gestations. The proportion of first-born babies of MZ twin pairs who died during their first year was similar to that of first twins of DZ pairs; however, the second-born of MZ twins were more likely to die in infancy than were second-born DZ pairs. First twins of DZ pairs were more likely to die of SIDS (sudden infant death syndrome) than the first of MZ twins (RRDZ∣MZ = 1.5, 95% CI = 0.4-5.1). In contrast, DZ second-born were less likely to die of SIDS than were MZ second-born twins (RRDZ∣MZ = 0.1, 95%CI = 0.1-0.7). DZ twins were less likely to have adverse newborn conditions or malformations. The high risk for gestational diabetes for DZ twin mothers is possibly due to the presence of two placentas which may support the development of greater insulin antagonism than the single placenta in the mother of MZ twins. The reduced risk of DZ relative to MZ twins for selected adverse birth outcomes may result from the increased tendency of MZ twins to be premature.
Seasonal Variation of Twin Births in Washington State
Authors: Dionne C.E. , Söderström M. , Schwartz S. M.
Published: July 2016

Twin births are known to vary across seasons in several countries. It has been hypothesized that this variation may be due to seasonal changes in luminosity leading to pineal gland-mediated multiovulation among susceptible mothers. To describe seasonal variation of twin births in Washington State, all mothers residing in Washington State who gave birth to both a pair of twins and a singleton baby between 1984-1990 (n = 1168) were identified through linkage of computerized State birth certificates. Using a “matched-on-mother” case-control design, the estimated month of conception of twin gestations (the “case” events) were compared to that for their singleton siblings (the “control” events) to determine their relative occurrence during periods of high vs low sunlight in accordance with local climatological data. For the study population as a whole, there was only a slight tendency for twins to have been conceived during the period of high sunlight compared to their singleton siblings (OR = 1.3, 95% C.I. = 1.0-1.7). When stratified by concordant-sex vs discordant-sex, however, more discordant-sex twin pairs were conceived during the light period than corresponding singletons (OR = 1.7, 95% C.I. = 1.0-2.8), whereas no association was found for concordant-sex twins (OR =1.1, 95% C.I. =0.8-1.6). The presence of an association only among discordant-sex twins, all of whom are dizygotic, is consistent with the hypothesis that exposure to sunlight may stimulate multiple ovulation, and thus increase the incidence of twin gestations among twin-prone mothers.
The Influence of Birth Order and Presentation on Intrauterine Growth of Twins
Authors: Blickstein I. , Namir R. , Weissman A. , Diamant Y.
Published: July 2016

In order to evaluate the influence of birth order and fetal presentation on antenatal growth of twins we conducted a comparison of prospective measurements of five fetal biometric indices in 50 vertex-vertex and 47 vertex-breech twins. We compared (a) twin A to twin B in both groups; (b) the second and (c) the first twins of both groups. Both groups had similar maternal and neonatal characteristics. The growth curves of the twins were also very similar except for three significant (p<0.05) deviations: (a) Twin A of the vertex-vertex group, had larger femur length (FL) at 18-19 weeks, abdominal circumference (AC) and estimated fetal weight (EFW) at 29 weeks, and EFW measurements at 36 weeks, (b) Second breech twins, compared to their second vertex cohorts, had significantly smaller biparietal diameter (BPD), head circumference (HC) and FL at 18-19 weeks, BPD and HC at 29 weeks, and EFW at 37 weeks, (c) First twins of the vertex-breech group, as compared to first twins of the vertex-vertex group, had significantly smaller BPD and AC at 18-19 weeks, FL and AC at 21-22 and 29 weeks, FL at 31 weeks, and EFW at 27-28 and 36 weeks' gestation. We concluded that significantly different sonographic fetal indices may be measured at about 20 and 30 weeks' gestation, but not later. An adaptive mechanism attributed to fetal presentation is suggested to explain similar birthweights in spite of these antepartum differences.
Breathing Patterns of Monozygous Twins during Behavioural Tasks
Authors: Shea S.A. , Dinh T. Pham , Hamilton R.D. , Guz A. , Benchetrit G.
Published: July 2016

To better understand behavioural and genetic influences upon breathing, the breathing patterns of 8 pairs of monozygous (MZ) twins were measured under 4 behavioural conditions; relaxed without standardisation; eyes closed; eyes open; and reading. Breathing was quantified by inspiratory and expiratory durations (TI, TE), tidal volume (VT) and derived variables. Airflow shape was normalised and quantified using 8 dimensions. Reading caused breathing to increase by > 500 ml/min compared to the other four conditions. Differences in breathing between combinations of two conditions were compared by testing whether the differences within an individual were smaller than the differences between random pairs of individuals from the same 16 subjects. For almost all respiratory variables, and whatever the behavioural condition, there were highly significant similarities within an individual (p < 0.00025 on 32/80 comparisons). Under each condition, the differences within MZ twin-pairs were compared to the differences within random-pairs from the same subject population. There were highly significant similarities within twin-pairs for the airflow shape across all conditions. However, TI, TE and VT failed to consistently show significant similarities within twin pairs. Hence, an individual's airflow shape appears to be a fundamental characteristic which is conserved when behavioural condition and level of ventilation changes. Further, MZ twins have similar airflow shapes – whatever the behavioural situation. Hence, behavioural influences upon airflow shape act upon monozygous twin pairs in similar ways, or such influences were negligible under the conditions of the present study.
Monozygotic Twins with Discordant Sex
Authors: Kurosawa K. , Kuromaru R. , Imaizumi K. , Nakamura Y. , Ishikawa F. , Ueda K. , Kuroki Y.
Published: July 2016

A nine-year-old girl with short stature was referred to the department of pediatrics at Kyushu University. The clinical diagnosis was Turner syndrome; karyotypic analysis performed on peripheral blood, using GTG techniques, demonstrated a 45,X/47,XYY (17:83) mosaicism. Her twin brother, a phenotypically normal male, had the same karyotype; 45,X/47,XYY (3:97) on peripheral blood. Their skin fibroblast karyotypes showed the same mosaicism, ie. 45,X/47,XYY (41:59 and 31:69 respectively). On eleven biochemical genetic markers the twin pair were concordant, thus the likelihood of monozygosity was 0.99527034. In addition, the analysis of variable number of tandem repeat (VNTR) markers revealed the likelihood of monozygosity to be 0.99944386. The most plausible explanation of the X/XYY mosaicism was nondisjunction of the Y in the first cleavage division of the 46,XY zygote. A disproportionate rate of cell populations with 45,X and 47.XYY in the twinning process of the X/XYY embryo, especially in the germ lines, would result in discordant sex in twin pairs.
President's Address: Twins and Genetic Studies of Man
Authors: Inouye E.
Published: July 2016

The International Society for Twin Studies is a unique organization. It is unique in the status of members composing the Society. In addition to specialists of science and medicine we have non-specialist members including twins and their families, all enjoying excellent collaboration in undertaking research and related activities of common interest. This kind of collaboration is very important for academic societies, particularly for those devoting themselves to the studies of man. We aim at a better understanding of man; our purpose is to learn more about ourselves. This activity is not a monopoly of specialists. Our achievements should also be shared by lay people. ISTS can serve as a model for academic societies aiming at the studies of man. Science has the solid ground of logos. At the same time, we realize that the accomplishments of highly specialized science should be reevaluated in the light of human values. I am inclined to believe that our task is to integrate the logos of scientists and ethos of the public into one.

The purpose of twin studies is two-fold; studying multiple birth phenomena per se, and making inquiry into the genetic and environmental sources of human variation. The latter task was initiated by a number of pioneers in the early twentieth century. At that time, however, genetic studies of man including twin studies remained largely descriptive. We could not, and still cannot, perform genetic experiments on human individuals and populations, and the methodology available was limited to observation of a character presented in pedigree members and twins. However, despite the limitation of methodology, classical pedigree analysis has permitted us to accumulate a large amount of data on normal hereditary traits and genetic diseases, or more precisely, simple Mendelian characters.
Perinatal Management of Twin Pregnancy
Authors: Fuchi I. , Okumra Y. , Noda K.
Published: July 2016

Of 104 cases, 38 (ie, 36.53%) experienced premature delivery (controls: 4.32%). In instances of threatened premature delivery, 28 cases (26.92%) underwent ligation of the cervix. EPH gestosis occurred in 62 cases - a high incidence rate of 59.61% (controls: 12.9%). Forty-nine cases (47.11%) were complicated by anemia (controls: 8.36%). There were 57 cases of SFD infants, again a high 27.40% incidence rate (controls: 5.94%). Apgar scores of 7 or less at 1 minute after birth indicated that of the 208 neonates, the second-born twin only in 20 cases (9.61%); both infants in 14 cases (6.73%); and, the first-born only in 3 cases (1.44%), developed asphyxia neonatorum. Given the high incidence of premature and immature infants in cases of twins, caution should be employed against threatened premature delivery from around the 28th week of gestation onwards. Ligation of the cervix with ritodrine administration should be performed following admission to hospital, and EPH gestosis, anemia and IUGR should be carefully monitored.
A Twin Study Approach Towards Understanding Genetic Contributions to Body Size and Metabolic Rate
Authors: Hewitt J.K. , Stunkard A.J. , Carroll D. , Sims J. , Turner J.R.
Published: July 2016

The genetic and environmental determinants of a brief assessment of metabolic rate at rest and under psychological stress were studied in 40 pairs of monozygotic and 40 pairs of dizygotic young adult male twins. Height, weight and age were employed as covariates. Univariate analyses showed a high heritability for height and weight and moderate heritability for metabolic rate. Classical twin analyses and multivariate genetic modeling indicated that genetic influences on resting metabolic rate were entirely explained by body weight: there was no independent genetic contribution to resting metabolic rate. Metabolic rate under psychological stress, on the other hand, showed a significant genetic effect. The exponent (3/4) in the power function relating body weight to resting metabolic rate was the same as that found in a wide variety of animal species, a value that has been proposed as defining a body weight set point. We speculate that an adult body weight set point is genetically transmitted. Independent genetic effects on resting metabolic rate would be observed only when the normal equilibrium between body weight and metabolic rate is unbalanced during development, aging or disease. The study illustrates the use of multivariate genetic analyses of twin data which may be readily applied to widely used metabolic rate assessments.
The Estimation of Probandwise Concordance in Twins: The Effect of Unequal Ascertainment
Authors: Kendler K.S. , Eaves L.J.
Published: July 2016

This report examines the impact of two major kinds of unequal ascertainment on the estimation of true probandwise concordance (Cpbt) in twin studies: 1) concordance-dependent – where the ascertainment rate differs in affected members of concordant vs discordant pairs, and 2) non-independent – where ascertainment rates differ in affected members of concordant pairs where the cotwin has vs has not been ascertained. Concordance-dependent ascertainment is easily modeled algebraically; non-independent ascertainment is more complex and we here propose a model based on survival analysis. Overall, concordance-dependent ascertainment produces greater bias in estimates of probandwise concordance than does non-independent ascertainment. The bias introduced by concordance-dependent ascertainment is greatest when Cpbt is low and/or when the ascertainment rate for twins in concordant pairs is low. The bias introduced by non-independent ascertainment is greatest when Cpbt is high and/or when the ascertainment probability for an affected twin in a concordant pair where the cotwin has already been ascertained approaches unity. The impact of concordance-dependent and non-independent ascertainment on estimates of heritability and common environment is examined. Correction terms to estimate Cpbt in the presence of concordance-dependent and/or non-independent ascertainment are presented.
Conjoined Twins in Hungary, 1970-1986
Authors: Métneki J. , Czeizel A.
Published: July 2016

The total prevalence of conjoined twins (birth + prenatally diagnosed) was 1:68,000 in the study of 1970-1986. Symmetrical cases (the so-called Siamese twins) have an obvious predominance (92.3%). Associated major malformations occurred in 80% of conjoined twins and more than 1/5 were discordant. The surviving time of liveborn conjoined twin sets was not more than two days except in two surgically successfully separated pairs. The family study did not indicate a higher recurrence risk. The case group was compared to two control groups and it appeared that the periconceptional use of oral contraception and ovulation induction were mentioned more frequently in pregnancies resulting in conjoined twins.
Does the Respiratory Distress Syndrome in Twins and Singletons Run Different Risks of Persistent Ductus Arteriosus?
Authors: Zanardo V. , Foti P. , Trevisanuto D. , Zambon P. , Stellin G. , Milanesi O.
Published: July 2016

The incidence and evolution of patent ductus arteriosus (PDA) was evaluated in twins and preterm singletons with birth weight ≤ 1750 g admitted to our Department in 1987 for respiratory distress syndrome (RDS). Screening by echocardiography and Doppler-flow studies (AT MK 600) was performed on the third day of life. Out of 91 neonates who needed intubation and ventilation during this 12-month period (23.8% of admissions), 40 weighed less than 1750 g and of these 40, 14 were twins (35%). Hemodynamically significant PDA was documented in 13 patients; of these, only 5 were preterm singletons and 8 were twins. Two twins weighing < 1000 g received no therapy for ductus closure; one ductus closed spontaneously, the other had an early demise. Three twins and 2 preterm singletons received indomethacin; one of the twins needed a second cycle for definitive ductus closure. Three twins and three preterm singletons underwent surgery, while one twin died on the 10th postoperative day. Screening and early therapy of PDA during RDS could be of great clinical importance. Twinning seems to play a role in the incidence and evolution of PDA and this needs to be evaluated in further studies.
Congenital Anomalies in Twins in Northern Ireland. III: Anomalies of the Cardiovascular System, 1974-1978
Authors: Little J. , Nevin N.C.
Published: July 2016

Rates of congenital anomalies of the cardiovascular system were compared between twins and singletons in a population-based study in Northern Ireland during the period 1974-1978. Multiple sources of ascertainment were used. As in previous studies, the rate of anomalies of the cardiovascular system in twins (91.0/10,000) was higher than the rate in singletons (66.4/10,000). The excess was confined to twins from pairs of like sex and, in the main, anomalies of the circulatory system other than of the heart itself were involved. Problems in the interpretation of this excess are discussed. No twins were concordant for congenital cardiovascular anomalies of any type.
Stillbirth Rate and Weight at Birth of Quintuplets in Japan
Authors: Imaizumi Yoko
Published: July 2016

Nation-wide data in Japan on births and prenatal deaths of 16 sets of quintuplets during 1974-1985 were analysed. Among the 16 sets, 3 sets were liveborn, 8 were stillborn, and 5 were mixed, with a stillbirth rate of 0.64 (51/80). Effects of sex, maternal age and birth order on the stillbirth rate were not considered because of the small sample size. Effects of gestational age and birthweight on stillbirth rate were also examined. The mean weight of the 40 quintuplet individuals was 1,048 g.
President's Opening Address: Twin Study Today
Authors: Gedda L.
Published: July 2016

I wish to thank Professor Paolo Durand, Director of the International Centre of Paediatric Genetics at the Mendel Institute, for his kind words and I particularly thank him for having proposed this celebration to mark the 40th anniversary of the foundation of the Institute.

Somewhat audaciously, I borrow a metaphor when I say that the real foundation stone of the Mendel Institute is the book, “The Study of Twins” here on the bookrest [Fig. 1]. This rather large volume carries works I had collected and developed in Rome over the previous years. In the main, it relates to clinical research work which for me began in an orphanage, not too far away from here on via Nomentana, where I encountered a pair of identical twin brothers, Romolo and Remo [Fig. 2]. The boys were so alike physically that I constantly confused the two and it was this experience that drew my attention to the twinning phenomenon. The book also contains a bibliographic list of over 7,900 studies carried out on the subject of twins. One of the first, of course, is that of Darwin's cousin, Francis Galton and another example from a later period is that of Chiarugi, the Florentine anatomist.

Published in 1951, “The Study of Twins” provoked such overwhelming interest in the medical world that it led me to vigorously promote two initiatives which began to take shape the following year. In 1952 the first issue of the journal “Acta Geneticae Medicae et Gemellologiae” was published and the construction of the Gregor Mendel Institute of Medical Genetics and Gemellology got under way to be finally inaugurated on 6 September 1953. One of the earliest and certainly most important figures in establishing the Institute is here with us today, Dr. Ildo Avetta, the Roman architect who designed the building. Let me take this opportunity to thank him once again for his brilliant work which has drawn the attention and admiration of many over the years.

Here, before you, is the complete 40-volume series of Acta Geneticae Medicae et Gemellologiae from its birth to date. [Fig. 1].
The Epidemiology of Multiple Pregnancies
Authors: Parazzini F. , Villa A. , Moroni S. , Tozzi L. , Restelli S.
Published: July 2016

Over the last decades the frequency of multiple births has been on the decline in most developed countries. This trend, however, has been restricted to dizygotic twins, while monozygotic rates have remained stable or risen slowly. In more recent years, however, the fall in multiple dizygotic birth rates has ceased and a slight increase is observed. This trend and the increased frequency of triplets or higher-order births, registered from the early 1980s onwards, are essentially related to treatments for infertility. No single risk factor, such as maternal age, parity, oral contraceptive use, or declining fertility rates can explain the overall declining trends. In this paper we review the descriptive epidemiology and the main risk factors for multiple pregnancies.
Paediatric Care of Twins
Authors: Bryan E.M.
Published: July 2016

For many parents, the joy of having twins and triplets is reduced by the unexpected emotional as well as physical and financial stresses which they experience with children who may suffer from prematurity and low birthweight, and who have a higher risk of language delay and disability. Paediatric care should start from the time of ultrasound diagnosis. The Multiple Births Foundation holds regular meetings for expectant parents. Twins Clinics are held in three centres in the UK as well as three special clinics (Growth, Supertwins and Bereavement), where families may discuss problems relating to the twinship as well as sharing their experiences with parent volunteers.
The National Academy of Sciences – National Research Council Veteran Twin Registry
Authors: Braun M.M. , Haupt R. , Caporaso N.E.
Published: July 2016

With recent advances in molecular biology and genetics, cohorts such as the National Academy of Sciences-National Research Council (NAS-NRC) Twin Registry may become of increasing importance. This paper outlines the creation and history of the NAS-NRC Twin Registry, methodologies utilized for analysis of twin data, studies that have been completed or are underway, and possible future types of studies.
Idrope Fetale non Immunologia e Gravidanze Gemellari
Authors: Noia G. , Santis M. De , Neri L. , Serraino A. , Storti S. , Gozzo M.L. , Maniccia E. , Caruso A.
Published: July 2016

Presso il Centro di Diagnosi Prenatale all'Università Cattolica del Sacro Cuore di Roma, sono state osservate 95 pazienti con gravidanza complicata da idrope fetale non immunologica. Nove pazienti presentavano una gravidanza gemellare. La sopravvivenza dei 95 feti osservati è stata del 27.7%. Nessun feto gemellare idropico è sopravvissuto. Nei 9 casi di gravidanza gemellare è stato possibile diagnosticare ecograficamente una placenta monocoriale in 6 casi e monoamniotica in 3 casi. La causa dell'idrope fetale è stata riferita in 3 casi a trasfusione feto-fetale; in 2 casi a cardiopatia fetale ed 1 caso a malformazione genito-urinaria e 3 casi di n.d.d. La morte del feto idropico è avvenuta tra la 21a e la 35a settimana di gravidanza. Dei feti gemellari non idropici la sopravvivenza è stata del 57.1% (4 su 7).

Otto delle gravidanze gemellari sono state osservate prima del 1988, epoca in cui nella nostra Istituzione, non era possibile un approccio diagnostico e terapeutico intrava-scolare mediante cordocentesi. Tale possibilità diagnostica e terapeutica può con molta probabilità migliorare la sopravvivenza dei feti idropici nelle gravidanze gemellari come avvenuta nelle gravidanze singole, dove è passata dal 25% (1980-88) al 36.8% (1988-93).
Emodinamica Intracardiaca ed Extracardiaca nei Gemelli con Crescita Discordante
Authors: Capponi A. , Rizzo G. , Cacciatore C. , Romanini E. , Arduini D. , Romanini C.
Published: July 2016

La presenza di crescita discordante di un gemello si associa con una aumentata mortalità e morbilità perinatale. Le cause della scarsa crescita di un gemello possono essere multiple. I risultati apparsi in letteratura sulla velocimetria Doppler in questi casi sono discordanti.

Obiettivi: valutare l'emodinamica fetale mediante velocimetria Doppler in gravidanze gemellari complicate da crescita discordante di un gemello secondarie a due differenti eziologie a) insufficienza uteroplacentare b) twin-to-twin transfusione syndrome (TTTs).

Disegno dello studio: sono state selezionate retrospettivamente 12 gravidanze gemellari biamniotiche bicoriali complicate da ritardo di crescita di un gemello che ha sviluppato nel corso della gravidanza decelerazioni tardive (gruppo da insufficienza uteroplacentare) e 10 gravidanze gemellari monocoriali e biamniotiche con conferma postnatale di TTTs. Si sono eseguite misurazioni seriate a livello dei vasi periferici arteriosi fetali, a livello intracardiaco e dei vasi venosi fetali. La differenza tra i valori assoluti tra i due gemelli (delta) è stata quindi calcolata.

Risultati: nelle gravidanze gemellari con insufficienza uteroplacentare si è assistito ad un aumento progressivo del valore delta in tutti i distretti vascolari indagati che raggiunge valori massimi in prossimità dell'insorgenza delle decelerazioni tardive. Nelle gravidanze gemellari complicate da TTTs il valore delta non dimostra variazioni significative nei vasi periferici arteriosi. A livello intracardiaco e venoso modificazioni si sono evidenziate solo al momento dell'ultima registrazione precedente al parto.

Conclusioni: la velocimetria Doppler permette di identificare i gemelli con crescita discordante secondaria ad insufficienza uteroplacentare. In questi feti è possibile eseguire un monitoraggio longitudinale delle loro condizioni emodinamiche. In caso di TTTs il significato della velocimetria Doppler appare limitato.
Le Cardiopatie Congenite nei Gemelli
Authors: Digilio M.C. , Giannotti A. , Marino B. , Dallapiccola B.
Published: July 2016

Le cardiopatie congenite (CC) isolate sono patologie malformative a prevalente eziologia multifattoriale. Studi epidemiologici su coppie di gemelli mono e dizigoti hanno contribuito a chiarire l'importanza relativa delle componenti genetica e ambientale nella patogenesi delle CC. Nel periodo gennaio 1992-dicembre 1993, sono state valutate presso il nostro centro 24 coppie di gemelli con almeno un componente affetto da CC. In 15 casi si trattava di gemelli dizigoti, in 9 di monozigoti. Sono stati esclusi pazienti con CC inclusa in sindrome cromosomica o mendeliana. Entrambi i componenti delle coppie sono stati sottoposti ad accertamenti cardiologici (valutazione clinica, elettrocardiogramma, ecocardiografia). Le CC osservate sono rappresentate da Tetralogia di Fallot, stenosi polmonare con difetto interatriale, difetto interventricolare, canale atrioventricolare, stenosi aortica, coartazione aortica, trasposizione delle grandi arterie, ritorno venoso anomalo polmonare. L'analisi dei risultati ha mostrato presenza di CC in entrambi i componenti della coppia in 1/15 (7%) dei gemelli dizigoti e in 3/9 (33%) dei gemelli monozigoti. Nel caso della coppia dizigote un gemello è affetto da Tetralogia di Fallot, l'altro da ventricolo unico con atresia della polmonare. Nelle coppie monozigoti con entrambi i componenti affetti da CC, la lesione è concordante in tutti i casi (Tetralogia di Fallot in due casi e stenosi polmonare con difetto interatriale in un caso). La maggiore percentuale di concordanza per presenza di CC nelle coppie di gemelli monozigoti rispetto a quelli dizigoti dimostra l'importanza dei fattori genetici nell'eziologia delle CC. La componente genetica non è però esclusiva ed una signrficativa interazione genetico-ambientale giustifica il riscontro di concordanza per CC solo nel 30% dei gemelli monozigoti.