JOURNAL OF INTERNAL MEDICINE, Issue 5 2003
R. J. F. Loos
Abstract., Loos RJF, Bouchard C (Human Genomics Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA, USA). Obesity , is it a genetic disorder? (Review). J Intern Med 2003; 254: 401,425. Obesity is one of the most pressing problems in the industrialized world. Twin, adoption and family studies have shown that genetic factors play a significant role in the pathogenesis of obesity. Rare mutations in humans and model organisms have provided insights into the pathways involved in body weight regulation. Studies of candidate genes indicate that some of the genes involved in pathways regulating energy expenditure and food intake may play a role in the predisposition to obesity. Amongst these genes, sequence variations in the adrenergic receptors, uncoupling proteins, peroxisome proliferator-activated receptor, and the leptin receptor genes are of particular relevance. Results that have been replicated in at least three genome-wide scans suggest that key genes are located on chromosomes 2p, 3q, 5p, 6p, 7q, 10p, 11q, 17p and 20q. We conclude that the currently available evidence suggests four levels of genetic determination of obesity: genetic obesity, strong genetic predisposition, slight genetic predisposition, and genetically resistant. This growing body of research may help in the development of anti-obesity agents and perhaps genetic tests to predict the risk for obesity. [source]

The Role of Socioregional Factors in Moderating Genetic Influences on Early Adolescent Behavior Problems and Alcohol Use

ALCOHOLISM, Issue 10 2009
Danielle M. Dick
Background:, Twin and family studies have demonstrated that adolescent alcohol use and behavior problems are influenced by a combination of genetic and environmental factors. More recently, studies have begun to investigate how genetic and environmental influences may interact, with efforts underway to identify specific environmental variables that moderate the expression of genetic predispositions. Previously, we have reported that community-level factors, including urban/rural residency, migration rates, and prevalence of young adults, moderate the importance of genetic effects on alcohol use in late adolescence (ages 16 to 18). Here, we extend these findings to test for moderating effects of these socioregional factors on alcohol use and behavior problems assessed in a younger sample of adolescent Finnish twins. Methods:, Using data from the population-based Finnish twin study, FinnTwin12, biometric twin models were fit to data on >1,400 twin pairs to examine the significance of each of the socioregional moderating variables on alcohol use measured at age 14, and behavior problems, measured at age 12. Results:, We find no evidence of a moderating role of these socioregional variables on alcohol use; however, there was significant moderation of genetic influences on behavior problems, with effects limited to girls. Genetic influences assumed greater importance in urban settings, communities with greater migration, and communities with a higher percentage of slightly older adolescents. Conclusions:, The moderation effects observed on behavior problems in early adolescence paralleled the effects found on alcohol use late in adolescence in an independent sample, providing further support for the idea that behavior problems may represent an earlier manifestation of the predisposition to subsequent alcohol problems. Our findings also support the growing body of evidence suggesting that females may be more susceptible to a variety of environmental influences than males. [source]

Twin,twin transfusion syndrome: mathematical modelling

PRENATAL DIAGNOSIS, Issue 4 2008
Jeroen P. H. M. van den Wijngaard
Abstract Twin,twin transfusion syndrome (TTTS) represents a pregnancy complication with a high risk for perinatal mortality and postnatal morbidity. Mathematical models have been utilized to examine the mechanisms of disease and potential treatment modalities. We developed four consecutive models based on pathophysiology mechanisms. Conceptually, these models remained simple, but with increased complexity in details. We present our models tutorially with the necessary equations expressed in words. The aetiology of TTTS was related to AV anastomoses from donor to recipient and their growth commensurate with placental growth. We assessed that natural growth of placenta and foetuses causes the diameter and length of the AV, as well as the AV's pressure gradient, to increase proportional to gestational age. The AV transfusion then increases faster than natural foetal growth. A progressively increasing discordance subsequently develops, not compensated for by foetal growth. A simulation is performed to show how this discordance in blood volumetric development causes successive discordances in other functions, particularly renal, circulatory, and cardio-vascular, resulting in disease progression to the various stages of TTTS. In conclusion, mathematical modelling of TTTS has provided an understanding of the sequence of events that leads to the various presentations of TTTS stages as well as the efficacy of therapies. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Application of QF-PCR for the prenatal assessment of discordant monozygotic twins for fetal sex

PRENATAL DIAGNOSIS, Issue 7 2007
F. J. Fernández-Martínez
Abstract Objective To establish the utility of quantitative fluorescent polymerase chain reaction (QF-PCR) in order to determine the zygosity of multiple pregnancies, as well as to define the origin of the most frequent aneuploidies in amniotic fluid samples. Methods We describe the case of a monochorionic (MC) diamniotic (DA) pregnancy with phenotypically discordant twins (nuchal cystic hygroma and non-immune hydrops in twin A and no anomalies in twin B). QF-PCR was performed for rapid prenatal diagnosis in uncultured amniocytes and subsequently in cultured cells. Polymorphic markers for chromosomes X, Y, 13, 18 and 21 were used for determination of zygosity as well as sex chromosome aneuploidy. Results Twin A showed a Turner Syndrome (TS) mosaicism pattern by QF-PCR in uncultured amniocytes. The monozygotic origin of the pregnancy was determined. Interphase fluorescence in situ hybridization (I-FISH) in this sample showed a mosaicism X0/XY (83/17%). Cytogenetic analysis revealed a 45,X0 karyotype in twin A and a 46,XY karyotype in twin B. Conclusions QF-PCR is a reliable tool for the determination of the zygosity independently of the chorionicity and the fetal sex in case of twin pregnancy. Testing both direct and cultured cells can provide useful results for genetic counselling in chromosomal mosaicisms. Copyright © 2007 John Wiley & Sons, Ltd. [source]

SHORT COMMUNICATION: History of Incidence of Autoimmune and Oncological Diseases in Identical Female Twins

AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 6 2009
Z. Ulcova-Gallova
Problem, The aim of study was to investigate identical female twins born in 1977 suffered from autoimmune diseases (twin A , Sjogren's syndrome, and twin B , systemic lupus erythematosus). Method of study, It was refer retrospective analysis of both sisters suffered beside autoimmune alterations (Sjogren's syndrome and systemic lupus erythematosus) also from gynecological diseases (twin A , praecancerosis of cervix uteri, twin B , carcinoma vaginae). Results, Relationships between disease activities and severities in the female twins were similar and the treatments were directed according to clinical symptoms and laboratory results. Dramatic change, unfortunately, occurred with twin B. The reason may be the association between SLE activity (lupus nephritis), hematological complication (leukopenia) and oncological vaginal recidivation. Conclusion, Association between autoimmune disease and gynecological cancer (or praecancerosis) is major risk than without immunology deviation. Twin A is periodically gynecologically observed. [source]

Fulminant Wilson's Disease Requiring Liver Transplantation in One Monozygotic Twin Despite Identical Genetic Mutation

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2010
K. M. Kegley
Acute decompensated Wilson's disease (WD) that presents as fulminant hepatic failure carries significant mortality without hepatic replacement. The abnormal gene implicated in WD, ATP7B, has been mapped to chromosome 13, and leads to decreased passage of copper from hepatocytes to bile. Excess copper accumulation exceeds hepatocyte storage capacity resulting in intracellular necrosis, apoptosis and cell death in various organs of the body. The hepatic injury induced by the abnormal accumulation of copper in WD has variable presentation such as acute hepatitis, rapid hepatic deterioration resembling fulminant hepatic failure, or as progressive chronic liver disease in the form of chronic active hepatitis or cirrhosis. There are reports in the literature describing monozygotic (identical) twins with similar hepatic progression requiring liver transplantation, however, with different neurological outcome after transplant. We report a case of one monozygotic twin presenting with acute liver failure requiring emergent liver transplantation while the other twin presented with mild liver disease, when both shared an identical genetic mutation. [source]

Twins and cerebral palsy

ACTA PAEDIATRICA, Issue 2001
POD Pharoah
In a national follow-up study of twin births, monozygous compared with dizygous twins were at significantly increased for both to die in utero, one to die in utero and the co-twin to die in infancy, or both to be livebirths but both die in infancy. The prevalence of cerebral palsy among survivors of a co-twin fetal death was 80.2 and other cerebral impairment was 107.0 per 1000. Many apparently singleton cases of cerebral palsy and impairment may be due to fetal death of a twin that has not been recognized or has been recognized but not registered. [source]

Craniorachischisis and Heterotaxia with Heart Disease in Twins: Link or Change Nature?

CONGENITAL HEART DISEASE, Issue 5 2010
Sebastiano Bianca MD
ABSTRACT Craniorachischisis is a rare neural tube defect in which both acrania and a complete schisis of the vertebral column are present. Heterotaxy results from failure to establish normal left,right asymmetry during embryonic development and is characterized by a variable group of congenital anomalies that include complex cardiac malformations and situs inversus or situs ambiguous. We report a diamniotic twin pregnancy with two malformed fetuses affected one by craniorachischisis and the other by heterotaxya with paired right-sided viscera, asplenia, and complex congenital heart disease. The occurrence of severe congenital anomalies in both members of the twin pair implies a strong influence of genetic factors. At present, the genetic basis determining the different phenotypes observed in our twins is unknown. Our case with the simultaneous presence of both midline and laterality defects in twins supports the hypothesis that the midline plays a critical role in establishing left,right asymmetry in the body and that a mutation in a gene responsible for both heterotaxy and midline defects may be strongly supposed. [source]

Physical activity in adolescence and smoking in young adulthood: a prospective twin cohort study

ADDICTION, Issue 7 2007
Urho M. Kujala
ABSTRACT Aims To control for familial confounds, we studied the association between adolescent physical activity and later smoking in twin siblings discordant for their baseline physical activity. Design and measurements In this prospective population-based twin study, we asked whether persistent physical activity/inactivity in adolescence (assessed at 16, 17 and 18.5 years) predicted questionnaire-reported daily smoking at ages 22,27. Twins who, on the three baseline questionnaires, consistently reported frequent leisure physical activity (more than three times weekly) were classified as persistent exercisers, those who exercised less than three times monthly were called persistently inactive, others were occasional exercisers. Setting Finland. Participants A total of 4240 individuals, including 1870 twin pairs. Findings In analyses of individual twins, compared to persistent activity, persistent physical inactivity predicted increased risk of daily smoking (age- and sex-adjusted odds ratio 5.53, 95% confidence interval 3.88,7.88, P < 0.001). The risk remained elevated even after excluding all those who had smoked 50 cigarettes or more life-time at baseline and adjusted for educational level in adolescence. In within-pair analyses compared to the active members of discordant twin pairs, the physically inactive co-twins had increased risk of future daily smoking (sex-adjusted odds ratio 3.39, 95% confidence interval 1.56,7.39, P = 0.002). Conclusions Persistent physical inactivity in adolescence relates to adult smoking, even after familial factors are taken into account. [source]

Elevated cerebrospinal fluid adiponectin and adipsin levels in patients with multiple sclerosis: a Finnish co-twin study

EUROPEAN JOURNAL OF NEUROLOGY, Issue 2 2010
A. Hietaharju
Background and purpose:, The aim of this study was to investigate the levels of three adipocytokines: leptin, adiponectin and adipsin, in serum and cerebrospinal fluid (CSF) of twins discordant for multiple sclerosis (MS). Adipose tissue is an important component connecting immune system and several tissues and organs including CNS. Fat cells produce adipocytokines, which seem to have a role in various autoimmune disorders including MS. Methods:, Plasma samples were collected from twelve twins and CSF samples from four twins discordant for MS. The concentrations of interleukine (IL)-6, adiponectin, adipsin and leptin in plasma and CSF samples were determined by enzyme immuno assay. Results:, A significant difference was seen in the adipocytokine levels in CSF samples. Twins with MS had higher concentrations of adiponectin (P = 0.039) and adipsin (P = 0.039), than their asymptomatic co-twins. Conclusion:, As adiponectin and adipsin levels in CSF did not correlate with their levels in plasma, it seems that there could be a secondary intrathecal synthesis of these adipocytokines in MS. [source]

Novel Crosslinking of High-order and Multiple Copper Twins in Advanced Microelectronics Packaging,

ADVANCED ENGINEERING MATERIALS, Issue 4 2004
W. Zhang
Novel crosslinking of high-order and multiple copper twins has been formed in the metallization/solder interconnect subjected to the thermal aging. This surprising finding may illustrate a universal metallization failure mode. Meanwhile, many copper nanocrystals in situ originated from those twins crosslinking shed a novel light on the synthesis approach to fascinating nanocrystalline metals. [source]

The effect of sward structure as influenced by ryegrass genotype on bite dimensions and short-term intake rate by dairy cows

GRASS & FORAGE SCIENCE, Issue 1 2003
P. D. Barrett
Abstract The effects of genotypic variation in ryegrasses on sward structure, bite dimensions and intake rate by dairy cows were investigated. Two experiments were conducted. In Experiment 1, swards were in a vegetative state whereas, in Experiment 2, they were partly reproductive and were taller with higher herbage mass but lower leaf proportion than in Experiment 1. Applicability of relationships between sward structure and bite characteristics, previously established from artificial or hand-constructed swards, to field conditions were tested. Additional short-term intake rates and/or sward structural characteristics were considered as indicators of potential intake for use in protocols for the evaluation of grass varieties. Four cultivars were studied: AberElan, Twins (diploid and tetraploid perennial ryegrasses respectively), Polly, a hybrid ryegrass (perennial × Italian ryegrass) and Multimo (Italian ryegrass), each established in 200-m2 plots in four replicated blocks. Herbage intake rate was determined by short-term liveweight change (taking account of insensible weight loss) using 16 dairy cows allocated to four balanced groups with each plot grazed by one group for a 1-h assessment period. One block was grazed per day, over a 4-d experimental period, with each group grazing each variety in a complete crossover design. Sward characteristics and bite rate were also measured in both experiments. Bite dimensions were subsequently estimated, with bite depth being determined as a function of extended tiller height (ETH) in both experiments. Within both experiments, bite mass and intake rate did not differ significantly between swards of different cultivars despite swards containing Multimo generally having a higher ETH and water-soluble carbohydrate concentration and lower green leaf mass, sward bulk density and neutral-detergent fibre concentration than the other swards. However, bite depth was significantly higher (P < 0·01) in swards containing Multimo swards than in the others and, in Experiment 1, bite depth, as a proportion of ETH, was higher in swards containing Multimo and lower in those containing Twins than in the other two cultivars, whereas there was no difference in Experiment 2. Taking both experiments together, the mean bite depth was 0·5 of ETH with sward bulk density accounting for almost half the variance in the relationship between bite depth and ETH. The bulk density of the bite (bite mass per unit bite volume), measured in Experiment 2, followed a similar pattern to sward bulk density, increasing in the order Multimo, Polly, AberElan and Twins. It is concluded that the relationships between sward characteristics and bite dimensions, derived from artificial swards, are applicable to field swards, although the range in natural ryegrass sward characteristics is usually not as wide as in experiments using artificial swards. Lack of precision in the measurement of short-term intake and in sward-based measurements is likely to preclude their use in the evaluation of grass varieties. [source]

Lifetime Prevalence and Characteristics of Recurrent Primary Headaches in a Population-Based Sample of Swedish Twins

HEADACHE, Issue 8 2002
Dan A. Svensson MSc
Objective.,To examine the lifetime prevalence and other characteristics of recurrent primary headaches in twins. Background.,The twin model may provide insights into the role of genetic and environmental influences in headache disorders. However, assumptions as to whether twins are representative of the general population, and whether monozygotic and dizygotic twins are similar have rarely been addressed. Methods.,The study population consisted of a random sample of 17- to 82-year-old twins from the Swedish Twin Registry (n = 1329). Structured interviews on the telephone by lay personnel and the International Headache Society criteria were used for assessment and diagnosis of recurrent primary headaches. Prevalence data of the general population for migraine and tension-type headache was obtained from various published reports. Results.,A total of 372 subjects (29%) had ever had recurrent headaches. In total, 241 recurrent headache sufferers fulfilled the criteria for migraine or tension-type headache, and the lifetime prevalence was 7.1% for migraine without aura, 1.4% for migraine always with aura, 1.9% for migraine occasionally with aura, 9.4% for episodic tension-type headache, and 1.3% for chronic tension-type headache. The lifetime prevalence of all migraine and all tension-type headache, including another 84 subjects fulfilling all but one of the criteria for migraine or tension-type headache, was 13.8% and 13.5%, respectively. The corresponding prevalence risk for women was 2.4 (95% confidence interval [CI] 1.7, 3.4) and 1.5 (95% CI 1.1, 2.1), respectively. Zygosity was not a significant predictor for migraine. In tension-type headache, the prevalence risk for dizygotic twins and unlike-sexed twins as compared with monozygotic twins was 1.9 (95% CI: 1.2, 3.1) and 1.8 (95% CI: 1.1, 2.9), respectively. Conclusion.,There is no twin-singleton or monozygotic-dizygotic difference for the risk of migraine. In tension-type headache, twins seem to have a lower risk than singletons, and this is especially true for monozygotic twins. [source]

Linkage Analysis of Alcohol Dependence Symptoms in the Community

ALCOHOLISM, Issue 1 2010
Narelle K. Hansell
Background:, We have previously identified suggestive linkage for alcohol consumption in a community-based sample of Australian adults. In this companion paper, we explore the strength of genetic linkage signals for alcohol dependence symptoms. Methods:, An alcohol dependence symptom score, based on DSM-IIIR and DSM-IV criteria, was examined. Twins and their nontwin siblings (1,654 males, 2,518 females), aged 21 to 81 years, were interviewed, with 803 individuals interviewed on 2 occasions, approximately 10 years apart. Linkage analyses were conducted on datasets compiled to maximize data collected at either the younger or the older age. In addition, linkage was compared between full samples and truncated samples that excluded the lightest drinkers (approximately 10% of the sample). Results:, Suggestive peaks on chromosome 5p (LODs >2.2) were found in a region previously identified in alcohol linkage studies using clinical populations. Linkage signal strength was found to vary between full and truncated samples and when samples differed only on the collection age for a sample subset. Conclusions:, The results support the finding that large community samples can be informative in the study of alcohol-related traits. [source]

Analysis of Heritability of Hormonal Responses to Alcohol in Twins: Beta-Endorphin as a Potential Biomarker of Genetic Risk for Alcoholism

ALCOHOLISM, Issue 3 2000
J. C. Froehlich
Background: Hormonal responses to alcohol have been reported to differ in subjects with and without a family history of alcoholism which suggests that alcohol-induced hormonal changes might be used to identify individuals who are at elevated genetic risk for developing alcoholism. However, before a biological response can be used as a marker of genetic risk for disease, it must first be demonstrated that the response is, in fact, heritable. The present study was designed to determine whether hormonal responses to alcohol are heritable. Methods: The adrenocorticotropic hormone (ACTH), beta-endorphin (,-E), cortisol (CORT), and prolactin (PRL) responses to alcohol were examined in male and female identical (monozygotic or MZ) and fraternal (dizygotic or DZ) twin pairs. Male subjects consumed 0.35g ethanol/kg body weight (BW) and female consumed 0.325 g ethanol/kg BW in each of two alcohol drinking sessions administered 1 hr apar (total dose of 0.7 g/kg BW in males and 0.65 g/kg BW in females). Plasma hormone content was analyzed in samples collected before (resting conditions) and at 15, 60, 75, 120, 180, and 240 min after onset of drinking. Hormonal responses to alcohol were examined with twin analyses using the TWINAN90 program. A separate analysis was performed for each of the four hormones. A subset of subjects from each zygosity was seen on two separate occasions to establish retest reliability. Heritability of hormonal responses to alcohol was estimated using the intraclass correlation approach before and after removing the contribution of covariates that have the potential of influencing the plasma levels of these hormones. Results: Resting plasma levels of all four hormones were within the expected range, and the ,-E, ACTH, and PRL responses to the alcohol challenge evidenced good test-retest reliability. Of the four hormones examined, the only one that showed significant heritability after alcohol drinking was ,-E. Heritability estimates were not altered for any of the four hormones after removal of the variance contributed by covariates, such as gender and age. Conclusions: Taken together with other recent findings, the results suggest that the ,-E response to alcohol may represent a new biomarker that can be used to identify individuals who are at elevated genetic risk for developing alcoholism. [source]

Necessary Conditions for the Formation of {111} Twins in Barium Titanate

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2000
Byoung-Ki Lee
The experimental conditions for {111} twin formation in BaTiO3 were investigated. When BaTiO3 compacts without excess TiO2 were sintered either in an oxidizing atmosphere (air) or in a reducing atmosphere (95N2,5H2), no {111} twins formed within the BaTiO3 grains and no abnormal grain growth occurred. In contrast, many {111} twins were present within the abnormally grown grains in the excess-TiO2 -containing BaTiO3 samples sintered in air, while no twins were observed in the excess-TiO2 -containing samples sintered in 95N2,5H2. X-ray diffraction analysis showed that excess TiO2 forms a Ba6Ti17O40 phase during sintering with the space group A2/a in air and a Ba6Ti17O40,x phase with the space group C in 95N2,5H2. It appears therefore that excess TiO2 and an oxidizing atmosphere are necessary for {111} twin formation in BaTiO3. These results may also indicate that the interface structure between BaTiO3 and Ba6Ti17O40 influences the twin formation. [source]

Sanctity of life , are some lives more sacred than others?

LEGAL STUDIES, Issue 3 2002
Sabine Michalowski
Court decisions concerning the life and death of patients become more and more frequent in the context of medical practice. One of the most controversial decisions in this area in recent years has been the decision of the Court of Appeal in Re A (Conjoined Twins: Medical Treatment),, authorising the separation of conjoined twins. This paper will argue that the decision was flawed both on legal and moral grounds and that its potential implications for future cases are more far-reaching than the judgment itself suggests. [source]

Studies of twins: what can they tell us about the fetal origins of adult disease?

PAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 2005
Ruth Morley
Summary There has been much interest in evidence that people with lower birthweight have higher risk of adult cardiovascular disease, but the causal pathways underlying such observations are uncertain. Study of twins offers an opportunity to shed light on the underlying causal pathways, in particular by investigating the role of ,shared' factors vs. factors affecting each individual fetus. This involves comparing results of within-cohort vs. within-pair analyses. Twins share many factors during gestation but birthweight discordance (difference in birthweight within a twin pair) cannot be determined by these shared factors and must relate to factors affecting growth of each individual fetus. If associations seen in a cohort of twins remain in within-pair analyses, then factors specific to each individual must be involved in the underlying causal pathways. Conversely, if the relationships disappear or substantially diminish in within-pair analyses, then factors common to the pair must be involved. Comparison of findings in monozygotic vs. dizygotic twins may provide insights into the role of genetic factors, although issues related to chorionicity need to be taken into account. We tabulate published data and conclude that differences in methodology and analyses preclude informative meta-analysis, and that analysis of pooled data would provide more useful information. [source]

Severe Congenital Systemic Juvenile Xanthogranuloma in Monozygotic Twins

PEDIATRIC DERMATOLOGY, Issue 4 2008
Rattanavalai Chantorn M.D.
Juvenile xanthogranuloma with extracutaneous involvement is a rare disease in which significant morbidity and occasional deaths may occur. Monozygotic twins with congenital systemic juvenile xanthogranuloma who presented with multiple skin lesions, hepatosplenomegaly, liver failure, and bone marrow involvement were reported. The diagnosis of systemic juvenile xanthogranuloma was confirmed by histology and immunohistochemical stains of the skin with liver biopsies revealing dense infiltration of lymphohistiocytes with typical Touton giant cells staining positive for CD68 and negative for CD1a and S-100 protein. Both of them received systemic prednisolone 1 mg/kg/day which was gradually tapered off with time according to clinical and investigative responses. At the 17-month follow-up period, both patients showed remarkable regression in all symptoms and laboratory studies. [source]

Congenital Malalignment of the Great Toenails in Dizygotic Twins

PEDIATRIC DERMATOLOGY, Issue 5 2005
Sadiye Kus M.D.
It may cause onychogryphosis and, in infants and children, ingrown nails. We report an occurrence of this deformity in dizygotic twins [source]

Assortative mating by body height and BMI: Finnish Twins and their spouses

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2003
Karri Silventoinen
Assortative mating by body height and weight is well established in various populations, but its causal mechanisms remain poorly understood. We analyzed the effect of phenotypic assortment and social homogamy on spousal correlations for body height and body mass index (BMI, kg/m2). Our data derived from a questionnaire administered to the adult Finnish Twin Cohort in 1990 (response rate 77%) yielding results from 922 monozygotic and 1,697 dizygotic adult twin pairs who reported information about their body height and weight and that of their spouses. Assortative mating was evident for body height and BMI. For body height, the effects of social homogamy (0.24 in men and 0.29 in women) and phenotypic assortment (0.27 and 0.28, respectively) were about the same. For BMI, the effect of social homogamy was stronger (0.31 in men and 0.28 in women) than the effect of phenotypic assortment (0.13 in both men and women). When assortative mating was taken into account, shared environmental factors had no effect on phenotypic variation in body height or BMI. Our results show that assortative mating needs to be considered in population genetic studies of body height and weight. Am. J. Hum. Biol. 15:620,627, 2003. © 2003 Wiley-Liss, Inc. [source]

Food supplementation with an olive (Olea europaea L.) leaf extract reduces blood pressure in borderline hypertensive monozygotic twins

PHYTOTHERAPY RESEARCH, Issue 9 2008
Tania Perrinjaquet-Moccetti
Abstract Hypertension is a harmful disease factor that develops unnoticed over time. The treatment of hypertension is aimed at an early diagnosis followed by adequate lifestyle changes rather than pharmacological treatment. The olive leaf extract EFLA®943, having antihypertensive actions in rats, was tested as a food supplement in an open study including 40 borderline hypertensive monozygotic twins. Twins of each pair were assigned to different groups receiving 500 or 1000 mg/day EFLA®943 for 8 weeks, or advice on a favourable lifestyle. Body weight, heart rate, blood pressure, glucose and lipids were measured fortnightly. Blood pressure changed significantly within pairs, depending on the dose, with mean systolic differences of ,6 mmHg (500 mg vs control) and ,13 mmHg (1000 vs 500 mg), and diastolic differences of ,5 mmHg. After 8 weeks, mean blood pressure remained unchanged from baseline in controls (systolic/diastolic: 133 ± 5/77 ± 6 vs 135 ± 11/80 ± 7 mmHg) and the low-dose group (136 ± 7/77 ± 7 vs 133 ± 10/76 ± 7), but had significantly decreased for the high dose group (137 ± 10/80 ± 10 vs 126 ± 9/76 ± 6). Cholesterol levels decreased for all treatments with significant dose-dependent within-pair differences for LDL-cholesterol. None of the other parameters showed significant changes or consistent trends. Concluding, the study confirmed the antihypertensive and cholesterol-lowering action of EFLA®943 in humans. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Clinical significance of chimerism,

AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 2 2009
Dianne Abuelo
Abstract Twins have been previously classified as either monozygotic or dizygotic. In recent years, fascinating, non-traditional mechanisms of twinning have been uncovered. We define chimerism versus mosaicism, touch on chimerism in the animal world, and explain timing of chimerism in humans. In addition, we discuss when to suspect chimerism in patients, and how to proceed with diagnostic evaluation and confirmation. © 2009 Wiley-Liss, Inc. [source]

Health care supervision for twin pairs,

AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 2 2009
Joy Samanich
Abstract Twins are at increased risk for congenital anomalies and have particular health care needs, but twin management guidelines do not exist. This review attempts to integrate the latest research findings and evidence-based medicine on twins into basic clinical recommendations for general pediatricians. © 2009 Wiley-Liss, Inc. [source]

Economic Returns to Communist Party Membership: Evidence From Urban Chinese Twins,

THE ECONOMIC JOURNAL, Issue 523 2007
Hongbin Li
This article estimates the returns to membership of the Chinese Communist Party using unique twins data we collected from China. Our OLS estimate shows a Party premium of 10%, but the within-twin-pair estimate becomes zero. One interpretation is that the OLS premium is due to omitted ability and family background. This interpretation suggests that Party members fare well not because of their political status but because of the superior ability that made them Party members. The estimates are also consistent with another interpretation that Party membership not only has its own effect but also has an external effect on siblings. [source]

Genetic and environmental influences on the transmission of parental depression to children's depression and conduct disturbance: an extended Children of Twins study

THE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 6 2010
Judy L. Silberg
Background:, Despite the increased risk of depression and conduct problems in children of depressed parents, the mechanism by which parental depression affects their children's behavioral and emotional functioning is not well understood. The present study was undertaken to determine whether parental depression represents a genuine environmental risk factor in children's psychopathology, or whether children's depression/conduct can be explained as a secondary consequence of the genetic liability transmitted from parents to their offspring. Methods:, Children of Twins (COT) data collected on 2,674 adult female and male twins, their spouses, and 2,940 of their children were used to address whether genetic and/or family environmental factors best account for the association between depression in parents and depression and conduct problems in their children. Data collected on juvenile twins from the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) were also included to estimate child-specific genetic and environmental influences apart from those effects arising from the transmission of the parental depression itself. The fit of alternative Children of Twin models were evaluated using the statistical program Mx. Results:, The most compelling model for the association between parental and juvenile depression was a model of direct environmental risk. Both family environmental and genetic factors accounted for the association between parental depression and child conduct disturbance. Conclusions:, These findings illustrate how a genetically mediated behavior such as parental depression can have both an environmental and genetic impact on children's behavior. We find developmentally specific genetic factors underlying risk to juvenile and adult depression. A shared genetic liability influences both parental depression and juvenile conduct disturbance, implicating child conduct disturbance (CD) as an early indicator of genetic risk for depression in adulthood. In summary, our analyses demonstrate differences in the impact of parental depression on different forms of child psychopathology, and at various stages of development. [source]

Ethics: English High Court Orders Separation of Conjoined Twins

THE JOURNAL OF LAW, MEDICINE & ETHICS, Issue 3 2000
Jacob M. Appel
First page of article [source]

SHORT COMMUNICATION: History of Incidence of Autoimmune and Oncological Diseases in Identical Female Twins

Twinning and intergrowth of rare earth boride carbides

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2002
Oliver Oeckler
Twins and intergrown crystals of tetragonal rare earth boride carbides, especially those with the La5B2C6 structure type, have been investigated by high-resolution electron microscopy and X-ray diffraction. The structure of the twin interface has been determined. It provides an explanation for coherently intergrown domains of different structure. The Sc3C4 structure type is remarkable because it is frequently intergrown with La5B2C6 -type phases. It provides, for instance, a model for the intergrowth of other types, e.g. Gd4B3C4 and Gd5B2C5. The presence of metal-atom square nets in different orientations in the structures accounts for a number of intergrowth phenomena. The possibilities and limitations of X-ray structure determinations are discussed with respect to actual examples. [source]