Perinuclear antineutrophil cytoplasmic antibodies (P-ANCA) have been demonstrated in patients with ulcerative colitis and in a higher frequency than expected in their first degree relatives. A hypothesis was proposed that P-ANCA is genetically determined and may represent a subclinical marker of genetic susceptibility to ulcerative colitis. This study analysed P-ANCA in monozygotic twins with inflammatory bowel disease to evaluate this hypothesis further. P-ANCA was analysed with indirect immunofluorescence technique in 12 monozygotic twin pairs with ulcerative colitis and 14 twin pairs with Crohns disease. Furthermore, the study included 21 non-twin patients with ulcerative colitis, 18 non-twin patients with Crohns disease, and 52 healthy controls matched for sex and age. In ulcerative colitis P-ANCA occurred in nine of 14 (64.3%) monozygotic twins and in 13 of 21 (61.9%) non-twin cases, which was significantly different compared with healthy controls who were positive in three of 52 (5.8%) ...
Monozygotic twins are genetically nearly identical and they are always the same sex unless there has been a mutation during development. The children of monozygotic twins test genetically as half-siblings (or full siblings, if a pair of monozygotic twins reproduces with another pair or with the same person), rather than first cousins. Identical twins do not have the same fingerprints however, because even within the confines of the womb, the fetuses touch different parts of their environment, giving rise to small variations in their corresponding prints and thus making them unique.[28]. Monozygotic twins always have the same phenotype. Normally due to an environmental factor or the deactivation of different X chromosomes in female monozygotic twins, and in some extremely rare cases, due to aneuploidy, twins may express different sexual phenotypes, normally from an XXY Klinefelter syndrome zygote splitting unevenly.[29][30][31]. Monozygotic twins, although genetically very similar, are not ...
The role of heredity in the presence of asthma, severity of the condition, and impact of 12 specific triggers of attacks was investigated. Health surveys containing questions about childrens asthma characteristics were completed by 325 families with twin children across the United States. Data for 39 monozygotic twin pairs and 55 same sex dizygotic twin pairs who were between 2 and 20 years of age and had asthma present in at least one member of each pair were received and analysed. Results revealed higher concordance for the presence of asthma among monozygotic (58.97%; n = 23) than dizygotic twins (23.64%; n = 13). Further analyses were restricted to data from the concordant monozygotic and dizygotic twin pairs. Asthma severity (the product of attack frequency and intensity ratings) was significantly correlated for monozygotic pairs but not for dizygotic pairs, and this difference in monozygotic and dizygotic severity correlations was significant. Also, monozygotic twins showed significantly ...
Although clones start off identical, they may not stay that way. Identical twins always have slightly different phenotypes.[2][3]. Although monozygotic twins are genetically almost identical, a 2012 study of 92 pairs of monozygotic twins found that monozygotic twins acquire several hundred genetic differences early in foetal development. This is caused by mutations (or copy errors) taking place in the DNA of each twin after the splitting of the embryo.[4] It is estimated that, on average, a set of monozygotic twins will have about 360 genetic differences that occurred early in foetal development. However, these changes may have little practical effect. In practice, identical twins look and act in a very similar way. Another cause of difference between monozygotic twins is epigenetic modification. These are caused by differing environmental influences throughout their lives, which affects which genes are switched on or off. A study of 80 pairs of monozygotic twins ranging in age from three to 74 ...
Although clones start off identical, they may not stay that way. Identical twins always have slightly different phenotypes.[2][3] Although monozygotic twins are genetically almost identical, a 2012 study of 92 pairs of monozygotic twins found that monozygotic twins acquire several hundred genetic differences early in foetal development. This is caused by mutations (or copy errors) taking place in the DNA of each twin after the splitting of the embryo.[4] It is estimated that, on average, a set of monozygotic twins will have about 360 genetic differences that occurred early in foetal development. However, these changes may have little practical effect. In practice, identical twins look and act in a very similar way. Another cause of difference between monozygotic twins is epigenetic modification. These are caused by differing environmental influences throughout their lives, which affects which genes are switched on or off. A study of 80 pairs of monozygotic twins ranging in age from three to 74 ...
Multiple genetic and environmental factors interact to determine an individuals predisposition to non-alcoholic fatty liver disease and its phenotypic characteristics. Association studies have found a number of alleles associated with the development of non-alcoholic steatohepatitis. Our aim was to investigate whether multiple risk-associated alleles may be present in affected monozygotic twins, indicating underlying genetic predisposition to non-alcoholic steatohepatitis. We determined the genotype of 14 candidate gene polymorphisms (at 11 unlinked loci) in a set of monozygotic twins with who presented with cirrhosis within 18 months of each other. Genotyping revealed multiple single nucleotide polymorphisms at 9 independent loci in genes PNPLA3, APOC3, GCKR, TRIB1, LYPLAL1, PPP1R3B, COL13A1, and EFCAB4B, previously implicated in contributing to non-alcoholic steatohepatitis pathogenesis. In conclusion, this case series illustrates the potential cumulative effect of multiple polymorphisms in ...
Global DNA Methylation Is Associated With Insulin Resistance A Monozygotic Twin Study. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
TY - JOUR. T1 - Epigenetic variation in monozygotic twins. T2 - A genome-wide analysis of DNA methylation in buccal cells. AU - van Dongen, Jenny. AU - Ehli, Erik A.. AU - Slieker, Roderick C.. AU - Bartels, Meike. AU - Weber, Zachary M.. AU - Davies, Gareth E.. AU - Slagboom, P. Eline. AU - Heijmans, Bastiaan T.. AU - Boomsma, Dorret I.. PY - 2014/1/1. Y1 - 2014/1/1. N2 - DNA methylation is one of the most extensively studied epigenetic marks in humans. Yet, it is largely unknown what causes variation in DNA methylation between individuals. The comparison of DNA methylation profiles of monozygotic (MZ) twins offers a unique experimental design to examine the extent to which such variation is related to individual-specific environmental influences and stochastic events or to familial factors (DNA sequence and shared environment). We measured genome-wide DNA methylation in buccal samples from ten MZ pairs (age 8-19) using the Illumina 450k array and examined twin correlations for methylation ...
Nordström et al report of 4046 monozygotic twins with discordant body mass indexes identified from a Swedish twin registry. The study recruitment was between 1998 and 2003 and follow up to December 2013. The primary end-point was the composite of death and myocardial infarction. The abstract follows: IMPORTANCE Observational studies have shown that obesity is…
Following widespread application of assisted reproductive technology modalities and the increased age of motherhood, the incidence of twin gestations has increased markedly. Twins are either monozygotic or dizygotic. Dizygotic (i.e. fraternal) twins result from the fertilization of two different eggs and are per definition dichorionic (DC). Chorionicity of monozygotic twins ... read more (i.e. identical twins) depends on timing of splitting of the fertilized egg. If splitting occurs within three days after fertilization, the monozygotic twin will be DC. Splitting after the third day results in monochorionic (MC) twinning. Twins have an increased risk of perinatal mortality and neonatal morbidity compared to singletons. MC twin pregnancies, which occur in about 1 of 400 pregnancies, carry a higher risk of perinatal complications compared to DC twins. This is mainly attributed to the unique architecture of the MC placenta. The aim of this thesis was to study perinatal mortality and (long-term) ...
This is a fascinating study of identical twins; one had gender dysphoria and one did not. Both twins developed anorexia. Both twins were feminine in behavior from a young age and both were sexually attracted to men. Both had a difficult childhood with an abusive father. Both twins were underweight at birth and needed intensive care. Both…
A method of estimating the probability of dizygotic and monozygotic twin pairs is described. Parent-child and sib-sib frequency tables for the ABO, MNS and Rhesus blood-group systems and formulae for obtaining these tables for the P, Lutheran, Kell, Duffy, Kidd and non-secretor (or Lewis) systems are given.. Tables of the distribution of differences in total finger ridge count and atd palmar angles are also given.. The probability that a given twin pair is monozygotic is estimated in two worked examples. ...
Results We conservatively characterised 23 de novo SNVs shared by the twin pair, 8 de novo SNVs specific to twin I and 1 de novo SNV specific to twin II. Based on the number of de novo SNVs validated by Sanger sequencing and the number of callable bases of each twin, we calculated the overall de novo SNV rate of 1.31×10−8 and 1.01×10−8 for twin I and twin II, respectively. Of these, rates of the early postzygotic de novo SNVs were estimated to be 0.34×10−8 for twin I and 0.04×10−8 for twin II.. ...
This study will evaluate the safety of giving lymphocytes (white blood cells) containing a new gene to HIV-infected individuals and will determine how long the cells survive in the bloodstream. Although the genetically altered cells will not directly benefit participants, knowledge about the safety, side effects and survival of these gene-marked cells in HIV-infected patients may lead to new treatment strategies.. Identical twin pairs 18 years of age and older-one infected with HIV, the other non-infected-may be eligible for this study. Candidates will be screened with a medical history, physical examination and blood tests.. All participants will have a tetanus booster shot. Non-infected twins will undergo a procedure called apheresis to collect white blood cells. For this procedure, whole blood is collected through a needle in an arm vein, similar to donating blood. The blood is separated it into its components by centrifugation (spinning), the white cells are removed, and the rest of the ...
Since RNA viruses have been shown to cause leukemia in mice, rats, cats, and birds, intensive studies have attempted to link similar viruses with human leukemia. In the absence of a demonstrable human leukemia virus, immunological attempts to detect viral antigens have been hampered by lack of suitable controls. This study of identical twins, one with leukemia and one clinically normal, provided an excellent opportunity to use a variety of test procedures to detect an antigen in the leukemic patient, possibly tumor-specific, that would not be present in the identical twin. Four sets of identical twins, all children with acute ...
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Did you ever wish you had access to a searchable database of twin correlations and trait heritability statistics? If not, once you see this, you will wonder why you hadnt been looking for this kind of resource. Shout out to David Myers (Hope College) for pointing me toward MaTCH. Lets take height as an example. From the first drop-down menu, select "ICF/ICD10 Subch" and then from the second drop-down menu, select "Height (297). The number in parentheses refers to the number of studies included in the displayed data. This is the first chart that is generated. If one identical (mz = monozygotic) twin is tall, there is a very good chance the other will be as well. If one is short, there is a very good chance the other will be as well. The correlation between being a twin and height is .91. The chart also gives correlations for just male identical twins (mzm = monozygotic male) and female identical twins (mzf = monozygotic female). If one fraternal (dz = dizygotic) twin is tall, there is a smaller ...
TY - JOUR. T1 - DNA methylation profiles in type 1 diabetes twins point to strong epigenetic effects on etiology. AU - Stefan, Mihaela. AU - Zhang, Weijia. AU - Concepcion, Erlinda. AU - Yi, Zhengzi. AU - Tomer, Yaron. PY - 2014/5. Y1 - 2014/5. N2 - Type 1 diabetes (T1D) shows ~40% concordance rate in monozygotic twins (MZ) suggesting a role for environmental factors and/or epigenetic modifications in the etiology of the disease. The aim of our study was to dissect the contribution of epigenetic factors, particularly, DNA methylation (DNAm), to the incomplete penetrance of T1D. We performed DNAm profiling in lymphocyte cell lines from 3 monozygotic (MZ) twin pairs discordant for T1D and 6 MZ twin pairs concordant for the disease using HumanMethylation27 BeadChip. This assay assesses the methylation state of 27,578 CpG sites, mostly located within proximal promoter regions. We identified 88 CpG sites displaying significant methylation changes in all T1D-discordant MZ twin pairs. Functional ...
Schizophrenia is a debilitating mental illness which is complex and multifactorial in nature. Currently a full understanding of the exact aetiological and treatment pathways is yet to be understood, with effective treatment of the debilitating and pervasive negative symptoms particularly lacking. However recent advances in neurophysiological and neuropsychological research seem to be converging on theories of the central role of lateralised functional systems. These models implicate right hemispheric hyperactivation in negative symptom patterns, while positive symptoms are thought to be associated with left frontal hypoactivation resulting in compensatory left temporal hyperactivation. Through the use of the Cognitive Neuropsychological case study methodology, this research took an inductive and exploratory approach to a unique case of 41 year old monozygotic twins concordant for schizophrenia and discordant for a right frontal cerebrovascular accident (CVA). From various records the CVA ...
TY - JOUR. T1 - Analysis of genetic and nongenetic factors influencing triglycerides-lowering drug effects based on paired observations. AU - Xu, Zheng. AU - Duan, Qing. AU - Cui, Juan. AU - Qiu, Yumou. AU - Jia, Qidong. AU - Wu, Cong. AU - Clarke, Jennifer L. PY - 2018/9/17. Y1 - 2018/9/17. N2 - Obesity is a risk factor for heart disease, stroke, diabetes, high blood pressure, and other chronic diseases. Some drugs, including fenofibrate, are used to treat obesity or excessive weight by lowering the level of specific triglycerides. However, different groups have different drug sensitivities and, consequently, there are differences in drug effects. In this study, we assessed both genetic and nongenetic factors that influence drug responses and stratified patients into groups based on differential drug effect and sensitivity. Our methodology of investigating genetic factors and nongenetic factors is applicable to studying differential effects of other drugs, such as statins, and provides an ...
Multifetal gestations are classified on the basis of zygosity and chorionicity.1Dizygotic twins arise from independent fertilization of separate ova. Typically, two placentas form with distinct chorionic and amniotic membranes separating each fetus. Monozygotic twins develop from a single fertilized ovum that subsequently divides at or before the blastocyst stage of embryogenesis. The factors promoting fission of the conceptus are poorly understood. The timing of embryonic division determines whether the monozygotic twins will be separated by amnion and chorion (dichorionic, diamniotic), amnion only (monochorionic, diamniotic), or not separated (monoamniotic, monochorionic). Dizygotic twins account for about two thirds of spontaneous twin births and are almost always dichorionic, diamniotic. Monochorionic twins share a single placenta with a shared circulation. This developmental phenomenon carries a significant mortality risk and may lead to complications such as twin-twin transfusion syndrome ...
Postmenopausal bone mass is determined by both peak bone mass and subsequent bone loss. Previous studies have shown that peak bone mass is under genetic influence mediated partly by factors affecting bone formation. The rate of bone loss increases markedly after the menopause, but is highly variable from subject to subject. The aims of this study were to determine whether postmenopausal bone turnover was under genetic control, which should be linked to the genetic influence on the rate of postmenopausal bone loss. A classical twin study was performed that compared the intraclass correlations in monozygotic (MZ) twins with those in dizygotic (DZ) twins, with any difference assumed to be due to genetic factors. Markers of bone formation and resorption were measured in 240 untreated postmenopausal twins, aged 45-69 yr, on the average 12.3 yr (SD, 6.0) postmenopause, including 61 MZ pairs and 59 DZ pairs. The intraclass correlation coefficient of MZ twin pairs, rMZ (95% confidence interval), for 2 specific
The sometimes-preternatural similarity of identical twins is more profound than previously thought. Identical twins, known to science as "monozygotic", may share more than identical looks and genes, according to new research in the field of epigenetics … ...
How cool is that? The #Rangers have drafted identical twins in this years #MLBDraft! Heres David & Ryan Ledbetter! twitter.com/Alleycat17/sta… - April Whitzman (@Alleycat17) June 13, 2013I grew up with a set of identical twins in some of my classes. I noticed that in many cases they not only shared physical features but similar likes, skills and traits. This is certainly true for David and Ryan Ledbetter, twin brothers who were each selected in the 2013 MLB Draft. What makes this even more special? They were both drafted by the same team - the Texas Rangers.The brothers are both right-handed pitchers, though David profiles as a stronger pitcher due to his outstanding control and incredible change-up. David was drafted 99th overall, while his brother was the 580th player called.It is these stories that make the MLB Draft even that much more interesting to follow. The only thing that could have topped this is had they been drafted for the Minnesota … (wait for it) … Twins!
Methods and Results-Seventy-eight monozygotic twin pairs (aged 42.4±16.8 years) and 24 same-sex dizygotic twin pairs (aged 50.5±16.1 years) were examined. Anteroposterior and mediolateral diameters of the common femoral vein were measured by ultrasonography. Measurements were made both in supine and in standing body positions, with or without controlled forced expiration (Valsalva test). High correlation of diameter, capacity, and distensibility values was found between twin pairs. The univariate heritability (A), shared (C), and unshared (E) environmental effects model has shown 39.3% genetic component of the variance of low pressure, 37.9% of high-pressure venous capacity, and 36.4% of maximal capacity changes, even after elimination of sex, age, and body weight effects. Bivariate Cholesky analysis revealed substantial covariance of inherited body weight and venous capacity components (57.0%-81.4%).. ...
An innovative feature of the current study is the use of twins to test the prenatal programming hypothesis. Twins share the same maternal environment, and monozygotic twins are genetically identical. Nevertheless, each fetus has its own fetoplacental environment, as reflected by its birth weight, that may differ substantially between twin members. By comparing the BP of the heaviest twin at birth with that of the lighter sibling, potential confounding maternal and genetic characteristics can be controlled. So far, only 4 studies have applied this twin approach for BP,4-7 but their results have not been consistent. Dwyer et al4 and Poulter et al5 found a tendency for the monozygotic twin who was lightest at birth to have the highest BP later in life, suggesting that the association between birth weight and adult BP is at least partly independent from maternal and genetic influences. Ijzerman et al6 observed an inverse relationship between intrapair birth weight difference and intrapair difference ...
SAN CARLOS, Calif., Oct. 2, 2017 /PRNewswire/ - Natera (NASDAQ: NTRA), a leader in non-invasive genetic testing and the analysis of circulating cell-free DNA, today announced that the companys Panorama® non-invasive prenatal test (NIPT) is now validated to screen twin pregnancies for zygosity (identical or non-identical/fraternal) and chromosomal abnormalities.. Nateras Panorama® is the first NIPT that can determine whether twins are monozygotic (identical) or dizygotic (non-identical or fraternal) as early as nine weeks gestation.1 Accurately assessing zygosity early in twin pregnancies is important; Panorama identified monozygotic twins with ,99% sensitivity and specifi-city in validation studies.1 Monozygotic pregnancies can be at risk for complications that come from monochorionicity (a shared placenta). About 67% of monozygotic pregnancies are monochorionic pregnancies, which are at the highest risk for intrauterine growth restriction, birth defects, and twin-twin transfusion syndrome ...
Multiple sclerosis (MS) is a disabling disease of the CNS. Inflammatory features of MS include lymphocyte accumulations in the CNS and cerebrospinal fluid (CSF). The preclinical events leading to established MS are still enigmatic. Here we compared gene expression patterns of CSF cells from MS-discordant monozygotic twin pairs. Six "healthy" co-twins, who carry a maximal familial risk for developing MS, showed subclinical neuroinflammation (SCNI) with small MRI lesions. Four of these subjects had oligoclonal bands (OCBs). By single-cell RNA sequencing of 2752 CSF cells, we identified clonally expanded CD8+ T cells, plasmablasts, and, to a lesser extent, CD4+ T cells not only from MS patients but also from subjects with SCNI. In contrast to nonexpanded T cells, clonally expanded T cells showed characteristics of activated tissue-resident memory T (TRM) cells. The TRM-like phenotype was detectable already in cells from SCNI subjects but more pronounced in cells from patients with definite MS. ...
Because the defect in IL-4 secretion was likely the result of multiple differences, a representative clone pair was chosen for intensive analysis with DNA microarrays that monitor the expression of ≈6,800 genes (Unigene collection; National Center for Biotechnology Information, Bethesda, MD). The DNA microarrays provide a practical and reproducible approach for large-scale study of complex differences in gene expression (11-14). Expression profiles were determined after 4 h of stimulation with anti-CD3 or control IgG. This time point was selected because it was used in a previous analysis of cytokine secretion in clones derived from monozygotic twin pairs discordant for type 1 diabetes (8). The number of genes with detectable expression either before or after stimulation was nearly identical for the IL-4 null and IL-4-secreting clones (1,523 and 1,558, respectively). As expected, the frequency of the majority of transcripts was unchanged. Interestingly, only about 2/3 of this set (988) were ...
As part of the BLUEPRINT Consortium, we aim to identify variation in DNA methylation associated with type 1 diabetes mellitus (T1DM). We have collected immune effector and control cell types from monozygotic twins discordant for T1DM, including CD4+ lymphocytes, CD14+CD16- monocytes, CD19+ B cells and buccal cells. In addition, we have collected Guthrie card samples from progressors and non-progressors to T1DM, and peripheral lymph node and spleen samples of both T1DM cases and healthy controls. Our initial aim is to pre-screen the monozygotic twin pairs discordant for T1DM using the Illumina 450K array platform and whole-genome bisulphite sequencing in selected immune effector cells. Overall, we aim to generate DNA methylation profiles in a total of 1,000 samples. The analysis will include validation of the T1DM methylation signature using a targeted bisulphite sequencing platform, such as RainDrop BS-seq (see: Methylome Analysis), integration with GWAS data, biological pathway analysis and ...
TY - JOUR. T1 - Congenital deuteranomaly in one of monozygotic female triplets. AU - Yokota, A.. AU - Shin, Y.. AU - Seki, R.. AU - Tsubota, Kazuo. PY - 1989. Y1 - 1989. UR - http://www.scopus.com/inward/record.url?scp=0024848223&partnerID=8YFLogxK. UR - http://www.scopus.com/inward/citedby.url?scp=0024848223&partnerID=8YFLogxK. M3 - Article. AN - SCOPUS:0024848223. VL - 43. SP - 1911. EP - 1915. JO - Japanese Journal of Clinical Ophthalmology. JF - Japanese Journal of Clinical Ophthalmology. SN - 0370-5579. IS - 13. ER - ...
Monozygotic or identical twins are the only people in the world who have the same genotype. Twins embryos are formed from a single zygote that is divided i...
Monozygotic twinning is rare within populations yet taxonomically widespread. We explore the evolution of monozygotic twinning by modeling an allele in a newly formed offspring that causes it to undergo mitosis and separation to form one or more clones (twins), potentially in conflict with the parents best interest. The success of this twinning allele in our haploid models depends on the balance of the benefit of increased frequency in the clutch and the cost of reduced survival resulting from limited parental resources. The trait reaches high frequency in a broad range of plausible conditions but also fails to spread or is kept at low frequency in others when the survival cost is high (e.g., in small clutch sizes). Interestingly, there are two reasonable conditions that predict high frequency of the trait but low visibility: random parental abortion and selection for low penetrance. Thus our models suggest reasons why monozygotic twinning might be rare, or alternatively, be common yet appear ...
Published April 23, 2013 in Molecular Psychiatry This study suggests environmentally driven changes to the epigenome may contribute to the development of ASD and ASD-related behaviors. The study, which involved identical twins who were discordant for ASD and related traits, is the first large-scale examination of the role of genome-wide DNA methylation in ASD.. http://www.nature.com/mp/journal/vaop/ncurrent/full/mp201341a.html. Filed under: Autism Research, Autism Science, Copy Number Variations, Epigenetics, featured, Genetics, Genomics. ...
This study of 571 monozygous and 380 dizygous female twin pairs has shown that the mammographic areas of dense tissue and nondense tissue both have high heritability of about 65%; the same as has been previously reported for PMD. These findings pertained to both age-adjusted, and age- and covariate-adjusted mammographic measures. The two mammographic measures were negatively correlated within the same individual. The magnitude of the negative correlation between the two measures across twin pairs was greater in monozygous than dizygous pairs, suggesting that genetic factors explain two thirds of the within-individual correlation. These findings were consistent and similar whether using the Australian or North American samples.. The findings above have been derived under the assumptions of the classic twin model, which attributes greater correlations in monozygous pairs than dizygous pairs solely to genetic factors. This model makes the critical assumption that the strength of nongenetic factors ...
X inactivation makes females mosaics for 2 cell populations, usually with an approximate 1:1 distribution. Skewing of this distribution in peripheral blood cells is more common among elderly women.(1-3) The depletion of hematopoietic stem cells followed by random differentiation may explain the acquired skewing with age.(4) However, an animal model suggests that selection processes based on X-linked genetic factors are involved.(5) We studied peripheral blood cells from 71 monozygotic twin pairs aged 73 to 93 years and from 33 centenarians, and we found that with age, 1 of the cell populations becomes predominant for most women. We also observed a strong tendency for the same cell line to become predominant in 2 co-twins. This suggests that X-linked genetic factors influence human hematopoietic stem cell kinetics. The fact that females have 2 cell lines with different potentials could be one of the reasons women live longer than men. (© 2000 THE AMERICAN SOCIETY CT HEMATOLOGY). ...
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Green senior football standouts Zach Wieland and Seth Wieland are identical twin brothers, yet they have different birthdays after being born 30 minutes apart. Zach was born at 11:59 p.m. July 26, 1994, and Seth was born at 12:29 a.m. on July 27, 1994.
A twin study like this one involves analyzing data on identical twins. (Twin pairs that are not identical, and therefore do not have identical DNA, provide much less information about genetic effects). The study can give a statistical figure for the percentage of risk for some condition (Alzheimers disease in this case) that is attributable to genetics. In this case, the risk is 79% (with 95% confidence). The implication is that in only about one fifth of identical twin pairs the disease will develop in one of the twins but not the other, presumably on account of some sort of environmental influence. In fact, in only about 45% of pairs where one twin has developed the disease has it appeared in the other also -- though it may well appear if the other twin lives long enough ...
TWIN studies have been broadly used as a tool to investigate heritability for decades. A recent comprehensive meta-analysis reported 17,804 heritability estimates for various traits based on twin studies (Polderman et al. 2015). Estimation methods and software such as structural equation modeling (SEM) based on the classical twin models consisting of additive genetic, common, and unshared environmental effects have been well established and extensively adopted (Rijsdijk and Sham 2002). Extensions for longitudinal data or time-to-event phenotypes based on the classical twin models have been proposed (Boomsma et al. 1989; Pitkäniemi et al. 2007). Nevertheless, one of the major issues posing potential challenge is that many twin data sets contain individuals across a wide range of age and the variances of genetic and environmental components for many complex traits such as body mass index (BMI) and height change over age (Lajunen et al. 2009; Elks et al. 2012) or birth cohorts (Silventoinen et al. ...
Downloadable! Why do well-educated people live longer? We use unique and high-quality data on about 50,000 monozygotic and same-sex dizygotic twins, born between 1886-1958, to address this question. We demonstrate a positive and statistically signiÂ…cant relation between years of schooling and longevity, which remains when we exploit the twin design. This result is robust to controlling for speciÂ…c within-twin-pair differences in early life factors, such as birth weight and proxies for ability and health in the form of body height, as well as to restricting the sample to monozygotic twins.
Genes vs. Environment. Some of the most startling and convincing data on the relative influences of genes vs. environment come from studies of identical twins who were separated at birth and reared apart. Identical twins come from a single egg that splits in two; the twins are genetically identical. Fraternal twins are produced by a double ovulation and are no more genetically alike than ordinary siblings. (Unlike fraternal twinning rates, there are no racial differences in the frequencies of identical twinning.). The crucial finding is that identical twins reared apart are more like each other in virtually every way than are fraternal twins who were reared in the same household. From these similarities it is possible to estimate how much of the variation in personality traits is caused by genes and how much by environment.. The chart at the bottom of this page shows twin-study estimates of the genetic contribution to various attitudes. These estimates almost certainly undervalue heritability ...
Julie de Waroquiers photo series entitled Chimeras features sets of identical twins side-by-side in ethereal settings. The photographer from Lyon tracked down subjects through social media and word-of-mouth. She also attended the annual twins festival in the town of Pleucadeuc in Brittany.
Twin studies[2] provide a way to understand how genotype affects an observable characteristic (called a phenotype). In short, identical (monozygotic) twins carry the same alleles for 100% of their genes whereas fraternal (dizygotic) twins will carry different alleles at 50% of the genes for which their parents had different genotypes. So if some characteristic (say, depression) that is observed in one identical twin is always observed in the other one, but this does not hold for fraternal twins, then one can conclude that heredity plays an important role in causing the condition. Boomsma has been a pioneer in collecting a broad spectrum of data (e.g., medical histories, IQ tests, MRI scans) and biological material (e.g., DNA and RNA samples, blood and urine samples) from thousands of twins and analyzing them to determine the role of genetics in characteristics as varied as adult height, brain volume, intelligence, migraine headaches, anxiety, drug addiction, and love of coffee. Her results span ...
Dr. Phil met 16-year-old identical twins Taylor and Tricia in 2016 when they each weighed less than 80 lbs. The sisters were referred to separate treatment facilities to address their eating disorders, and as of September 2019, report having gained over 4
Reviews and evaluates psychological studies of separately raised identical twins and suggests which aspects of human experience are largely shaped by ones heredity
New mother Holli Gorveatt, of Kirkland, Wash., is pre- and post-partum with her identical twins after giving birth to one last month and expecting her next to arrive in January.
Seven pairs of young adult male identical twins completed a negative energy balance protocol during which they exercised on cycle ergometers twice a day, 9 out of 10 days, over a period of 93 days while being kept on a constant daily energy and nutrient intake. The total energy deficit caused by exe …
Data for each trait were z-transformed and winsorized such that the extreme 0.3% of values in this study (i.e., those exceeding ±3 SDs from the mean) were replaced with ±3. Winsorization is a common statistical technique for dealing with data outliers, such that distributional tail values are constrained to some prespecified percentile. Data were then subset into eight groups based on zygosity and sex: monozygotic females (MZF), monozygotic males (MZM), dizygotic females (DZF), dizygotic males (DZM), dizygotic opposite sex pairs with females first-born (DZFM) and males first-born (DZMF), female siblings (Sib F) and male siblings (Sib M). Software (OpenMx) 19 was used to test the assumption that the means and variances for each trait did not differ between individuals within and across groups. In the first instance a saturated (control) model was fitted to the raw data and all parameters freely estimated. Twelve univariate, nested models were subsequently fitted in a stepwise fashion, with each ...
An international group of researchers has discovered a new phenomenon that occurs in identical twins: independent of their identical genes, they share an additional level of molecular similarity that influences their biological characteristics. The researchers propose a mechanism to explain the extra level of similarity and show that it is associated with risk of cancer in adulthood. The results appear in the journal Genome Biology.