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Monozygotic Twins (monozygotic + twin)

Distribution by Scientific Domains
Medical Sciences54%
Life Sciences40%
2 Other Domains6%

Terms modified by Monozygotic Twins

  • monozygotic twin discordant
    		•

    Selected Abstracts

    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]

    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]

    Monozygotic twins are discordant for chronic periodontitis: clinical and bacteriological findings

    JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2010
    Gaudy L. Torres de Heens
    Torres de Heens GL, Loos BG, van der Velden U. Monozygotic twins are discordant for chronic periodontitis: clinical and bacteriological findings. J Clin Periodontol 2010; 37: 120,128. doi: 10.1111/j.1600-051X.2009.01511.x. Abstract Objectives: The aim of this study was to assess, in monozygotic (MZ) and dizygotic (DZ) twin pairs in whom the proband of the twin pair was suffering from moderate to severe chronic periodontitis, the contribution of genetics, periodontal pathogens and lifestyle factors towards the clinical phenotype. Material and Methods: For this study, 18 adult twin pairs were selected on the basis of interproximal attachment loss (AL) 5 mm in 2 non-adjacent teeth in one twin member. The study included 10 MZ and eight DZ twin pairs, in whom the periodontal condition, presence of periodontal pathogens, educational level, smoking behaviour and body mass index (BMI) were evaluated. Results: Both MZ and DZ twins were discordant regarding AL and alveolar bone loss. Discordance was greater in DZ compared with MZ twins. In MZ twins, the discordance could not be explained by education, smoking, BMI and periodontal pathogens. In DZ twins, 45.6% of the discordance could be explained by more pack-years of the probands. Conclusion: The results confirm a possible role of genetic factors in periodontitis. However, the magnitude of the genetic effects on disease severity may have been overestimated previously. [source]

    Factors influencing twins and zygosity

    PAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 2005
    Gary V. D. Hankins
    Summary Zygosity is influenced by many factors. Monozygotic twins occur spontaneously in approximately 1 in 250 births and are felt to increase twofold with ovulation induction techniques. Monozygotic twinning also increases in proportion to the number of blastocysts transferred during in vitro fertilisation. In contrast, dizygotic twinning appears to be influenced by race, genetic factors, maternal age, fertility enhancing drugs, folic acid supplementation, and maternal nutritional status. [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]

    Non-identical monozygotic twins, intermediate twin types, zygosity testing, and the non-random nature of monozygotic twinning: A review,

    AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 2 2009
    Geoffrey Machin
    Abstract Monozygotic twins (MZ) are rarely absolutely "identical." This review discusses the types of genetic/epigenetic and prenatal environmental post-zygotic mechanisms that cause discordance within such twin pairs. Some of these mechanisms,ranging from heterokaryotypia to skewed X-chromosome inactivation,may cause extreme discordance, but these extremes are merely the more emphatic examples of discordance that, to some degree, underlies the majority of MZ twin pairs. Because of the entrenched misconception that MZ twins are necessarily identical, many MZ twin pairs are mistakenly designated as dizygotic (DZ). Clinical benefits to accurate zygosity determination include correct solid organ transplantation matching, if one twin requires donation for a non-genetically mediated disease; the opportunity of preventive management for disorders that do not manifest synchronously; and better counseling to parents regarding their individually unique, and often psychologically puzzling, twin offspring. In twin pairs with complex and confusing biological origins, more detailed zygosity testing may be required. For example, intermediate trigametic and tetragametic chimeric dizygotic twins are reviewed, some of whom are, nevertheless, monochorionic (MC). Because of inter-fetal vascular anastomoses in MC twins, genetic results from blood samples may not accurately reflect discordance in solid organs. Previously, it was thought that MZ twinning was some sort of embryological fluke. However, familial monozygotic twinning is more common than suggested by the literature. Seven new families are presented in an accompanying paper. Despite the difficulties and dangers of twin pregnancy (especially so for MC twins), human twinning persists, and continues to both challenge and fascinate parents, clinicians and geneticists. © 2009 Wiley-Liss, Inc. [source]

    Monozygotic twins with idiopathic internal root resorption: A case report

    AUSTRALIAN ENDODONTIC JOURNAL, Issue 2 2010
    Daniel Urban mudr
    Abstract This study presents the first case of internal root resorption in monozygotic twins. Genetic factors have been implicated in the development of root resorption lesions. The link between interleukin (IL)-1 gene polymorphism and root resorption had been reported. However, these studies have involved external root resorption. Twin healthy 17 year old Caucasian sisters were diagnosed with internal root resorption in their upper left central incisor. Neither had a history of orofacial trauma and neither had received orthodontic treatment. The presence of IL-1,+C3953 allele is the sign of predisposed susceptibility to an exaggerated inflammatory response, including a limited feedback mechanism as a consequence of IL-1RN mutation. Most investigators agree that the listed polymorphism presents a significantly higher risk for development of pathological resorption. These were thought to be cases of true idiopathic resorption as none of the other factors related to root resorption was found. [source]

    Monozygous Twin Brothers Discordant for Photosensitive Epilepsy: First Report of Possible Visual Priming in Humans

    EPILEPSIA, Issue 9 2005
    Gerrit-Jan De Haan
    Summary:,Purpose: The interaction of genetic predisposition and the environment in the development of epilepsy is often discussed, but, aside from some animal reflex epilepsies, little evidence supports such interaction in the development of reflex epilepsy in humans. Methods: We describe the history of a 16-year-old boy in whom photosensitive epilepsy developed after a period of weekly exposures to high-intensity light flashes. Results: Both he and his clinically unaffected monozygotic twin were found to be photosensitive. Conclusions: This case report suggests that some genetic forms of human reflex epilepsy may be elicited by repeated environmental exposure to the appropriate stimulus, similar to some of the stimulus-induced epilepsies seen in animals. [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]

    Aplasia cutis congenita with skull defect in a monozygotic twin after exposure to methimazole in utero

    BIRTH DEFECTS RESEARCH, Issue 10 2007
    Hideyuki Iwayama
    Abstract BACKGROUND: Aplasia cutis congenita (ACC) is a condition in which localized or widespread areas of skin are absent at birth. Defective lesions show complete absence of all layers of skin, occasionally extending to skull or dura. ACC is etiologically heterogeneous; many different etiologies including teratogens have been documented. CASE: We describe the first reported case of a monozygotic twin with ACC after exposure to methimazole in utero. The female patient was born at 36 weeks gestation as the first child of monozygotic twins. The mother received methimazole between the 11th and 17th weeks of pregnancy because of transient hyperthyroidism. The second child did not have ACC. The patient had defects of the scalp, skull, and dura (7 × 5 cm) on the sagittal line of the parieto-occipital region. No other malformations were noted. The scalp defect has been treated daily with sterile physiological saline and petrolatum dressing in addition to intravenous antibiotics. Trafermin, a recombinant human fibroblast growth factor, was sprayed from day 6 to promote epithelialization of the scalp defect. On day 21, she had high fever due to infection of the defect lesion, which was controlled by povidone iodine dressing and intravenous antibiotics. The defect of the scalp was well healed after 6 weeks, but the skull defect remained unclosed. CONCLUSIONS: We describe a rare case of a monozygotic twin with ACC and skull defect after methimazole exposure in utero. The findings of our case suggest that methimazole is a potential teratogen of ACC. Birth Defects Research (Part A) 2007. © 2007 Wiley-Liss, Inc. [source]

    Myeloma in monozygotic twin

    BRITISH JOURNAL OF HAEMATOLOGY, Issue 6 2006
    Robert J. Cutting
    No abstract is available for this article. [source]

    Review of animal models for autism: implication of thyroid hormone

    CONGENITAL ANOMALIES, Issue 1 2006
    Miyuki Sadamatsu
    ABSTRACT,, Autism is a behaviorally defined disorder associated with characteristic impairments in social interactions and communication, as well as restricted and repetitive behaviors and interest. Its prevalence was once thought to be 2/10 000, but recently several large autism prevalence reviews revealed that the rate of occurrence was roughly 30/10 000. While it has been considered a developmental disorder, little is certain about its etiology. Neuroanatomical studies at the histological level in the brains of autistic patients provide many arguments in the etiology of autism. Results from postmortem and imaging studies have implicated many major structures of the brain including the limbic system, cerebellum, corpus callosum, basal ganglia and brainstem. There is no single biological or clinical marker for autism. While several promising candidate genes have been presented, the critical loci are yet unknown. Environmental influences such as rubella virus, valproic acid, and thalidomide exposure during pregnancy are also considered important, as concordance in monozygotic twins is less than 100% and the phenotypic expression of the disorder varies widely. It is thus hypothesized that non-genetic mechanisms contribute to the onset of autistic syndrome. In light of these ambiguities, hope is held that an animal model of autism may help elucidate matters. In this article, we overview most of the currently available animal models for autism, and propose the rat with mild and transient neonatal hypothyroidism as a novel model for autism. [source]

    The mechanism of emergenesis

    GENES, BRAIN AND BEHAVIOR, Issue 4 2006
    D. T. Lykken
    Since each individual produced by the sexual process contains a unique set of genes, very exceptional combinations of genes are unlikely to appear twice even within the same family. E. O. Wilson (1978) The intraclass correlations of monozygotic twins who were separated in infancy and reared apart (MZA twins) provide estimates of trait heritability, and the Minnesota Study of Twins Reared Apart [MISTRA: Bouchard et al. (1990), The sources of human psychological differences: the Minnesota study of twins reared apart, Science 250, 223,228] has demonstrated that MZA pairs are as similar in most respects as MZ pairs reared together. Some polygenic traits,e.g. stature, IQ, harm avoidance, negative emotionality, interest in sports,are polygenic-additive, so pairs of relatives resemble one another on the given trait in proportion to their genetic similarity. But the existence and the intensity of other important psychological traits seem to be emergent properties of gene configurations (or configurations of independent and partially genetic traits) that interact multiplicatively rather than additively. Monozygotic (MZ) twins may be strongly correlated on such emergenic traits, while the similarity of dizygotic (DZ) twins, sibs or parent,offspring pairs may be much less than half that of MZ pairs. Some emergenic traits, although strongly genetic, do not appear to run in families. MISTRA has provided at least two examples of traits for which MZA twins are strongly correlated, and DZA pairs correlate near zero, while DZ pairs reared together (DZTs) are about half as similar as MZTs. These findings suggest that even more traits may be emergenic than those already identified. Studies of adoptees reared together (who are perhaps more common than twins reared apart) may help to identify traits that are emergenic, but that also are influenced by a common rearing environment. [source]

    Genetic and environmental influences on Anxious/Depression during childhood: a study from the Netherlands Twin Register

    GENES, BRAIN AND BEHAVIOR, Issue 8 2005
    D. I. Boomsma
    For a large sample of twin pairs from the Netherlands Twins Register who were recruited at birth and followed through childhood, we obtained parental ratings of Anxious/Depression (A/D). Maternal ratings were obtained at ages 3 years (for 9025 twin pairs), 5 years (9222 pairs), 7 years (7331 pairs), 10 years (4430 pairs) and 12 years (2363 pairs). For 60,90% of the pairs, father ratings were also available. Multivariate genetic models were used to test for rater-independent and rater-specific assessments of A/D and to determine the genetic and environmental influences on individual differences in A/D at different ages. At all ages, monozygotic twins resembled each other more closely for A/D than dizygotic twins, implying genetic influences on variation in A/D. Opposite sex twin pairs resembled each other to same extent as same-sex dizygotic twins, suggesting that the same genes are expressed in boys and girls. Heritability estimates for rater-independent A/D were high in 3-year olds (76%) and decreased in size as children grew up [60% at age 5, 67% at age 7, 53% at age 10 (60% in boys) and 48% at age 12 years]. The decrease in genetic influences was accompanied by an increase in the influence of the shared family environment [absent at ages 3 and 7, 16% at age 5, 20% at age 10 (5% in boys) and 18% at age 12 years]. The agreement between parental A/D ratings was between 0.5 and 0.7, with somewhat higher correlations for the youngest group. Disagreement in ratings between the parents was not merely the result of unreliability or rater bias. Both the parents provided unique information from their own perspective on the behavior of their children. Significant influences of genetic and shared environmental factors were found for the unique parental views. At all ages, the contribution of shared environmental factors to variation in rater-specific views was higher for father ratings. Also, at all ages except age 12, the heritability estimates for the rater-specific phenotype were higher for mother ratings (59% at age 3 and decreasing to 27% at age 12 years) than for father ratings (between 14 and 29%). Differences between children, even as young as 3 years, in A/D are to a large extent due to genetic differences. As children grow up, the variation in A/D is due in equal parts to genetic and environmental influences. Anxious/Depression, unlike many other common childhood psychopathologies, is influenced by the shared family environment. These findings may provide support for why certain family therapeutic approaches are effective in the A/D spectrum of illnesses. [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]

    Genetic background of primary biliary cirrhosis

    HEPATOLOGY RESEARCH, Issue 2007
    Atsushi Tanaka
    The clustering of patients in a representative family as well as relatively high concordance rate in monozygotic twins strongly indicate that genetic factors play a crucial role in modulating primary biliary cirrhosis (PBC) by conferring susceptibility to, or providing protection from, the disease. Therefore, much like other autoimmune diseases, intensive investigations have attempted to elucidate which genes are incriminated in the etiology of PBC. So far, a number of genes, including major histocompatibility complex (MHC) class I and II, cytokines and cell surface molecules, have been examined to seek the possibility of whether single nucleotide polymorphisms (SNP) of the gene might be associated with susceptibility to PBC. Nevertheless, it appears that methodologicaldifficulties, mainly the limitation of the number of individuals tested in each study, hamper the detection of a convincing and reproducible link between genetic polymorphisms and the etiology of PBC. Also, the difference in genetic background among several ethnic groups may play a role in concealing the association. In this review, I will highlight the genetic association in PBC, and review the association of genetic polymorphisms with the etiology of PBC, which have been reported in various ethnicities. [source]

    Role of X chromosome defects in primary biliary cirrhosis

    HEPATOLOGY RESEARCH, Issue 2007
    Pietro Invernizzi
    Similar to the majority of autoimmune conditions, primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease characterized by a striking female predominance; it is characterized by high titer serum autoantibodies to mitochondrial antigens, elevated serum immunoglobulin M, progressive destruction of intrahepatic bile ducts, and ultimately liver cirrhosis and failure. Familiarity and high concordance rates for the disease among monozygotic twins strongly support the role of genetics in the disease. Experimental efforts have been dedicated by our and other research groups to investigate the role of X chromosome abnormalities (i.e. monosomyrates and inactivation patterns) in autoimmunity. Our recent work has demonstrated enhanced X monosomy in women with PBC as well as two other female-predominant autoimmune diseases, systemic sclerosis and autoimmune thyroid disease. We will review herein the most recent evidence on the role of the X chromosome in PBC onset and discuss the potential implications. Future developments of these findings will be discussed. [source]

    Nodular lymphocyte-predominant Hodgkin lymphoma and T cell histiocyte-rich large B cell lymphoma: diagnosis in two monozygotic twins

    HISTOPATHOLOGY, Issue 1 2010
    Isabel Cano
    First page of article [source]

    A comparison of early family life events amongst monozygotic twin women with lifetime anorexia nervosa, bulimia nervosa, or major depression

    INTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 8 2007
    Tracey D Wade PhD
    Abstract Objectives: To investigate the differential profile of early family life events associated with lifetime anorexia nervosa (AN), bulimia nervosa (BN), and major depression (MD). Method: Only data from the monozygotic twins (n = 622) were examined from a community sample of female twins who had participated in three waves of data collection. Eating disorder and MD diagnoses were ascertained from the Eating Disorder Examination at Wave 3 and interview at Wave 2 respectively. Early family events were ascertained from self-report measures at Waves 1 and 3. Two case control designs were used, including a comparison of women: (1) who had lifetime AN, BN, MD, and controls, and (2) twin pairs discordant for either AN, BN, or MD (where the unaffected cotwin formed the control group). Results: Across the two types of designs, compared to controls, both AN and BN were associated with more comments from the family about weight and shape when growing up. AN was uniquely associated with higher levels of paternal protection while BN was associated with higher levels of parental expectations. Conclusion: While some overlap among early life events was indicated, especially related to parental conflict and criticism, there was evidence to support some degree of nonoverlap among life events associated with AN, BN, and MD. © 2007 by Wiley Periodicals, Inc. Int J Eat Disord 2007 [source]

    The Use of Bloodhounds in Determining the Impact of Genetics and the Environment on the Expression of Human Odortype

    JOURNAL OF FORENSIC SCIENCES, Issue 5 2006
    Lisa M. Harvey Ph.D.
    ABSTRACT: Bloodhounds are used to trail fleeing felons and missing persons. In order to start a trail, the dog must be presented with a person's scent. There are many hypotheses on what a bloodhound smells while trailing. The present study attempts to identify whether human scent is genetic, and if it is influenced by one's environment. Bloodhounds trained in human scent discrimination were used to differentiate between monozygotic twins, related and nonrelated persons, living together and apart. The first test required the dogs to run blind trails after being presented with the scent of one person in the pair, while the opposite person was hidden. The second test allowed the dogs to trail one person in the pair after both people were hidden. Results appear to demonstrate that bloodhounds rely heavily on genetic cues when differentiating between people. Environmental cues do not appear to significantly aid the bloodhound in scent discrimination. [source]

    Heritability of bone density: Regional and gender differences in monozygotic twins

    JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2009
    Kevin Y. Tse
    Abstract Bone mineral density (BMD) is a measure of a person's skeletal mineral content, and assessing BMD by dual x-ray absorptiometry (DEXA) can help to diagnose diseases of low bone density. In this study, we determine the heritability of BMD in male and female monozygotic twin subjects using DEXA in 13 specific anatomical regions. In an attempt to quantify the genetic contribution of gender and skeletal region to BMD heritability, we scanned 14 pairs of identical twins using DEXA and calculated the broad-sense heritability coefficient (H2) in each of the 13 different body regions. The region of the body that was most heritable for both genders was the head (H2,,,95%). When males were compared to females, H2 values for male hip (H2,=,87%) and lower extremities (H2,=,90%) were higher than those in females (H2,=,49% and 56%, respectively). Conversely, H2 value for the female pelvis (H2,=,68%) was higher than that for males (H2,=,26%). These data show that different regions of the skeleton exhibit different degrees of heritability, and that the variation depends on gender. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:150,154, 2009 [source]

    Influence of genetics on irritable bowel syndrome, gastro-oesophageal reflux and dyspepsia: a twin study

    ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 11 2007
    A. LEMBO
    Summary Background A genetic contribution has been proposed for irritable bowel syndrome (IBS) and gastro-oesophageal reflux disease (GERD), but is controversial. No twin data exist for dyspepsia. Aim To determine the relative contribution of genetic factors in GERD, dyspepsia (upper abdominal pain) and IBS. Methods A total of 986 twin pairs (from initial mail-out response 51%). Both members completed validated symptom and psychological questionnaires; 481 monozygotic pairs [mean (s.d.) age 53 ± 5.8 years] and 505 dizygotic pairs (mean age 54 ± 5.6 years). Results Prevalence of IBS, dyspepsia and GERD was 12%, 10% and 20%, respectively. Polychoric correlation for monozygotic twins for IBS (0.47) and GERD (0.44) were both substantially larger than those for dizygotic twins (0.17 and ,0.37, respectively). Polychoric correlation was slightly lower in monozygotic than dizygotic twins for dyspepsia. Genetic modelling confirmed the independent additive genetic effects in GERD and IBS but not dyspepsia. Estimates of genetic variance were 22% for IBS, 13% for GERD and 0% for dyspepsia, but adjusting for anxiety and depression removed the statistical significance for IBS and GERD. Conclusions There is a genetic contribution to GERD and IBS but not dyspepsia; this may be mediated by the hereditability of anxiety and depression. [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]

    The Role of Melanocortin-1 Receptor Polymorphism in Skin Cancer Risk Phenotypes

    PIGMENT CELL & MELANOMA RESEARCH, Issue 3 2003
    Richard A. Sturm
    We have examined melanocortin-1 receptor (MC1R) variant allele frequencies in the general population and in a collection of adolescent dizygotic and monozygotic twins to determine statistical associations of pigmentation phenotypes with increased skin cancer risk. This included hair and skin color, freckling, mole count and sun exposed skin reflectance. Nine variants were studied and designated as either strong R (OR = 63; 95% CI 32,140) or weak r (OR = 5; 95% CI 3,11) red hair alleles. Penetrance of each MC1R variant allele was consistent with an allelic model where effects were multiplicative for red hair but additive for skin reflectance. To assess the interaction of the brown eye color gene BEY2/OCA2 on the phenotypic effects of variant MC1R alleles we imputed OCA2 genotype in the twin collection. A modifying effect of OCA2 on MC1R variant alleles was seen on constitutive skin color, freckling and mole count. In order to study the individual effects of these variants on pigmentation phenotype we have established a series of human primary melanocyte strains genotyped for the MC1R receptor. These include strains which are MC1R wild-type consensus, variant heterozygotes, and homozygotes for strong R alleles Arg151Cys and Arg160Trp. Ultrastructural analysis demonstrated that only consensus strains contained stage III and IV melanosomes in their terminal dendrites whereas Arg151Cys and Arg160Trp homozygous strains contained only immature stage I and II melanosomes. Such genetic association studies combined with the functional analysis of MC1R variant alleles in melanocytic cells should provide a link in understanding the association between pigmentary phototypes and skin cancer risk. [source]

    Transient neonatal diabetes mellitus type 1,

    AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 3 2010
    Deborah J.G. Mackay
    Abstract Transient neonatal diabetes mellitus type 1 (TNDM1) is a rare but remarkable form of diabetes which presents in infancy, resolves in the first months of life, but then frequently recurs in later life. It is caused by overexpression of the imprinted genes PLAGL1 and HYMAI on human chromosome 6q24. The expression of these genes is normally restricted to the paternal allele as a result of maternal DNA methylation. TNDM1 is not associated with mutation of PLAGL1 or HYMAI, but rather with their overexpression via uniparental disomy, chromosome duplication, or relaxation of imprinting. Study of patients with TNDM1 has provided valuable insights into the causes of imprinting disorders. Over half of patients with maternal hypomethylation at the TNDM1 locus have additional hypomethylation of other maternally methylated imprinted genes throughout the genome, and the majority of these patients have mutations in the transcription factor ZFP57. TNDM1 with maternal hypomethylation has also been observed in patients conceived by assisted reproduction, and in discordant monozygotic twins. The variable clinical features of TNDM1 may be associated with variation in the nature of the underlying epigenetic and genetic mutations, and future study of this disorder is likely to yield further insights not only into the biological mechanisms of imprinting, but also into the contribution of epigenetics to diabetes. © 2010 Wiley-Liss, Inc. [source]

    Non-identical monozygotic twins, intermediate twin types, zygosity testing, and the non-random nature of monozygotic twinning: A review,

    AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 2 2009
    Geoffrey Machin
    Abstract Monozygotic twins (MZ) are rarely absolutely "identical." This review discusses the types of genetic/epigenetic and prenatal environmental post-zygotic mechanisms that cause discordance within such twin pairs. Some of these mechanisms,ranging from heterokaryotypia to skewed X-chromosome inactivation,may cause extreme discordance, but these extremes are merely the more emphatic examples of discordance that, to some degree, underlies the majority of MZ twin pairs. Because of the entrenched misconception that MZ twins are necessarily identical, many MZ twin pairs are mistakenly designated as dizygotic (DZ). Clinical benefits to accurate zygosity determination include correct solid organ transplantation matching, if one twin requires donation for a non-genetically mediated disease; the opportunity of preventive management for disorders that do not manifest synchronously; and better counseling to parents regarding their individually unique, and often psychologically puzzling, twin offspring. In twin pairs with complex and confusing biological origins, more detailed zygosity testing may be required. For example, intermediate trigametic and tetragametic chimeric dizygotic twins are reviewed, some of whom are, nevertheless, monochorionic (MC). Because of inter-fetal vascular anastomoses in MC twins, genetic results from blood samples may not accurately reflect discordance in solid organs. Previously, it was thought that MZ twinning was some sort of embryological fluke. However, familial monozygotic twinning is more common than suggested by the literature. Seven new families are presented in an accompanying paper. Despite the difficulties and dangers of twin pregnancy (especially so for MC twins), human twinning persists, and continues to both challenge and fascinate parents, clinicians and geneticists. © 2009 Wiley-Liss, Inc. [source]

    Not really identical: Epigenetic differences in monozygotic twins and implications for twin studies in psychiatry,

    AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 2 2009
    F. Nipa Haque
    Abstract Classical twin studies in the field of psychiatry generally fall into one of two categories: (1) those designed to identify environmental risk factors causing discordance in monozygotic (MZ) twins and (2) those geared towards identifying genetic risk factors. However, neither environment nor differences in DNA sequence can fully account for phenotypic discordance among MZ twins. The field of epigenetics , DNA modifications that can affect gene expression , offers new models to understand discordance in MZ twins. In the past, MZ twins were regarded as genetically-identical controls for differing environmental conditions. In contrast, the evolving current concept is that epigenetic differences between MZ twins may modulate differences in diverse phenotype, from disease to personality. In this article, we review some twin studies, and discuss the dynamic interactions between stochastic, environmental, and epigenetic variables that influence neurobiological phenotypes. © 2009 Wiley-Liss, Inc. [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]

    Early prenatal diagnosis of concordant posterior urethral valves in male monochorionic twins

    PRENATAL DIAGNOSIS, Issue 1 2006
    G. M. Maruotti
    Abstract The association between monozygotic twins and posterior urethral valves (PUV) in postnatal life has been thoroughly described. In the fetus, the prenatal recognition of PUV is feasible. However, it has been repeatedly reported in singletons but never in monochorionic twins. We describe two cases of early prenatal diagnosis of concordant PUVs in monochorionic twins. In one of the sets, the expression of the disease was different for each twin. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    A study of the occurrence of monochorionic and monozygotic twinning in the pig

    ANIMAL GENETICS, Issue 1 2009
    D. Bjerre
    Summary In humans as well as in most farm animals, monozygotic twins have been described. Nevertheless, only a few reports of twinning in the pig have been published. It has been suggested that monozygotic twins are formed during the first 14 days of pregnancy. This monozygotic twin study includes the investigation of porcine monochorionic embryos from 76 sows at days 26,29 post-insemination (p.i.), as well as an examination of 10 whole litters at days 21,22 p.i. In the former group, 29% of the sows carried monochorionic embryos. Based on DNA profiling using microsatellite markers, one monozygotic twin pair was found among these embryos. In the latter group, three monozygotic twin pairs were identified. Thus, it can be concluded that although the occurrence of monozygotic twins in pigs is a sporadic event, the fusion of extra-embryonic membranes is relatively common. [source]