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PubMed2005

[Difference analysis of genome-wide DNA methylation status of CpG islands between the monozygotic twins with disconcordant phenotypes of chronic hepatitis B virus infection].

OBJECTIVE: To analyse the difference of genome-wide DNA methylation status of CpG island between the monozygotic twins with disconcordant phenotype of HBV infection and to discover possible differentially methylated genes. METHODS: Modified AIMS (amplification of inter-methylated sites) method was adopted. According to the frequent sites of CpG islands (-CGCG- and -CCGG-), three groups of isochizomers with distinct methylation sensitivity (Sma I-Xma I, Hpa II-Msp I and BssH II-Pau I/BseP I) were used to modify the AIMS method. The modified AIMS method combined with Personal Molecular Imager FX system analysis and radioautographic analysis was used to make the global detection of the methylome of CpG islands. Multiple anonymous bands were compared between the twins with the Quantity One bio-soft. The different bands were cloned into T vectors and positive clones were sequenced. BLAST analysis of positive clone sequences was conducted to give the clues for the differential methylated genes between monozygotic twins with discordant phenotype of HBV infection. RESULTS: Nearly the same bands were found between one pair of twins with concordant phenotype of HBV infection. Different methylated bands were found not only between monozygotic twins with concordant phenotype but also between those with disconcordant phenotype. More differential methylated bands were found in the latter groups. By BLAST analysis with sequences of differential methylated bands, four possible genes were got. These genes might relate to the monozygotic twins with disconcordant phenotype of chronic HBV infection. CONCLUSION: Differential methylation of genes occurs in monozygotic twins with discordant phenotype of HBV infection. Whether these changes are involved in the pathogenesis of different phenotypes needs further elucidation.

Adolescent↗
PubMed2024

Fabry disease in female monozygotic twins with complex intronic haplotype variants: a case report.

BACKGROUND: Fabry disease is an X-linked lysosomal storage disease caused by the impairment of α-galactosidase A. The complex intronic haplotype (CIH) variants, located in promoter and intronic regulatory lesions, has been found in patients with classical forms of Fabry disease. We present a case of Fabry disease in female monozygotic twins exhibiting the CIH mutation and classical manifestations. CASE PRESENTATION: A 61-year-old woman with a history of stroke, carotid artery occlusion, hypertrophic cardiomyopathy, and chronic kidney disease was referred to the nephrology clinic for management of her chronic kidney disease. Her monozygotic twin sister also presented with hypertrophic cardiomyopathy, atrial flutter, carotid stenosis, and proteinuria. Clinical symptoms and a comprehensive family history strongly suggested the presence of Fabry disease. Genetic analysis revealed the presence of 5 variants within a complex intronic haplotype (CIH): c.-10 C > T, c.369 + 990 C > A, c.370 - 81_370-77delCAGCC, c.640-16 A > G, and c.1000-22 C > T. We conducted a review of the patient's previous kidney biopsy findings, which demonstrated the presence of lamellated inclusion bodies in electron microscopy. Remarkably, both the monozygotic twin sister and her son exhibited the same genetic mutation. Enzyme replacement therapy was initiated for the patient. Her kidney function decreased throughout a thorough 2-year follow-up period, while there was a slight decrease in the left ventricular mass index. CONCLUSIONS: This is the first reported case of female monozygotic twins with the CIH variants representing cardiac, cerebrovascular, and renal manifestations suggestive of Fabry disease.

Humans↗
PubMed1993

Clinical, neuroimaging, and environmental risk differences in monozygotic female twins appearing discordant for dementia of the Alzheimer type.

OBJECTIVE: The study of monozygotic twins can elucidate possible environmental causes for a disease in genetically identical subjects. To this end, we studied a pair of monozygotic female twins appearing discordant for dementia of the Alzheimer type (DAT). DESIGN: Clinical and neuroimaging findings were compared in terms of potential environmental risk factors. SETTING: University referral center. PARTICIPANTS: An 81-year-old female monozygotic twin pair. OUTCOME MEASURES: Clinical assessments, standardized rating scales, and brain imaging studies, including magnetic resonance imaging, positron emission tomography, and electroencephalography, were performed. Neuropsychological tests were performed initially and after 1 year. RESULTS: Although DAT was confirmed clinically in only one twin, neuropsychological and brain imaging studies suggested that the unaffected twin may be developing the prodrome of DAT. The twins' varied life histories suggest that environmental risk factors may contribute to apparent discordance for DAT and possible delay in disease onset for the currently nondemented twin. CONCLUSIONS: These results suggest that both genetic and nongenetic factors influence disease onset and expression. Moreover, review of previous reports of monozygotic twin pairs concordant or discordant for Alzheimer's disease, with adequate family history data, suggest a pattern indicating interactions among age at dementia onset, sex, and familiarity. Such patterns point to hypotheses regarding neurobiologically meaningful Alzheimer's disease subgroups.

Aged↗
PubMed1986

Parkinson's disease in monozygotic twins.

Recent studies of twins have demonstrated an unexpectedly low concordance of Parkinson's disease in monozygotic twins. Only two monozygotic twin pairs concordant for it have been reported. However, both pairs were atypical because of an early age at onset and other unusual features. We studied a monozygotic twin pair concordant for typical Parkinson's disease. The brothers have lived apart for forty years. The onset of tremor occurred three months apart, at age 71. The progression of the symptoms has been identical. Although one of the twins is more severely affected, both have typical manifestations of Parkinson's disease that respond well to dopaminergic medication. The occurrence of Parkinson's disease in these monozygotic twins suggests that genetic susceptibility is important in the tremor-dominant variety of Parkinson's disease.

Aged↗
PubMed1984

New evidence for monozygotic twins in the mouse: twinning initiated in the late blastocyst can account for mirror image asymmetries.

The 11.5-day twin mice reported here support one of the classically described mechanisms for mammalian monozygotic twinning: subdivision of the blastocyst inner cell mass at the stage of proamnion cavitation. This particular method for monozygotic twinning has the attraction of providing a hypothesis for mirror image translocation of asymmetric traits. Monozygotic twins in laboratory rodents at or near parturition have not been identified and only two prior descriptions, for 7.5- and 9.5-day mouse embryos, have been found in the literature. Experimentally induced twins having identical heredity, i.e., clones, would enable study of heritable and environmental regulation of the components of discordance. A set of twin mouse embryos at 11.5 days of gestation within a common yolk sac, and with shared vitelline and allantoic circulations, provides direct evidence that monozygotic twin mice can survive rotation within the common yolk sac and suggests a reasonable probability that they can survive to term.

Animals↗
PubMed1998

Assisted hatching reduces the age-related decline in IVF outcome in women younger than age 43 without increasing miscarriage or monozygotic twinning.

PURPOSE: Our purpose was to examine the benefits of assisted hatching in our program and to determine whether the procedure increases the implantation of nonviable embryos or monozygotic twinning. METHODS: Consecutive in vitro fertilization cycles using assisted hatching were compared with historical controls. The impact of assisted hatching was analyzed according to the woman's age. Outcome measures were clinical pregnancy, implantation rate, delivery rate, multiple pregnancy, spontaneous abortion, and incidence of monozygotic twins. RESULTS: The implantation rate was increased in women aged 35-39 and markedly increased in women aged 40-42. There was no change in spontaneous abortions and no increase in monozygotic twins. CONCLUSIONS: Assisted hatching is a safe and highly effective adjunct to in vitro fertilization for women aged 35-42 and did not increase spontaneous abortion or monozygotic twinning.

Abortion, Spontaneous↗
PubMed2000

Insulin sensitivity and insulin secretion in monozygotic and dizygotic twins.

AIMS/HYPOTHESIS: To estimate the heritability of insulin sensitivity and insulin secretion, both of which are considered to contribute to the development of Type II (non-insulin-dependent) diabetes mellitus. METHODS: Intraclass correlation coefficients and heritability estimates for insulin sensitivity (euglycaemic clamp) as well as first-phase and late-phase insulin secretion (intravenous glucose tolerance test) were calculated in 21 monozygotic and 20 dizygotic twin pairs of the same sex between 54 and 72 years of age. RESULTS: Intrapair correlations for all traits were consistently higher in monozygotic than in dizygotic pairs. Insulin secretion correlated significantly only between monozygotic (first-phase r = 0.55; p = 0.003 and late-phase r = 0.66; p < 0.001) twins giving heritability estimates of 0.55 and 0.58, respectively. Insulin-stimulated glucose uptake showed a more modest correlation between monozygotic twins (r = 0.46; p = 0.015). The heritability estimate was 0.37. The heritability estimate for waist-to-hip ratio was 0.76 in female and 0.70 in male twins. CONCLUSION/INTERPRETATION: Genetic variability seems to contribute to the variance of insulin sensitivity as well as of insulin secretion. In the current study, genetic variance accounted almost 60% for the variance in glucose-stimulated insulin secretion and almost 40% for the variance in insulin-stimulated glucose uptake. Our data is also compatible with findings in monogenic forms of diabetes in which genetic defects in insulin secretion play a predominant part in the pathogenesis of hyperglycaemia.

Aged↗
PubMed2005

Quantitative ultrasound of the hand phalanges in a cohort of monozygotic twins: influence of genetic and environmental factors.

OBJECTIVE: Our objective was to evaluate the similarities and differences in bone mass and structure between pairs of monozygotic twins as measured by means of the quantitative ultrasound (QUS) technique. DESIGN: A cohort of monozygotic twins was measured by QUS of the hand phalanges using the DBM sonic bone profiler (IGEA, Carpi, Italy). The parameters studied were amplitude-dependent speed of sound (AD-SoS), ultrasound bone profile index (UBPI), signal dynamics (SDy) and bone transmission time (BTT). Linear correlation coefficients, multivariate linear analysis and the ANOVA test were used to assess intrapair associations between variables and to determine which factors influence the intrapair differences in QUS variables. PATIENTS: One hundred and six pairs of monozygotic twins were enrolled in the study, 68 females and 38 males in the age range 5 to 71 years. RESULTS: Significant intrapair correlations were obtained in the whole population and separately for males and females, regarding height ( r =0.98-0.99, p <0.0001), weight ( r =0.95-0.96, p <0.0001), AD-SoS ( r =0.90-0.92, p <0.0001), BTT ( r =0.94-0.95, p <0.0001) and other QUS parameters ( r >0.74, p <0.0001). Multivariate analysis revealed that intrapair differences between AD-SoS, SDy, UBPI and BTT are significantly influenced by age in the whole population and in the female population. Furthermore, the ANOVA test showed, for the female group, a significant increase in the intrapair differences in SDy and UBPI above 40 years. CONCLUSIONS: A relative contribution of genetic factors to skeletal status could be observed by phalangeal QUS measurement in monozygotic twins. A significant increase in the intrapair difference in QUS parameters with increasing age and onset of menopause also suggests the importance of environmental factors in the female twin population.

Adolescent↗
PubMed1995

A mirror image of the first and second branchial arch syndrome associated with cleft lip and palate in monozygotic twins.

A rare case of monozygotic twins revealing a mirror image of the first and second branchial arch syndrome with accessory ear and hemifacial microsomia, associated with unilateral cleft lip and palate, is presented. Although the concordance and/or discordance rate of monozygotic or dizygotic twins with cleft lip and palate is well reported, that of twinning of the first and second branchial arch syndrome has been very rarely described. First and second branchial arch syndrome occurs sporadically but cleft lip and palate are strongly related to the influence of environmental factors with a considerable hereditary tendency. The study of twinning of congenital anomalies is important in the investigation of the pathogenesis of genetic and environmental effects. The twins were diagnosed as monozygotic with almost complete certainty by ABO blood typing, HLA typing, finger prints, and DNA typing. Concordance was noticed, which suggests a hereditary tendency. Since concordance in these monozygotic twins was exhibited by a precise mirror image of first and second branchial arch syndrome, spinal scoliosis and cleft lip and palate, it is possible that an environmental factor induced these complex anomalies.

Abnormalities, Multiple↗
PubMed1979

Hirschsprung's disease discordant in monozygotic twins: a study of possible environmental factors in the production of colonic aganglionosis.

The occurrence of Hirschsprung's disease, with histologically verified colonic aganglionosis, in only 1 of 2 prematurely born and presumed identical (monozygotic) twins is reported. The occurrence of monozygotic twinning was supported by the observed sharing of a single and common placenta and by ABO and HLA identity of peripheral blood erythrocytes and leukocytes. The affected twin was of a slightly lower birth weight and experienced early respiratory distress, necrotizing enterocolotis, and more prolonged umbilical artery catheterization (no encountered in the unaffected twin). This, to the authors' knowledge, is the first reported occurrence of Hirschsprung's disease discordant in monozygotic twins. The literature relating to genetic and environmental factors in clinical and experimental colonic aganglionosis is reviewed and speculation is presented regarding the occurrence of colonic aganglionosis discordant in monozygotic twins as reported here.

ABO Blood-Group System↗
PubMed2006

Intrapair differences in hippocampal volume in monozygotic twins discordant for the risk for anxiety and depression.

BACKGROUND: Current biological psychiatric models assume that genetic and environmental risk factors for anxiety and depression act on the same brain structures. METHODS: To test this assumption, we assessed brain anatomy by using optimized voxel-based morphometry on magnetic resonance images obtained in monozygotic twin pairs who were discordant for the risk of anxiety and depression (n = 10 pairs) and in monozygotic twin pairs who were concordant for high (n = 7 pairs) or low (n = 15 pairs) risk for anxiety and depression. RESULTS: We observed volume reductions in the temporal lobe, most notably in the left posterior hippocampal region in subjects at high risk for anxiety and depression, but exclusively in the intrapair comparison of discordant monozygotic twins. Because monozygotic twins are genetically identical, any discordance in their risk for anxiety and depression and hippocampal volume must arise from differential exposure to environmental influences. A group comparison between pairs concordant for low or high risk, which is more likely to reflect differences in genetic vulnerability, did not show reduced temporal-lobe and posterior hippocampal volumes in the pairs at high risk for anxiety and depression. CONCLUSIONS: This pattern of results suggests that damage to temporal-lobe structures may be specific to an environmentally driven etiology of anxiety and depression.

Adolescent↗
PubMed2005

CARD15/NOD2 polymorphisms do not explain concordance of Crohn's disease in Swedish monozygotic twins.

BACKGROUND: CARD15/NOD2 polymorphisms are associated with Crohn's disease. There is a high concordance for disease and disease phenotype in monozygotic twin pairs with Crohn's disease. AIM: We studied CARD15/NOD2 polymorphisms in a Swedish, population-based cohort of monozygotic twins with Crohn's disease to assess whether these variants explain disease concordance. SUBJECTS AND METHODS: Twenty-nine monozygotic twin pairs (concordant n=9, discordant n=20) with Crohn's disease and 192 healthy controls were investigated for the CARD15/NOD2 variants Arg702Trp, Gly908Arg and Leu1007fsinsC. RESULTS: CARD15/NOD2 mutations were found in 5/38 (13%) twins with Crohn's disease, corresponding to a total allele frequency of 6.6%. Only 2/9 concordant twin pairs carried any of the variants and the remaining seven were wild type genotype. The total allele frequency was 4.4 times higher (95% confidence interval 1.0-21.5, p=0.06) in concordant twins than in discordant ones, 11.1% versus 2.5%. In healthy controls the total allele frequency was 2.6%. CONCLUSIONS: CARD15/NOD2 polymorphisms contribute but do not alone explain concordance of Crohn's disease in monozygotic twins and, at least in a Swedish population, other polymorphisms are required. The low occurrence of CARD15/NOD2 mutations in the study and other Northern European populations suggests that these variants are of less importance in Northern Europe.

Adolescent↗
PubMed1999

Comparative corneal topography and refractive variables in monozygotic and dizygotic twins.

PURPOSE: To investigate the role of heredity in determining corneal shape, axial length, and overall refractive error. METHODS: Twenty monozygotic and 19 dizygotic twin pairs, age 12 to 73 years, were enrolled in the study. Zygosity was determined by physical similarity and by responses to questions adapted from surveys. Two twin pairs were excluded because of undetermined zygosity and one pair because of keratoconus (both siblings). Refractive error was determined by an automated refractor. Manifest refraction was also recorded, as well as cycloplegic refraction in subjects under age 18 years. Corneal topography data and manual keratometer readings were also obtained. Axial lengths were determined by A-scan ultrasound. Data were analyzed by Student t tests only in the right eye. Left-eye data were comparable for all variables. RESULTS: Mean intrapair difference in refractive error (spherical equivalent) was less for monozygotic than for dizygotic twins (RE: 0.41 vs 1.53; P = .001). Mean intrapair difference in axial length was less for monozygotic twins (RE: 0.39 vs 0.76 mm; P = .031). Corneal topography data (power and meridian) in all zones (3, 5, and 7 mm) also showed smaller mean differences among monozygotic pairs than dizygotic, but the difference was statistically significant only for the 5-mm zone. In addition, most Holladay Diagnostic Summary variables that were studied did not show any statistically significant differences. CONCLUSIONS: Axial length and overall refractive error have a significant genetic basis. Corneal topography data appear to have other overriding determining factors for several of the variables studied.

Adolescent↗
PubMedDate not supplied

Concordance of strabismic phenotypes in monozygotic versus multizygotic twins and other multiple births.

PURPOSE: The concordance of strabismic phenotypes was examined in monozygotic versus multizygotic twins and other multiple births to study the role of genetic background in different types of commitant strabismus. METHODS: Medical charts of 45 consecutive pairs of twins (16 monozygotic and 18 dizygotic twins, and 11 with unknown zygosity), 3 sets of triplets (one monozygotic and 2 trizygotic triplets), and one set of quadruzygotic quadruplets examined at 6 institutions between 1973 and 1999 were reviewed retrospectively. The concordance was defined as both or all members having either esotropia or exotropia in common. RESULTS: The concordance of strabismic phenotypes was noted in 33 of 49 pairs or sets (67.3%): 14 of 17 monozygotic twins or triplets (82.4%), 10 of 21 multizygotic twins, triplets, or quadruplets (47.6%), and 9 of 11 twins with unknown zygosity (81.8%). The concordance rate was significantly higher in monozygosity than in multizygosity (P =.043, Fisher exact probability test). The predominant concordant phenotypes in monozygosity were accommodative esotropia and intermittent exotropia. CONCLUSION: A high concordance rate of strabismic phenotypes, predominantly of accommodative esotropia and intermittent exotropia in monozygosity, suggests the genetic background for these types of strabismus.

Diseases in Twins↗
PubMed1996

An unusual case of monozygotic epigastric heteropagus twinning.

Epigastric heteropagus refers to unequal and asymmetric conjoined twins in which the dependent component (parasite) is smaller and usually attached to the epigastrium of the dominant component (autosite). Epigastric heteropagus is a very rare type of conjoined twins. It is generally assumed that conjoined twins represent a form of monozygotic twinning, but there has been no confirmation of this monozygotic hypothesis. Epigastric heteropagus twins differ in several ways from symmetrical conjoined twins. These include male preponderance, and no major connection of vessels, bowels, or bones. These significant characteristics suggest to the authors that the fusion of two fertilized ova and the atrophy of one fetus resulted in this interesting malformation. However, a DNA study indicated monozygotic origin in their case. The possible pathogenesis was ischemic atrophy of the body structure of the monozygotic conjoined twins at an early gestational age.

DNA↗
PubMed1998

Allospecific helper T-lymphocyte repertoire in monozygotic twins.

In the course of maturation in the thymus there is a selection of T lymphocytes based on the avidity between their T-cell receptors and HLA/peptide complexes expressed on stromal thymic cells. The repertoire of mature T lymphocytes is further modulated by encounters with foreign antigens. Thus, the antigen specific repertoire of the peripheral T-lymphocyte pool is determined by genetic and environmental factors. We recently reported that pairs of monozygotic twins often display significant differences in their allospecific cytotoxic T-cell repertoire, suggesting an important role of confrontation with foreign antigens on the CD8+ T-cell repertoire. We have now performed similar studies on the repertoire of allospecific CD4+ T lymphocytes. Using positively selected CD4+ T cells in limiting dilution analyses we compared the differences in the allospecific helper T-lymphocyte precursor frequencies (HTLpf) between pairs of genetically identical monozygotic twins and pairs of unrelated, HLA disparate individuals. We found that all monozygotic twin pairs and most unrelated pairs had similar HTLpf to the same stimulator, i.e. the 95% confidence intervals were overlapping. However, when studied in greater detail, the differences in HTLpf within monozygotic twin pairs were found to be significantly smaller than the differences within pairs of unrelated responders. Thus, we find evidence of an influence by environmental antigens also on the repertoire of allospecific CD4+ T cells, but polymorphic genetic factors seem to be more important here than for the repertoire of allospecific CD8+ T cells.

Adult↗
PubMed2001

Monozygotic twinning after assisted reproductive techniques: a phenomenon independent of micromanipulation.

A 3 year retrospective analysis was conducted of pregnancies achieved after various assisted reproductive treatment modalities in our infertility practice, to calculate and compare the rates of monozygotic twinning (MZT). A total of 731 pregnancies achieved after various assisted reproduction treatments were reviewed. Gonadotrophin therapy for induction of ovulation and controlled ovarian hyperstimulation (COH) yielded 129 clinical pregnancies. Conventional IVF yielded 139 pregnancies. IVF and intracytoplasmic sperm injection (ICSI) with or without assisted hatching (AH) yielded 463 pregnancies, all during the same time period. The rates of multiple pregnancy (monozygotic and dizygotic) twins and triplets were recorded. MZT was found in 1.5% of ovulation induction or COH pregnancies (2/129). The incidence of MZT after conventional IVF was 0.72% (1/139). After IVF-ICSI/AH, MZT was found in 0.86% (4/463). The overall rate of MZT was 0.95% (7/731). Five cases were dizygotic triplets and two cases were monozygotic twins. We found the rate of MZT after assisted reproduction treatment increased more than two-fold over the background rate in the general population. Dizygotic triplets were found more often than monozygotic twins. The rate of MZT was consistently increased, irrespective of treatment modality or micromanipulation. This may signify that the aetiology of increased MZT after assisted reproduction is the gonadotrophin treatment rather than in-vitro conditions, micromanipulation, or multiple embryo transfer.

Adult↗
PubMed1994

Lack of evidence for a superantigen in lymphocytes from HIV-discordant monozygotic twins.

OBJECTIVE: An HIV-associated superantigen (SAg) has been hypothesized. Here we test whether an SAg is functionally detectable in peripheral blood mononuclear cells (PBMC) from monozygotic twins discordant for HIV infection. DESIGN AND METHODS: The V beta selective T-cell depletion found in minor lymphocyte stimulation (Mls)-positive mice is caused by an SAg encoded by the mouse mammary tumour virus. Mls is a locus whose gene product stimulates a mixed lymphocyte reaction (MLR) in mice strains identical at the major histocompatibility complex locus. If an SAg is present in PBMC and/or sorted CD4+ cells from one HIV-infected monozygotic twin, it would stimulate PBMC from the corresponding healthy monozygotic twin in an MLR. In addition, if an SAg causes V beta-selective T-cell depletion in AIDS patients, a differential proliferation to a panel of staphylococcal enterotoxins (SE) of T lymphocytes from healthy and HIV-infected monozygotic twins should become measurable. RESULTS: No positive MLR or significant differences in the SE-driven proliferation between the healthy and the HIV-infected twins were observed. CONCLUSIONS: Our results suggest that PBMC from the two HIV-infected twins do not express a functionally detectable SAg.

Adult↗