Novel autopsy and genetic findings in an acardiac twin: case report and literature review.

Twin reversed arterial perfusion (TRAP) sequence is a rare complication of monochorionic twinning whereby a donor twin perfuses an acardiac twin via aberrant vascular anastomoses. The resulting paradoxical retrograde blood flow supplying the acardiac twin is oxygen-poor, leading to some of the most severe malformations encountered in humans. Though the first descriptions of acardiac twins date back to at least the 16th century, the pathophysiologic processes which underpin the development of TRAP sequence are still being elucidated. Theories on the pathogenesis of TRAP sequence include deficiencies intrinsic to the embryo and primary abnormalities of the placental vasculature. Autopsy studies continue to provide clues to the underlying pathogenesis of TRAP sequence, and the characterization of the spectrum of manifestations that can be observed in acardiac twins. Herein, we present the clinical, autopsy, and molecular findings in a unique case of TRAP sequence. Novel findings include a primitive cloaca-like structure and chromosomal aberrations involving 6q11.1 and 15q25.1.

Novel autopsy and genetic findings in an acardiac twin: case report and literature review

ABSTRACT Twin reversed arterial perfusion (TRAP) sequence is a rare complication of monochorionic twinning whereby a donor twin perfuses an acardiac twin via aberrant vascular anastomoses. The resulting paradoxical retrograde blood flow supplying the acardiac twin is oxygen-poor, leading to some of the most severe malformations encountered in humans. Though the first descriptions of acardiac twins date back to at least the 16th century, the pathophysiologic processes which underpin the development of TRAP sequence are still being elucidated. Theories on the pathogenesis of TRAP sequence include deficiencies intrinsic to the embryo and primary abnormalities of the placental vasculature. Autopsy studies continue to provide clues to the underlying pathogenesis of TRAP sequence, and the characterization of the spectrum of manifestations that can be observed in acardiac twins. Herein, we present the clinical, autopsy, and molecular findings in a unique case of TRAP sequence. Novel findings include a primitive cloaca-like structure and chromosomal aberrations involving 6q11.1 and 15q25.1.

Guideline No. 440: Management of Monochorionic Twin Pregnancies.

OBJECTIVE: This guideline reviews the evidence-based management of normal and complicated monochorionic twin pregnancies. TARGET POPULATION: Women with monochorionic twin or higher order multiple pregnancies. BENEFITS, HARMS, AND COSTS: Implementation of these recommendations should improve the management of both complicated and uncomplicated monochorionic (and higher order multiple) twin pregnancies. They will help users monitor monochorionic twin pregnancies appropriately and identify and manage monochorionic twin complications optimally in a timely manner, thereby reducing perinatal morbidity and mortality. These recommendations entail more frequent ultrasound monitoring of monochorionic twins compared to dichorionic twins. EVIDENCE: Published literature was retrieved through searches of PubMed and the Cochrane Library using appropriate MeSH headings (Twins, Monozygotic; Ultrasonography, Prenatal; Placenta; Fetofetal Transfusion; Fetal Death; Fetal Growth Retardation). Results were restricted to systematic reviews, randomized controlled clinical trials, and observational studies. There were no date limits, but results were limited to English or French language materials. VALIDATION METHODS: The content and recommendations were drafted and agreed upon by the principal authors. The Board of the SOGC approved the final draft for publication. The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations). INTENDED AUDIENCE: Maternal-fetal medicine specialists, obstetricians, radiologists, sonographers, family physicians, nurses, midwives, residents, and other health care providers who care for women with monochorionic twin or higher order multiple pregnancies. TWEETABLE ABSTRACT: Canadian (SOGC) guidelines for the diagnosis, ultrasound surveillance and management of monochorionic twin pregnancy complications, including TTTS, TAPS, sFGR (sIUGR), acardiac (TRAP), monoamniotic twins and intrauterine death of one MC twin. SUMMARY STATEMENTS: RECOMMENDATIONS.

Comparison of Prenatal and Neonatal Outcomes of Selective Fetal Growth Restriction in Monochorionic Twin Pregnancies with or Without Twin-to-Twin Transfusion Syndrome After Radiofrequency Ablation.

Background: This study aimed to investigate and compare the prenatal and neonatal outcomes of monochorionic twin pregnancies complicated with fetal growth restriction (sFGR) with or without twin-to-twin transfusion syndrome (TTTS) after cord occlusion by radiofrequency ablation (RFA). Methods: This prospective cross-sectional study was conducted in women with monochorionic twin pregnancies of 16 to 26 weeks of gestational age (GA) in an academic hospital from 2016 to 2020. Demographic and obstetrical characteristics such as cervical length, GA of RFA and delivery, amnioreduction, cesarean section (C/S) rate, and maximum vertical pocket as well as prenatal, neonatal, and maternal outcomes were evaluated and compared between groups using Statistical Package for the Social Sciences (SPSS). Mann-Whitney U test or independent t test was used for quantitative data and Chi square test was applied for comparing qualitative variables. The significance level of tests was 0.05. Results: Totally 213 (106 sFGR and 107 TTTS+sFGR) cases were enrolled. The mean of maternal age (P=0.787), body mass index (P=0.932), gestational age at RFA (P=0.265), as well as gestational age of delivery (P=0.482), and C/S rate (P=0.124) were not significant between the two groups, but a significant difference (P<0.001) in cervical length was observed between the two groups. No significant differences were found in newborn and fetal outcomes such as fetal demise (P=0.827), PPROM (P=0.233), abortion (P=0.088), and admission to intensive care unit (P=0.822) between the groups. Conclusion: Although worse fetal and neonatal outcomes were expected in the TTTS+sFGR group after RFA, no significant difference was observed between groups.

Association of Vitamin D Supplementation in Cardiorespiratory Fitness and Muscle Strength in Adult Twins: A Randomized Controlled Trial.

Although vitamin D is related to cardiorespiratory fitness and muscle strength, there is no evidence in the literature about the genetic influence of the response to vitamin D supplementation and improvements in these parameters. Therefore, we evaluate the effect of longitudinal supplementation of vitamin D on parameters of physical fitness in monozygotic twins. In total, 74 participants were included, with a mean age of 25 years, divided into two groups, one group received supplementation with cholecalciferol for 60 days and the other group did not. Cardiorespiratory fitness and muscle strength were measured before and after supplementation through maximal treadmill tests and dynamometry, respectively. Wilcoxon tests were used to compare intragroup results and the Mann-Whitney test to examine intergroup differences. There was an increase in the serum concentration of vitamin D in participants who ingested the supplementation. Cardiorespiratory fitness improved after supplementation through increases in the values of maximum oxygen consumption of 28% (p < .001). Muscle strength in left hand grip increased 18% in participants who received the supplement (p = .007). Sixty days of cholecalciferol supplementation improved cardiorespiratory fitness and upper limb muscle strength.

Concordance of Congenital Heart Defect in Monozygotic Twins in Brazil

Abstract Tetralogy of Fallot (TOF) consists of four cardiac changes: interventricular communication, pulmonary stenosis, aortic dextroposition and right ventricular hypertrophy. The prevalence is 0.1 per 1,000 live births. A primiparous mother with gestational age of 38 weeks came to the emergency. At the time, it was verified in her twin pregnancy that one fetus had TOF, thus a pregnancy interruption was scheduled for the following day. In the neonatal physical examination of both, localized acrocyanosis, regular heart rhythm with the presence of a heart murmur, and good peripheral perfusion were found. The echocardiogram of twin 1 revealed: patent foramen ovale; a wide perimembranous interventricular communication of misalignment, with the aorta riding the septum by 50%; hypertrophied and long infundibulum with pulmonary infundibulo-valvular stenosis, with a maximum systolic gradient of 66 mm Hg; both pulmonary arteries presented dimensions of 0.35 mm; pulmonary valve annulus: 0.56 mm; and patent ductus arteriosus measuring 0.19 mm. The echocardiogram of twin 2 showed: patent foramen ovale; a wide perimembranous interventricular communication of misalignment, with the aorta riding the septum by 50%; hypertrophied infundibulum with stenosis pulmonary infundibulo-valve, with a maximum systolic gradient of 33 mm Hg; reduced confluent pulmonary arteries; right pulmonary artery measuring 0.40 mm and left pulmonary artery measuring 0.55 mm; pulmonary valve annulus measuring 0.72 mm; a closed arterial canal, and mild aortic regurgitation. Tetralogy of Fallot is a multifaceted syndrome with a high prevalence in pediatrics. This case is the first case of congenital heart defect concordance for TOF in monozygotic twins in Brazil.

Outcome of twin fetuses with selective fetal growth restriction / 中华围产医学杂志

Selective fetal growth restriction (sFGR) occurs in about 10% to 15% of monochorionic twins with a high incidence of intrauterine fetal death and low gestational age at birth. sFGR is associated with multisystem adverse prognosis, including brain injury, myocardial hypertrophy, right ventricular outflow tract obstruction, intestinal perforation, and abnormal insulin secretion. sFGR can be classified into three types based on the umbilical artery Doppler waveforms under ultrasound. The clinical characteristics and prognosis vary with the different types. There are few reported studies on the sFGR population, and comprehensive, long-term follow-up is needed.

Asymmetric parasitic twins - Heteropagus

SUMMARY BACKGROUND: Asymmetric or heteropagus conjoined twins is a rare occurrence, with an incidence of one case in 1-2 million. Conjoined twins are classified according to their symmetry, place of fusion, and grade of duplication. METHODS: We report here an extremely rare presentation of parasitic twins not described before. We describe macro and micro anatomic alterations and discuss the aspects of this peculiar presentation and the importance of prenatal diagnosis. RESULTS: The case of a twenty-three-year-old patient, with monochorionic, monoamniotic asymmetrically-conjoined twin pregnancy, discovered at 29 weeks of gestational age. We believe that this report calls attention to this presentation and the importance of prenatal care and management. The twins were delivered vaginally without life. The twins' combined weight was 1.300 gr. They were bonded in the left cervical region. CONCLUSION: This report may help to find strategies for clinical decisions in future cases. Antepartum diagnosis is important to the management, preoperative planning, and outcomes. Prenatal imaging exams like echocardiography, CT, MRI, and ultrasonography are feasible and can provide relevant information about malformation severity and prognosis.

RESUMO BACKGROUND: Gêmeos parasitas assimétricos ou heterópagos são uma ocorrência rara, com incidência de um caso em 1-2 milhões. Os gêmeos siameses são classificados de acordo com sua simetria, local de fusão e grau de duplicação. MÉTODOS: Relatamos aqui uma apresentação extremamente rara de gêmeos parasitários não descritos anteriormente. São descritas alterações macro e microscópicas e discutidos aspectos relevantes dessa malformação e da importância do diagnóstico pré-natal. RESULTADOS: Um caso de uma paciente de 23 anos de idade, com gestação monocoriônica, monoamniótica de gêmeos siameses assimétricos diagnosticada com 29 semanas de idade gestacional. Acreditamos que este relato chama a atenção para esta apresentação e para a importância do cuidado e manejo pré-natal. Os fetos nasceram de parto vaginal já sem vida, pesando em conjunto 1.300 gramas, e eram unidos pela região cervical esquerda. CONCLUSÃO: Este relato pode ajudar a encontrar estratégias para a decisão clínica em casos futuros. O diagnóstico pré-natal é fundamental para o manejo e planejamento pré-operatório. Exames de imagem como ecocardiografia, tomografia computadorizada, ressonância magnética e ultrassonografia são factíveis e podem fornecer informações-chave sobre a gravidade e prognóstico da malformação.

Neurofibromatosis type 2 discordance in monozygous twins.

Neurofibromatosis type 2 (NF2) is an autosomal dominant condition caused by pathogenic variants in the NF2 gene. The pathogenic variant is either inherited or obtained by de novo mutation, characterised by the presence of schwannomas, meningiomas and ependymomas. Here we report the presence of NF2 in one twin, with bilateral vestibular schwannomas and a pathogenic variant of the NF2 gene identified in both tumour and lymphocytes, while his monozygous brother remains asymptomatic. Imaging of the unaffected twin showed no tumour load and genetic testing via Sanger sequencing and Amplification Refractory Mutation System assay demonstrated low levels of expression of the NF2 variant in lymphocytes. Further testing on non-haemopoietic tissue showed little expression or absence of the pathogenic variant. Given there is no family history and the low level of the variant, we assume the pathogenic variant is a de novo mutation during embryogenesis. De novo mutations have been described as occurring at three possible time points in the creation of monozygous twins with different genetic make-up; prior to the twinning event, as a cause of the event, or after the twinning event. Of these options, we hypothesise that the discordance in the expression of the NF2 variant between these twins is likely due to a mutational event that occurred as a result of either of the latter two possibilities, between which we cannot determine. The pathogenic variant in lymphocytes was likely transferred between the twins through a shared blood supply in utero, and the non-haemopoietic samples that showed low levels of expression, were likely due to the presence of lymphocytic cells. Therefore, we have a discordance between monozygous twins at the NF2 gene.

[Analysis of clinical characteristics of discordant structural malformations in one of monochorionic diamnionic twins].

Objective: To analyze the clinical characteristics of structural malformations in one of monochorionic diamnionic twins (MCDA). Methods: The clinical data of 77 MCDA patients with structural malformations diagnosed by ultrasound were retrospectively reviewed from January 2012 to May 2017. The distribution of structural malformations, prenatal chromosomal karyotyping and pregnancy outcomes were analyzed. Results: (1)Among the 77 MCDA patients with structural malformations, the single malformation accounted for 79%(61/77), the multiple malformations accounted for 21%(16/77). And there were a total of 94 types of malformations, the top three malformations were neurological malformations (32%, 30/94), cardiovascular malformations (29%, 27/94) and twin reversed arterial perfusion sequence (TRAPS;10%,9/94).(2)Among the 77 patients with structural malformation, 64 cases (83%, 64/77) were examined for fetal chromosomes, of whom 14 cases (22%,14/64) were examined for fetal chromosomes of both twins, with 1 case (1/14) of discordant fetal chromosome. (3)Among the 77 patients, 4 cases (5%, 4/77) with severe fetal malformations terminated pregnancy. Totally 29 cases (38%,29/77) with severe malformations were treated with selective fetal reduction, among whom 7 cases (24%, 7/29) experienced unexplained fetal death within 24 hours after the operation; 2 cases (7%, 2/29) happened inevitable abortion, and 2 cases (7%, 2/29) underwent unexplained fetal death during the late pregnancy. Of the remaining 44 patients (57%,44/77) with expectant treatment, 13 cases (30%,13/44) occurred twin transfusion syndrome (Ⅱ-Ⅳ), and were treated with fetoscopic laser occlusion. Eight patients had 2 survival twins, 4 patients delivered 1 survival twin, and 1 patient had dead twins. Conclusions: The most common malformations in MCDA twins are the nervous malformations, cardiovascular malformations and TRAPS. The chromosome karyotype of MCDA twins with structural malformations are sometimes discordant, and separate samling of the twins is suggested for prenatal diagnosis. Selective fetal reduction could be given to severe structural malformation in MCDA patients safely and effectively. For non-severe structural malformation in MCDA patients with twin transfusion syndrome, fetoscopic laser occlusion is safe and effective.

Remitted affective disorders and high familial risk of affective disorders associate with aberrant intestinal microbiota.

OBJECTIVE: Affective disorders seem associated with aberrant intestinal microbiota but whether this pattern also occurs in individuals at increased heritable risk is unknown. We investigated associations between gut microbiota profiles and affective disorders by comparing monozygotic (MZ) twins concordant (affected twins with unipolar or bipolar disorder in remission) and discordant to affective disorders (high-risk) with MZ twins without affective disorders (low-risk). METHODS: Stool samples were collected from 128 MZ twins and the microbiome was profiled using 16S rDNA sequencing of the V3-V4 region. RESULTS: Affected twins had a lower diversity and an absence of a specific operational taxonomical unit (OTU) in comparison with low-risk twins. The high-risk twins exhibited the same pattern although the lower diversity was only at a trend level. The OTU belonged to the family Christensenellaceae. The findings were not explained by lifestyle factors (smoking, alcohol consumption, body mass index, or psychotropic medication). CONCLUSION: Affected twins in remission and high-risk twins presented aberrant gut microbiota with depletion of a specific OTU. If replicated, this reduced relative sequence absence may together with the globally altered microbiota composition act as a vulnerability marker by accentuating the effect of gene-environment interactions in individuals genetically disposed for an affective disorder.

Growth follow-up of monochorionic diamniotic twins discordant for birth weight during their first 24 months of life / 中华围产医学杂志

Objective To assess the growth of monochorionic diamniotic (MCDA) twins discordant for birth weight during their first 24 months of life.Methods Clinical data and growth parameters from birth to 24 months of age of 31 pairs(62 cases) of birth weight-discordant MCDA twins (≥ 25％ difference in birth weight) who were born alive in the First Affiliated Hospital,Sun Yat-sen University between January 1,2010 and June 30,2016 were retrospectively analyzed.Each pair of twins was divided into the large birth weight group (31 cases) and the small birth weight group (31 cases).All datas were statistically analyzed with Chisquare test,paired t test,analysis of variance or LSD-t test.Results (1) The incidence of birth defects and hypoproteinemia in the small birth weight group were higher than that in the large birth weight group [29.0％ (9/31) vs 0.0％ (0/31),54.8％ (17/31) vs 25.8％ (8/31);x2=8.319 and 5.429;both P ＜ 0.05].(2) The standard deviation scores (SDS) of weight,length and head circumference at birth and 1,6,12,18 and 24 months of age of the small birth weight group were lower than those of the large birth weight group [birth:(-2.00 ± 0.66) vs (-0.04±0.60),(-1.83±1.13) vs (-0.37±0.83),(-1.42±1.03) vs (0.17±0.84),t=17.214,8.390 and 7.759;1 month:(-1.77±0.81) vs (-0.60±0.65),(-2.36±1.20) vs (-0.94±0.74),(-1.71±1.26) vs (-0.44± 1.09),t=9.424,9.059 and 7.197;6 months (-1.00±0.84) vs (-0.09±0.56),(-1.31 ± 1.22) vs (-0.04±0.80),(0.30±1.51) vs (1.11 ± 1.20),t=-7.578,7.988 and 6.091;12 months:(-0.34±1.06) vs (0.47±0.79),(-1.00±0.92) vs (-0.14±0.73),(-0.16±0.76) vs (0.49±0.58),t=5.747,7.155 and 5.664;18 months:(-0.06±0.95) vs (0.74±0.66),(-0.92± 1.07) vs (-0.24±0.92),(-0.32±0.72) vs (0.29±0.66),t=6.153,4.496 and 3.877;24 months:(0.20±0.79) vs (0.88±0.62),(-0.66±0.59) vs (0.01 ±0.67),(-0.37±0.60) vs (0.34±0.68),t=5.317,4.800 and 4.905;all P ＜ 0.001].However,the changes in SDS (△ SDS) of weight,length and head circumference from birth to 24 months of age and the incidence of △ SDS ＞ 0.67 were significantly higher in the small birth weight group than those in the large birth weight group [△SDS:(2.20± 1.10) vs (0.92±0.91),(1.17± 1.21) vs (0.37± 1.14),(1.05± 1.07) vs (0.16±0.89),t=8.422,3.918 and 3.547,all P ＜ 0.001;△SDS ＞ 0.67:93.5％ (29/31) vs 61.3％ (19/31),61.3％ (19/31) vs 35.5％ (11/31),61.3％ (19/31) vs 29.0％ (9/31),x2=9.226,4.133 and 6.53 1,all P ＜ 0.05].(3) The difference in SDS for weight,length and head circumference between the large and small birth weight twins at 24 months of age were significantly lower than those at birth [(0.68 ± 0.71) vs (1.95 ± 0.63),(0.67 ± 0.77) vs (1.46± 0.97),(0.71 ± 0.80) vs (1.60±1.15);all P ＜ 0.05].Conclusions Growth differences are found between birth weight-discordant MCDA twins all the way to 24 months of age from birth at a reduced trend.

Monochorionic monoamniotic twins discordant for anencephaly: a case report / 中华围产医学杂志

We reported a case of monochorionic monoamniotic twins discordant for anencephaly diagnosed by second-trimester ultrasonography at the First Affiliated Hospital of Fujian Medical University.Ultrasound at seven weeks of gestation showed only one gestational sac with an embryo inside.Another 12 gestational weeks' ultrasound scan performed at another hospital found one gestational sac and one fetus (crown-rump length was 6.11 cm and nuchal translucency was 0.11 cm) in the upper-middle uterine cavity.The ultrasound examination at 22+6 gestational weeks identified one placenta and two fetuses without obvious diaphragm echo in between.Although no structural abnormality was observed in one fetus,frog-like eyes,absence of skull image and brain tissue echo were presented in the other fetus.The patient was transferred to a higher level hospital and was successfully performed radiofrequency ablation for selective reduction at 23+4 weeks of gestation.At 35 weeks,a premature live boy and an anencephalic stillbirth fetus were born vaginally after premature rupture of membranes.The baby boy was healthy at follow-up at four months old.

Predictive value of first-trimester ultrasound markers for complicated monochorionic diamniotic twins / 中华围产医学杂志

Objective@#To investigate the value of first-trimester ultrasound parameters in predicting complicated monochorionic diamniotic (MCDA) twins.@*Methods@#In this retrospective study, pregnant women diagnosed as MCDA twins by ultrasound in the First Affiliated Hospital of Sun Yat-sen University from January 2013 to January 2018 were recruited and divided into the following four groups: non-complicated MCDA twins group, twin-twin transfusion syndrome (TTTS) group, selective intrauterine growth restriction (sIUGR) group and twin anemia-polycythemia sequence (TAPS) group. Thickness of nuchal translucency (NT), crown-rump length (CRL), umbilical cord insertion (UCI) and ductus venosus (DV) flow at 11-14 weeks of gestation were recorded. The predictive value for complicated MCDA twins was analyzed using t-test, Chi-square (or Fisher's exact) test, multivariate logistic regression analysis and receiver operating characteristic (ROC) curve.@*Results@#(1) A total of 430 MCDA twin pregnancies were included in this study with 152 in the TTTS group, 142 in the sIUGR group, seven in the TAPS group and 129 in the normal MCDA twins group. No further analysis was performed on the TAPS group due to the small sample size. (2) NT discordance in twins of the TTTS group was significantly greater than that in the normal MCDA twins group[(21.5±16.0)% vs (14.6±13.5)%, t=-3.533, P<0.001]. The area under ROC curve (AUC) of TTTS predicted by NT discordance was 0.649. Stratified analysis showed that TTTS was best predicted when NT discordance was 20% with the sensitivity of 57.9% and specificity of 70.6%. (3) The sIUGR group had greater discordance in CRL and NT and higher UCI discordance than the normal MCDA twins group [NT: (27.8±21.3)% vs (14.6±13.5)%, t=-5.556, P<0.001; CRL: (8.6±6.9)% vs (5.4±4.4)%, t=-3.144, P=0.002; UCI: 47.9% (68/142) vs 13.9% (18/129), χ2=35.929, P<0.001]. The AUC of sIUGR was 0.675 predicted by NT discordance and 0.649 by CRL discordance. Stratified analysis showed that NT discordance of 20% and CRL discordance of 10% were the best prediction for sIUGR with the sensitivity of 53.1% and 34.7% and specificity of 72.1% and 83.8%, respectively. Multivariate logistic regression analysis suggested that UCI discordance was the risk factor for sIUGR (OR=7.165, 95%CI: 2.637-19.472).@*Conclusions@#MCDA twins with NT discordance greater than 20% during early pregnancy are at increased risk for TTTS. CRL discordance greater than 10%, NT discordance greater than 20% and abnormal UCI are risk factors for sIUGR.

Predictive value of first-trimester ultrasound markers for complicated monochorionic diamniotic twins / 中华围产医学杂志

Objective To investigate the value of first-trimester ultrasound parameters in predicting complicated monochorionic diamniotic (MCDA) twins. Methods In this retrospective study, pregnant women diagnosed as MCDA twins by ultrasound in the First Affiliated Hospital of Sun Yat-sen University from January 2013 to January 2018 were recruited and divided into the following four groups: non-complicated MCDA twins group, twin-twin transfusion syndrome (TTTS) group, selective intrauterine growth restriction (sIUGR) group and twin anemia-polycythemia sequence (TAPS) group. Thickness of nuchal translucency (NT), crown-rump length (CRL), umbilical cord insertion (UCI) and ductus venosus (DV) flow at 11-14 weeks of gestation were recorded. The predictive value for complicated MCDA twins was analyzed using t-test, Chi-square (or Fisher's exact) test, multivariate logistic regression analysis and receiver operating characteristic (ROC) curve. Results (1) A total of 430 MCDA twin pregnancies were included in this study with 152 in the TTTS group, 142 in the sIUGR group, seven in the TAPS group and 129 in the normal MCDA twins group. No further analysis was performed on the TAPS group due to the small sample size. (2) NT discordance in twins of the TTTS group was significantly greater than that in the normal MCDA twins group[(21.5±16.0)% vs (14.6±13.5)%, t=－3.533, P<0.001]. The area under ROC curve (AUC) of TTTS predicted by NT discordance was 0.649. Stratified analysis showed that TTTS was best predicted when NT discordance was 20% with the sensitivity of 57.9% and specificity of 70.6%. (3) The sIUGR group had greater discordance in CRL and NT and higher UCI discordance than the normal MCDA twins group [NT: (27.8±21.3)% vs (14.6±13.5)%, t=－5.556, P<0.001; CRL: (8.6±6.9)% vs (5.4±4.4)%, t=－3.144, P=0.002; UCI: 47.9% (68/142) vs 13.9% (18/129), χ2=35.929, P<0.001]. The AUC of sIUGR was 0.675 predicted by NT discordance and 0.649 by CRL discordance. Stratified analysis showed that NT discordance of 20% and CRL discordance of 10% were the best prediction for sIUGR with the sensitivity of 53.1% and 34.7% and specificity of 72.1% and 83.8%, respectively. Multivariate logistic regression analysis suggested that UCI discordance was the risk factor for sIUGR ( OR=7.165, 95% CI : 2.637-19.472). Conclusions MCDA twins with NT discordance greater than 20% during early pregnancy are at increased risk for TTTS. CRL discordance greater than 10%, NT discordance greater than 20% and abnormal UCI are risk factors for sIUGR.

Cerebellar Asymmetry and Cortical Connectivity in Monozygotic Twins with Discordant Handedness.

Handedness differentiates patterns of neural asymmetry and interhemispheric connectivity in cortical systems that underpin manual and language functions. Contemporary models of cerebellar function incorporate complex motor behaviour and higher-order cognition, expanding upon earlier, traditional associations between the cerebellum and motor control. Structural MRI defined cerebellar volume asymmetries and correlations with corpus callosum (CC) size were compared in 19 pairs of adult female monozygotic twins strongly discordant for handedness (MZHd). Volume and asymmetry of cerebellar lobules were obtained using automated parcellation.CC area and regional widths were obtained from midsagittal planimetric measurements. Within the cerebellum and CC, neurofunctional distinctions were drawn between motor and higher-order cognitive systems. Relationships amongst regional cerebellar asymmetry and cortical connectivity (as indicated by CC widths) were investigated. Interactions between hemisphere and handedness in the anterior cerebellum were due to a larger right-greater-than-left hemispheric asymmetry in right-handed (RH) compared to left-handed (LH) twins. In LH twins only, anterior cerebellar lobule volumes (IV, V) for motor control were associated with CC size, particularly in callosal regions associated with motor cortex connectivity. Superior posterior cerebellar lobule volumes (VI, Crus I, Crus II, VIIb) showed no correlation with CC size in either handedness group. These novel results reflected distinct patterns of cerebellar-cortical relationships delineated by specific CC regions and an anterior-posterior cerebellar topographical mapping. Hence, anterior cerebellar asymmetry may contribute to the greater degree of bilateral cortical organisation of frontal motor function in LH individuals.

PALMARIS LONGUS ABSENT IN ONE IDENTICAL TWIN: A CASE REPORT.

- Palmaris longus is a very variable muscle in the human body, but it is often used as an applicable tendon graft. We report on differences between one pair of identical twins regarding the existence of the palmaris longus, which were detected accidentally during examination of the presence/absence of this muscle in Caucasian population. In one of the twins, the palmaris longus was present at both forearms, while the other twin was lacking this muscle at both forearms. On search of the available literature, we found no articles about distinctions in the presence or absence of the palmaris longus in twins.

[Research Progress on the Detection Method of DNA Methylation and Its Application in Forensic Science].

As an important part of epigenetic marker, DNA methylation involves in the gene regulation and attracts a wide spread attention in biological auxology, geratology and oncology fields. In forensic science, because of the relative stable, heritable, abundant, and age-related characteristics, DNA methylation is considered to be a useful complement to the classic genetic markers for age-prediction, tissue-identification, and monozygotic twins' discrimination. Various methods for DNA methylation detection have been validated based on methylation sensitive restriction endonuclease, bisulfite modification and methylation-CpG binding protein. In recent years, it is reported that the third generation sequencing method can be used to detect DNA methylation. This paper aims to make a review on the detection method of DNA methylation and its applications in forensic science.

Single Fetal Death in Monochorionic Twin Pregnancy: Co-Twin Prognosis and Neonatal Outcome.

The incidence of single fetal death in twin pregnancy varies from 0.5% - 6.8%, leaving the surviving fetus with increased morbi-mortality. The prognosis is worse in monochorionic pregnancies. In addressing these cases it should be noted referral to tertiary center with differentiated perinatal support, induction of fetal lung maturation and termination of pregnancy if there's loss of fetal well-being or possibility of maternal complications and suspected neurological sequelae in the surviving fetus. The risk of iatrogenic prematurity should always be weighed with the possible consequences arising from the fetus staying in a hostile uterine environment. The authors describe a case of a 32-year-old pregnant woman with monochorionic/diamniotic twin pregnancy diagnosed with death of one of the fetuses due to fetal growth restriction and velamentous insertion of the umbilical cord at 30 weeks of gestation. The couple opted for termination of pregnancy at 33 weeks after documentation of brain changes in the surviving fetus.

A incidência de morte fetal de um feto na gestação gemelar varia de 0,5% - 6,8%, deixando o feto sobrevivente com morbi-mortalidade aumentada. O prognóstico é pior em gestações monocoriónicas. Ao abordar estes casos importa realçar a referenciação a centro terciário com apoio perinatal diferenciado, a indução da maturação pulmonar fetal e a interrupção da gravidez se houver perda de bem-estar fetal ou possibilidade de complicações maternas ou suspeita de sequelas neurológicas no feto sobrevivente, devendo os riscos da prematuridade iatrogénica serem sempre pesados com as possíveis sequelas decorrentes da permanência do feto num ambiente uterino hostil. Os autores descrevem o caso de uma mulher de 32 anos com gravidez monocoriónica/diamniótica com morte de um dos fetos, com restrição de crescimento grave e inserção velamentosa do cordão umbilical, pelas 30 semanas de gestação. O casal optou pela terminação da gravidez às 33 semanas, após documentação de alterações cerebrais no feto sobrevivente.