Congenital cytomegalovirus infection among twin pairs

Objective: The purpose of this study was to describe the fetal/neonatal cytomegalovirus (CMV) status according to chorionicity and outcome in twin pregnancies diagnosed with CMV.

Methods: An opportunistic diagnosis of CMV infection was performed in a tertiary referral center. All cases diagnosed in twin pregnancies (2006–2011) were included. Prenatal diagnosis was performed by CMV-DNA in the amniotic fluid (AF) of both fetuses only on the evidence of sonographic findings in either one or both twins. Neonatal screening was selectively assessed in symptomatic newborns, preterm, and infants born to HIV-infected mothers. Congenital infection was considered in the presence of CMV-DNA in AF, fetal tissues or newborn urine within the first 2 weeks of life, and symptomatic disease with clinical findings at birth or autopsy.

Results: A total of six twin pregnancies with congenital CMV infection were diagnosed, five dichorionic and one monochorionic diamniotic. Only one sibling was infected among dichorionic pregnancies, two diagnosed prenatally, and three after birth. In the monochorionic pregnancy, the diagnosis was performed prenatally and the two fetuses were infected and severely damaged.

Conclusions: Congenital CMV infection in twins might be related, among other factors, to chorionicity, and in DC twins a non-concordant infection can be expected.     

Factors determining early pregnancy loss in singleton and multiple implantations

BACKGROUND: The incidence of first trimester pregnancy loss is much lower in IVF twin pregnancies than in IVF singleton pregnancies. The objective of this study was to determine which embryonic and maternal factors contribute to this finding. METHODS: Retrospective data analysis of the outcome of 1593 pregnancies after day 3 double-embryo transfer (DET) after IVF or ICSI treatment. RESULTS: Of 1148 single implantations at 6 weeks, 936 (81.5%) were ongoing pregnancies. Of 445 multiple implantations at 6 weeks, 354 (79.6%) were ongoing multiple pregnancies, 80 (17.9%) were ongoing singleton pregnancies and 11 (2.5%) ended in a spontaneous abortion. Total pregnancy loss was 18.5 and 2.5% (P < 0.001) in singleton and twin gestations, respectively. Loss per gestational sac was 18.5 and 11.46% (P < 0.001), respectively. Determinants contributing to the continuation of gestation beyond 6 weeks were young maternal age, possibility to cryopreserve embryos and short GnRH agonist flare-up stimulation protocol. Whereas factors promoting multiple implantation at 6 weeks of gestation were young maternal age, high cumulative embryo score (CES), male infertility, long stimulation protocol and thick endometrium. CONCLUSIONS: Although multiple implantation at 6 weeks is predominantly determined by (morphological) embryo quality, the continuation of pregnancy beyond 6 weeks becomes more dependent on the combination of genetic and developmental potential of the embryo(s) and an optimal uterine milieu.     

多普勒超声对双胎输血综合征外周血流变化的研究

双胎输血综合征（ＴＴＴＳ）近年来已越来越引起妇产科临床的关注。本文应用多普勒超声对１１例ＴＴＴＳ胎儿的外周血流进行评价，以探讨两胎儿间不同的血流动力学形式及对妊娠后期危险性预测，结果：１、供、受血儿脐动脉搏动指数（ＰＩ）值明显高于正常组（Ｐ＜０．０１）；２、外周动脉－降主动脉（ＤＡＯ）及大脑中动脉（ＭＣＡ）ＰＩ值和峰值（Ｖｍ）降低（Ｐ＜０．０１）；３、妊娠晚期受血儿充血性心衰加重时脐静脉出现搏动性血流及心内房室瓣返流，结论：外周血流多普勒频谱改变为ＴＴＴＳ的诊断和治疗提供了准确的资料，ＴＴＴＳ胎儿的多普勒超声监测有助于降低围产期死亡率     

Bayesian Latent Variable Collapsing Model for Detecting Rare Variant Interaction Effect in Twin Study

By analyzing more next‐generation sequencing data, researchers have affirmed that rare genetic variants are widespread among populations and likely play an important role in complex phenotypes. Recently, a handful of statistical models have been developed to analyze rare variant (RV) association in different study designs. However, due to the scarce occurrence of minor alleles in data, appropriate statistical methods for detecting RV interaction effects are still difficult to develop. We propose a hierarchical Bayesian latent variable collapsing method (BLVCM), which circumvents the obstacles by parameterizing the signals of RVs with latent variables in a Bayesian framework and is parameterized for twin data. The BLVCM can tackle nonassociated variants, allow both protective and deleterious effects, capture SNP‐SNP synergistic effect, provide estimates for the gene level and individual SNP contributions, and can be applied to both independent and various twin designs. We assessed the statistical properties of the BLVCM using simulated data, and found that it achieved better performance in terms of power for interaction effect detection compared to the Granvil and the SKAT. As proof of practical application, the BLVCM was then applied to a twin study analysis of more than 20,000 gene regions to identify significant RVs associated with low‐density lipoprotein cholesterol level. The results show that some of the findings are consistent with previous studies, and we identified some novel gene regions with significant SNP–SNP synergistic effects.     

Type of delivery and reading,writing, and arithmetic learning in twin births

This study analyses, in children born in twin births, the relationship between reading, writing and arithmetic learning, on the one hand, and type of delivery, on the other, controlling for the effect of interaction and/or confusion of third variables (maternal age at delivery, gestational age, fetal position, birthweight, 1-min Apgar score). In the planned retrospective cohort design, the exposed cohort consisted of children born by caesarean section, and the non-exposed cohort was comprised of children born vaginally. One hundred and twenty-four children born of twin births were evaluated during their first year of primary school: K-BIT tests were used to measure intelligence; the Evalúa-1 battery was used to assess reading, writing, and arithmetic ability; and the children's clinical histories were analysed for obstetric and neonatal variables. After applying binary logistic regressions for each dependent variable, it was found that caesarean delivery in twin births appeared as a possible independent risk factor for specific learning disabilities (LDs) in reading, writing, and arithmetic. Based on these results, further research using larger samples and at more advanced ages is required in order to analyse the influence of obstetric and neonatal variables on the processes underlying specific LDs.