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Objectives This study aimed to assess the applicability of the National Academy of Medicine (NAM) interim guidelines for twin pregnancies to the specific population of gestational diabetes mellitus by exploring the relationship between gestational weight gain and adverse pregnancy outcomes in Chinese twin-pregnant women with gestational diabetes mellitus. Study Design This was a retrospective cohort study of women diagnosed with diabetes in pregnancy between July 2017 and December 2020 at the Maternal and Child Health Hospital in Chongqing, China. The primary variable of interest was maternal total gestational weight gain. The primary outcomes were perinatal outcomes, which included: preeclampsia, small for gestational age, large for gestational age, low birth weight, neonatal pneumonia, neonatal respiratory distress syndrome, and neonatal intensive unit admission, etc. The association between inappropriate gestational weight gain and adverse pregnancy outcomes was estimated using multiple logistic regression analysis. Results A total of 455 twin-pregnant women who had gestational diabetes mellitus were analyzed. Women with low gestational weight gain had reduced risk of preeclampsia (adjusted odds ratio [aOR], 0.32; 95% CI or confidence interval, 0.17–0.63; p = 0.001) and their infants had higher risks of small for gestational age (aOR, 1.93; 95% CI, 1.04–3.58; p = 0.037), low birth weight (aOR, 2.27; 95% CI, 1.32–3.90; p = 0.003), neonatal intensive unit admission (aOR, 3.29; 95% CI, 1.10–5.78; p = 0.038), pneumonia (aOR, 2.41; 95% CI, 1.08–5.33; p = 0.031), and neonatal respiratory distress syndrome (aOR, 2.29; 95% CI, 1.10–4.78; p = 0.027); the infants of women with excessive gestational weight gain had a higher risk of large for gestational age (aOR, 3.76; 95% CI, 1.42–9.96; p = 0.008). Conclusion Gestational weight gain controlled within the range recommended by the NAM could reduce the risk of perinatal adverse outcomes. The 2009 NAM gestational weight gain recommendations can be used for Chinese twin-pregnant women with gestational diabetes mellitus. Key Points Inappropriate gestational weight gain can lead to adverse perinatal outcomes in twin pregnancies. Gestational weight gain controlled within recommended range could reduce the risk of poor perinatal outcomes. The National Academy of Medicine recommendations are suitable for Chinese twin-pregnant women with GDM. [ABSTRACT FROM AUTHOR]

Yanshan cashmere goats are an excellent local breed in China. They produce one kid per litter, however, a few female goats produce twins. To gain more insight into this phenomenon, (Method) we analyzed the ovarian tissues of does with single birth (SB) and 3 twin births (TB). To understand the genes responsible for singleton and twin production, ovarian tissues from SB and TB Yanshan cashmere goats were obtained during the estrous period and subjected to histological and transcriptomics analyses. (Results) We identified 306 differentially expressed genes (DEGs) between the TB and SB groups. KEGG analysis revealed pathways revealed that the identified DEGs were involved in 11 reproductive signaling pathways. Finally, gene ontology and protein-protein interaction analysis revealed nine DGEs associated with reproductive performance. ADAMTS16 expression was significantly higher in the ovary and uterus than in other organs. Moreover, ADAMTS16 expression was significantly higher in the TB group than in the SB group, suggesting its association with the twin trait in Yanshan cashmere goats. (Conclusion) Our findings enrich our understanding of the molecular mechanisms of high fecundity. They offer insights into increasing the number of kids per litter, and thereby, the development of the cashmere industry. [ABSTRACT FROM AUTHOR]

Objective: To compare the maternal and neonatal outcomes of twin pregnancies between vertex and nonvertex presentations of the second twin in vaginal delivery. Methods: In this unicentric retrospective cohort study, we collected data from 213 cases of vaginal twin deliveries from January 2016 to July 2020. Participants were divided into the vertex‐vertex presentation group (VV) and vertex‐breech presentation group (VB). Data on maternal and neonatal outcomes were compared between groups. Results: Among the 213 mothers and 426 infants (213 twin pairs), there were 140 women in the VV group and 73 women in the VB group (65.73% vs. 34.27%). Infants in the VB group had a higher incidence of admission to NICU (51.43% vs. 68.49%, p = 0.017), lower 1‐min (11.43% vs. 28.77%, p < 0.001) and 5‐minute Apgar scores (1.43% vs. 4.11%, p = 0.043) for the second twin. However, after the adjustment for sex of the twin, birth weight, chorionicity, and gestational age, the greater risk of admission to NICU and low 5‐min Apgar score was no longer significantly different. Conclusion: VB twins are at no greater overall risk of a poor outcome due to breech presentation in the second twin. However, the presentation of the second fetus represents a risk factor for a low 1‐min Apgar score. Obstetricians and midwives should consider appropriate interventions for second twins who present breech versus vertex. [ABSTRACT FROM AUTHOR]

We estimate the causal effect of income on happiness using a unique dataset of Chinese twins. This allows us to address omitted variable bias and measurement errors. Our findings show that individual income has a large positive effect on happiness, with a doubling of income resulting in an increase of 0.26 scales or 0.37 SDs in the four-scale happiness measure. We also find that income matters most for males and the middle-aged. Our results highlight the importance of accounting for various biases when studying the relationship between socioeconomic status and subjective well-being. [ABSTRACT FROM AUTHOR]

Background: The prevalence of preterm birth has been rising, and there is a paucity of nationwide data on the perinatal characteristics and neonatal outcomes of twin deliveries of very preterm infants (VPIs) in China. This study compared the perinatal characteristics and outcomes of singletons and twins admitted to neonatal intensive care units (NICUs) in China. Methods: The study population comprised all infants born before 32 weeks in the Chinese Neonatal Network (CHNN) between January 2019 and December 2019. Three-level and population-average generalized estimating equation (GEE)/alternating logistic regression (ALR) models were used to determine the association of twins with neonatal morbidities and the use of NICU resources. Results: During the study period, there were 6634 (71.2%) singletons and 2680 (28.8%) twins, with mean birth weights of 1333.70 g and 1294.63 g, respectively. Twins were significantly more likely to be delivered by caesarean section (p < 0.01), have antenatal steroid usage (p = 0.048), have been conceived by assisted reproductive technology (ART) (p < 0.01), have a higher prevalence of maternal diabetes (p < 0.01) and be inborn (p < 0.01) than singletons. In addition, twins had a lower prevalence of small for gestational age, maternal hypertension, and primigravida mothers than singletons (all p < 0.01). After adjusting for potential confounders, twins had higher mortality rates (adjusted odds ratio [AOR] 1.28, 95% confidence interval [CI] 1.10–1.49), higher incidences of short-term composite outcomes (AOR 1.28, 95% CI 1.09–1.50), respiratory distress syndrome (RDS) (AOR 1.30, 95% CI 1.12–1.50), and bronchopulmonary dysplasia (BPD) (AOR 1.10, 95% CI 1.01–1.21), more surfactant usage (AOR 1.22, 95% CI 1.05–1.41) and prolonged hospital stays (adjusted mean ratio 1.03, 95% CI 1.00–1.06), compared to singletons. Conclusion: Our work suggests that twins have a greater risk of mortality, a higher incidence of RDS and BPD, more surfactant usage, and longer NICU stays than singletons among VPIs in China. [ABSTRACT FROM AUTHOR]

An abnormal alanine aminotransferase (ALT) level is predictive of disease and all-cause mortality and may indicate liver injury. Using twin modeling, the genetic and environmental factors that affect human serum ALT levels have been well studied for the populations in the different countries, and the results showed moderate-to-high heritability. However, the heritability of ALT level has not been explored in Chinese population. Thus, we recruited 369 pairs of twins (233 monozygotic and 136 dizygotic) from the Qingdao Twin Registry in China with a median age of 50 years (40−80 years). Correlation analysis and a structural equation model (SEM) were conducted to evaluate the heritability of ALT level. The data for age, gender, body mass index and alcohol consumption were set as covariates. Intrapair correlation in monozygotic twins was 0.64 (95%CI [.56,.71]) and 0.42 (95% CI [.28,.55]) in dizygotic twins. The SEM analysis indicated that 65% (95% CI [57%, 71%]) of the variation in ALT levels can be explained by additive genetics and 35% (95% CI [29%, 44%]) of the variation is attributed to unique environmental factors or residuals. Shared environmental influences were not significant. In conclusion, serum ALT variations exhibited strong genetic effects. The variation could also be explained by unique environmental factors. However, shared environmental factors have a minor impact on the serum ALT level. [ABSTRACT FROM AUTHOR]

Consequences of prenatal maternal depressive symptoms on infant health are well established. But the results of infants' sex differences of such consequences are mixed. The current study examines whether any association exists between prenatal maternal depressive symptoms and infant physical health different for the sex of newborns. A sample of 84 women pregnant with twins reported depressive symptoms using the Edinburgh Postnatal Depression Scale (EPDS) in the late gestational stage. The Apgar scores of newborns were assessed by healthcare providers at 1, 5, and 10 minutes after birth. The relationship of maternal prenatal depressive symptoms and newborns' physical health was moderated by infant sex. Higher depressive symptoms were associated with a lower Apgar index among newborn boys but not girls. Fetus environment or biomarkers related to sex may be a key mechanism of the effect of prenatal depression symptoms on newborns' health. Tailored interventions targeting maternal depression symptoms may be warranted. [ABSTRACT FROM AUTHOR]

Background: With the development of assisted reproductive technology, the twinning rate in China has been increasing. However, little is known about twinning from 2014 onwards. In addition, previous studies analysing optimal gestational times have rarely considered maternal health conditions. Therefore, whether maternal health conditions affect the optimal gestational time remains unclear.Methods: Data of women delivered between January 2012 and December 2020 were collected through China's National Maternal Near Miss Surveillance System. Interrupted time series analysis was used to determine the rates of twinning, stillbirth, smaller than gestational age (SGA), and low Apgar scores (< 4) among twins in China. To estimate the risk of each adverse perinatal outcome for separate gestational weeks, a multivariate generalised linear model was used. Infants born at 37 weeks of gestational age or foetuses staying in utero were used as reference separately. The analyses were adjusted for the sampling distribution of the population and the cluster effect at the hospital and individual levels were considered.Results: There were 442,268 infants enrolled in this study, and the adjusted rates for twinning, stillbirth, SGA, and low Apgar scores were 3.10%, 1.75%, 7.70%, and 0.79%, respectively. From 2012 to 2020, the twinning rate showed an increasing trend. Adverse perinatal outcomes, including stillbirth, SGA, and low Apgar scores showed a decreasing trend. A gestational age between 34 and 36 weeks decreased most for rate of stillbirth (average changing rate -9.72%, 95% confidence interval [CI] -11.41% to -8.00%); and a gestational age of between 37 and 38 weeks decreased most for rates of SGA (average changing rate -4.64%, 95% CI -5.42% to -3.85%) and low Apgar scores (average changing rate -17.61%, 95% CI -21.73% to -13.26%). No significant difference in changes in twinning rate or changes of each perinatal outcome was observed during periods of different fertility policies. Infants born at 37 weeks of gestation had a decreased risk of stillbirth, SGA, and low Apgar scores. Maternal antepartum or medical complications increased the risk of SGA and low Apgar scores in different gestational weeks.Conclusion: China's twinning rate showed an increasing trend, while adverse perinatal outcomes decreased from 2012 to 2020. Fertility policy changes have had little effect on the twinning rate or the rate of adverse perinatal outcomes such as stillbirth, SGA, or low Apgar scores. The optimal gestational age for twins was 37 weeks. Women pregnant with twins and with antepartum or medical complications should be cautious due to an increased risk of SGA and low Apgar scores. [ABSTRACT FROM AUTHOR]

The military victories of the Northern Expedition (1926–28) ended nearly two decades of political fragmentation and ushered in a new era of centralized government in China. A key concern of the Nationalist government, based in Nanjing, was bringing the haphazard array of private schools that had emerged since the republic's founding in 1911 in line with the Nationalists' political agenda. The Nationalist leadership also hoped to use their educational reforms to bring the frontier regions, many of which were only tenuously allied with Nanjing, more formally under their control. Thus, the new regime set out to achieve the twin goals of regulating private schools and cultivating ties among the frontier region's population. These two goals became entangled in an unexpected manner at the private Muslim Chengda Teachers School. Although the Nationalists banned private teachers schools in 1933, they deliberately exempted Chengda from such regulations to further their frontier agenda. Later, when the central government's frontier political calculations changed, the Nationalists rescinded such protection and forced Chengda to abide by the original regulations. [ABSTRACT FROM AUTHOR]

The aims of this study are to estimate the contributions of genetic factors to the variation of tea drinking and cigarette smoking, to examine the roles of genetic factors in their correlation and further to investigate underlying causation between them. We included 11 625 male twin pairs from the Chinese National Twin Registry (CNTR). Bivariate genetic modelling was fitted to explore the genetic influences on tea drinking, cigarette smoking and their correlation. Inference about Causation through Examination of FAmiliaL CONfounding (ICE FALCON) was further used to explore the causal relationship between them. We found that genetic factors explained 17% and 23% of the variation in tea drinking and cigarette smoking, respectively. A low phenotypic association between them was reported (rph  = 0.21, 95% confidence interval [CI]: [0.19, 0.24]), which was partly attributed to common genetic factors (rA  = 0.45, 95% CI [0.19, 1.00]). In the ICE FALCON analysis with current smoking as the exposure, tea drinking was associated with his own (βself = 0.39, 95% CI [0.23, 0.55]) and his co-twin's smoking status (βco-twin = 0.25, 95% CI [0.10, 0.41]). Their association attenuated with borderline significance conditioning on his own smoking status (p = 0.045), indicating a suggestive causal effect of smoking status on tea drinking. On the contrary, when we used tea drinking as the predictor, we found familial confounding between them only. In conclusion, both tea drinking and cigarette smoking were influenced by genetic factors, and their correlation was partly explained by common genetic factors. In addition, our finding suggests that familial confounders account for the relationship between tea drinking and cigarette smoking. And current smoking might have a causal effect on weekly tea drinking, but not vice versa. [ABSTRACT FROM AUTHOR]

Introduction: Our study compared the prospective risks of intrauterine fetal death (IUFD), neonatal death (NND), perinatal death (PND), and neonatal morbidities in monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA) twin pregnancies. Methods: This retrospective cohort study included twin pregnancies who had antenatal care and delivery in a public hospital from 2011 to 2018. Exclusion criteria included monoamnionicity, one/both twin miscarriage, twin‐twin transfusion syndrome, or lethal congenital abnormalities. All twins were managed in multiple pregnancy clinic with standardized protocols. Gestational age‐specific IUFD, NND, PND, and neonatal morbidity rates were compared according to chorionicity. Results: Three hundred seventy‐eight MCDA and 1282 DCDA twins were included. MCDA twins had higher risks of PND (1.9% vs. 0.7% in DCDA twins, p = 0.05), composite neonatal morbidity (p = 0.01), preterm delivery (p < 0.01), and low birth weight (p < 0.01). The prospective risk of IUFD was 0.6% and 0.4% for MCDA and DCDA twins, respectively after 34 weeks' gestation. No NND occurred among deliveries after 30 weeks. The risk of neonatal morbidity of MCDA twins fell from 22.7% at 34 weeks to 2.7% at 37 weeks (p < 0.01). For DCDA twins, the risk of morbidity fell insignificantly from 36 to 38 weeks (4.0% vs. 3.4%, p = 0.60). Logistic regression analysis suggested that the increased risk of perinatal morbidities was related to the higher rate of preterm delivery in MCDA twins rather than chorionicity. Conclusion: With close fetal monitoring, the risk of late IUFD in twin pregnancies without major complications is low. Perinatal morbidity can be minimized by avoiding late preterm deliveries in twin pregnancies. [ABSTRACT FROM AUTHOR]

The aim of the present study was to compare the rate of preterm birth (PTB) and growth from birth to 18 years between twins conceived by in vitro fertilization (IVF) and twins conceived by spontaneous conception (SC) in mainland China. The retrospective cohort study included 1164 twins resulting from IVF and 25,654 twins conceived spontaneously, of which 494 from IVF and 6338 from SC were opposite-sex twins. PTB and low birth weight (LBW), and growth, including length/height and weight, were compared between the two groups at five stages: infancy (0 year), toddler period (1-2 years), preschool (3-5 years), primary or elementary school (6-11 years), and adolescence (10-18 years). Few statistically significant differences were found for LBW and growth between the two groups after adjusting for PTB and other confounders. Twins born by IVF faced an increased risk of PTB compared with those born by SC (adjusted odds ratio [aOR] 8.21, 95% confidence interval [CI] [3.19, 21.13], p < .001 in all twins and aOR 10.12, 95% CI [2.32, 44.04], p = .002 in opposite-sex twins). Twins born by IVF experienced a similar growth at five stages (0-18 years old) when compared with those born by SC. PTB risk, however, is significantly higher for twins conceived by IVF than those conceived by SC. [ABSTRACT FROM AUTHOR]

Background. Age-related hearing impairment (ARHI) is considered an unpreventable disorder. We aimed to detect specific genetic variants that are potentially related to ARHI via genome-wide association study (GWAS). Methods. A sample of 131 dizygotic twins was genotyped for single-nucleotide polymorphism- (SNP-) based GWAS. Gene-based test was performed using VEGAS2. Pathway enrichment analysis was conducted by PASCAL. Results. The twins are with a median age of 49 years, of which 128 were females and 134 were males. rs6633657 was the only SNP that reached the genome-wide significance level for better ear hearing level (BEHL) at 2.0 kHz (P = 1.19 × 10 − 8 ). Totally, 9, 10, 42, 7, 17, and 5 SNPs were suggestive evidence level for (P < 1 × 10 − 5 ) BEHLs at 0.5, 1.0, 2.0, 4.0, and 8.0 kHz and pure tone average (PTA), respectively. Several promising genetic regions in chromosomes (near the C20orf196, AQPEP, UBQLN3, OR51B5, OR51I2, OR52D1, GLTP, GIT2, and PARK2) nominally associated with ARHI were identified. Gene-based analysis revealed 165, 173, 77, 178, 170, and 145 genes nominally associated with BEHLs at 0.5, 1.0, 2.0, 4.0, and 8.0 kHz and PTA, respectively (P < 0.05). For BEHLs at 0.5, 1.0, and 2.0 kHz, the main enriched pathways were phosphatidylinositol signaling system, regulation of ornithine decarboxylase, eukaryotic translation initiation factor (EIF) pathway, amine compound solute carrier (SLC) transporters, synthesis of phosphoinositides (PIPS) at the plasma membrane, and phosphatidylinositols (PI) metabolism. Conclusions. The genetic variations reported herein are significantly involved in functional genes and regulatory domains that mediate ARHI pathogenesis. These findings provide clues for the further unraveling of the molecular physiology of hearing functions and identifying novel diagnostic biomarkers and therapeutic targets of ARHI. [ABSTRACT FROM AUTHOR]

The objective of this study was to analyze differences in birth weight and overweight/obesity in a Shanghai twin cohort. We also wanted to study their association and explore possible risk factors for the discordance of overweight/obesity within twins. This was an internal case-control study designed for twins. The 2012 Shanghai Twin Registration System baseline survey data of a total of 3417 twin pairs were statistically analyzed using SPSS22 software. Results show that the body mass index (BMI) of the Shanghai twin population increased with age. Twins with a high birth weight had a higher BMI and a higher rate of overweight and obesity; 0- to 6-year-old twins, male twins and dizygotic (DZ) twins had higher rates of overweight/obesity than other groups. The greater the discordant birth weight rate of twins, the more obvious the difference in BMI (p < .05). There was a significant difference in overweight/obesity between twins with a relative difference of birth weight ≥15% in DZ twins (p < .05). DZ twins, male twins and 0- to 6-year-old twins were more likely to be discordant in overweight/obese than others. The discordant birth weight within twins was not a risk factor for discordant overweight/obesity. However, attention should be paid to childhood obesity, and appropriate interventions should be made at the appropriate time. Genetics may play an important role in the occurrence and development of overweight/obesity. In conclusion, discordant growth and development in the uterus early in life may not lead to discordant weight development in the future. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate how different obesity measures link to circulating metabolites, and whether the connections are due to genetic or environmental factors. A cross-sectional analysis was performed on follow-up survey data at the Chinese National Twin Registry (CNTR), which was conducted in four areas of China (Shandong, Jiangsu, Zhejiang and Sichuan) in 2013. The survey collected detailed questionnaire information and conducted physical examinations, fasting blood sampling and untargeted metabolomic measurements among 439 adult twins. Linear regression models and bioinformatics analysis were used to examine the relation of obesity measures, including body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) with serum metabolite levels and related pathways. A co-twin control study was additionally conducted among 15 obesity-discordant monozygotic (MZ) pairs (intrapair BMI difference >3 kg/m2) to examine any differences in metabolites controlling for genetic factors. Eleven metabolites were associated with BMI, WC and WHR after controlling for genetic and shared environmental factors. Pathway analysis identified pathways such as phenylalanine metabolism, purine metabolism, valine, leucine and isoleucine biosynthesis that were associated with obesity. A wide range of unfavorable alterations in the serum metabolome was associated with obesity. Obesity-discordant twin analysis suggests that these associations are independent of genetic liability. [ABSTRACT FROM AUTHOR]

Objective: Few studies are available on birth asphyxia risks in twin neonates. This retrospective multi-center cross-sectional study determined the birthweight percentiles of 5337twins and birth asphyxia incidence of the twin population.Methods: We retrieved sociodemographic and obstetric data from the electronic records systems of participating centers. Neonate birthweight was measured within 24 h of birth. Perinatal asphyxia was diagnosed if 5-minute Apgar score was ≤5, or resuscitation was required 10 min after birth. The primary outcome was the incidence of birth asphyxia.Results: Totally 5337 neonates were eligible. The mean neonatal birthweight was 2227.1 ± 608.99 g and the 5th, 50th, and 95th percentiles of birthweight were 970, 2400, and 3080 g, respectively. The mean Apgar score was 9.06 ± 1.73 at 1 min and 8.99 ± 1.74 at 5 min. Totally 13.5 % (705/5222) twins had asphyxia and 9.35 % and 4.16 % twins had moderate and severe asphyxia, respectively. Twins with a birthweight< 1500 g had the highest asphyxia rate (64.8 %) and twins with a birthweight between 2500 and 3000 g had the lowest asphyxia rate (3.6 %). Stepwise logistic regression analysis revealed that higher birthweight was associated with a significantly reduced risk of asphyxia [OR 0.772 (95 %CI 0.755, 0.789), P < 0.001]. The AUROC for mean twin birthweight was 0.86±0.01 (95 %CI 0.84, 0.88) using a cutoff of 1950 g, with a sensitivity of 0.84 and a specificity of 0.78.Conclusion: Twins have lower birthweight versus singletons and a significant proportion of twins, especially twins with lower birthweight, are at risk of birth asphyxia. Birthweight is an independent predictor of asphyxia and should be further explored as a predictive marker for stratifying asphyxia risks in twin neonates. [ABSTRACT FROM AUTHOR]

The applicability of the CRISPR-Cas9 tool to the cure of several flaws in human embryos has raised up the number of worldwide basic and preclinical trials. By the end of 2018, the birth of the first genetically edited twins in China was known, intending to prevent them from catching HIV, since one of their parents had already suffered it. This led to social alarm, as the gestation process was carried out in disregard of medical standards and the assessments of ethics committees. The purpose of the present paper is to establish whether the intervention could be considered therapy, prevention – when trying to prevent an expected future pathology – or whether, in contrast, it would be, as has been widely defended, a clear case of enhancement, drawing the boundaries between all of them. To this end, the Declaration of the Spanish Bioethics Committee will be examined, highlighting some of their scientific, ethical and legal claims, and providing some comments that could call into question its original position. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to evaluate the preterm birth and additional perinatal outcomes between spontaneous and in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) dichorionic-diamnionic (DCDA) twin pregnancies.Material and Methods: This retrospective cohort study was conducted in a tertiary university-affiliated medical center. All women with DCDA twin pregnancies were considered for inclusion. The primary outcome of interest was preterm birth <37 weeks of gestation and secondary outcomes included spontaneous preterm birth, iatrogenic (induced) preterm birth, gestational diabetes mellitus, pregnancy-induced hypertensive disorder, preeclampsia, preterm premature rupture of membranes (PPROM), intrahepatic cholestasis of pregnancy, placenta previa, neonatal intensive care unit (NICU) admission, birthweight discordance, small for gestational age, neonatal respiratory distress syndrome, ventilator support, and perinatal death and/or severe morbidity. These outcomes were compared between IVF/ICSI and spontaneous twin pregnancies. Multivariable logistic regressions were used to adjust for confounders. General estimated equation models were used to address intertwin correlation.Results: A total of 1297 twin pregnancies, including 213 spontaneous and 1084 IVF/ICSI DCDA pregnancies, met the inclusion criteria. Women with IVF/ICSI pregnancies were older and had higher body mass index, adherence with prenatal care and proportion of nulliparity. After adjustment for confounders, IVF/ICSI pregnancies were associated with a slight increase in preterm birth <37 weeks of gestation (adjusted odds ratio [aOR] 1.72; 95% CI 1.24-2.39), iatrogenic preterm birth <37 weeks of gestation (aOR 1.41; 95% CI 1.00-1.97) as well as NICU admission (aOR 1.34; 95% CI 1.00-1.80). IVF/ICSI pregnancies were associated with a decrease in PPROM (aOR 0.64; 95% CI 0.42-0.99). There were no differences between IVF/ICSI and spontaneous DCDA pregnancies in terms of spontaneous preterm birth, gestational diabetes mellitus, pregnancy-induced hypertensive disorder, preeclampsia, intrahepatic cholestasis of pregnancy, placenta previa, birthweight discordance, small for gestational age, neonatal respiratory distress syndrome, ventilator support, and perinatal death and/or severe morbidity.Conclusions: IVF/ICSI DCDA twin pregnancies were associated with a slight increase in preterm birth <37 weeks of gestation, iatrogenic preterm birth <37 weeks of gestation, and NICU admission but with a decrease in PPROM. Other outcomes were comparable between IVF/ICSI and spontaneous DCDA twin pregnancies. Multicenter studies with adequate power remain warranted. [ABSTRACT FROM AUTHOR]

Objective: To investigate the association of folic acid (FA) supplementation with birth weight, the risk of small for gestational age (SGA) and low birth weight (LBW) in singleton and twin pregnancy.Design: A population-based cross-sectional survey.Setting: Twenty counties and ten districts in Shaanxi Province of northwestern China, 2013.Participants: 28 174 pregnant women with their infants, covering 27 818 single live births and 356 twin live births.Results: The prevalence of FA supplementation in singletons and twins was 63·9 and 66·3 %. The mean birth weight was 3267 (sd 459·1) g, 2525 (sd 534·0) g and 2494 (sd 539·5) g; the prevalence of SGA was 14·3, 51·4 and 53·4 %; the prevalence of LBW was 3·4, 42·4 and 46·6 % among singleton, twin A and twin B, respectively. Compared with non-users, women with FA supplementation were (β 17·3, 95 % CI 6·1, 28·4; β 166·3, 95 % CI 69·1, 263·5) associated with increased birth weight, lower risk of SGA (OR 0·85, 95 % CI 0·80, 0·92; OR 0·45, 95 % CI 0·30, 0·68) and LBW (OR 0·82, 95 % CI 0·71, 0·95; OR 0·50, 95 % CI 0·33, 0·75) in singletons and twins, and more prominent effects in twins. Moreover, there were significant interactions between FA supplementation and plurality on birth weight, SGA and LBW.Conclusions: The present study suggests the association of periconceptional 0·4 mg/d FA supplementation with increased birth weight and reduced risk of SGA and LBW in both singletons and twins, and this association may be more prominent in twins. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effects of antenatal corticosteroids (ACS) administration on mortality and major neonatal complications in early life of preterm twins.Study Design: This study retrospectively enrolled 1 662 twins delivered at 25∼34+6gestational weeks in China from January 2013 to December 2014. They were divided into ACS group and no-ACS group according to weather their mothers received ACS or not. Moreover, they were subgrouped as 25∼27+6 and 28∼34+6gestational week groups. Multivariable logistic regression was used to analyze the effects of ACS on the incidence of mortality and major morbidities.Results: A total of 910 neonates (54.8 %) received one or more doses of ACS, and 752 neonates (45.2 %) did not receive any ACS. No significant difference in infant mortality was observed between the ACS and no-ACS groups (P = 0.321). The ACS group had decreased incidence of respiratory distress syndrome (RDS) and mild RDS compared with the no-ACS group (both P < 0.05). There were no significant differences in the incidence of bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, retinopathy of prematurity, patent ductus arteriosus, sepsis and severe RDS between the two groups (all P > 0.05). The subgroup analysis showed that the incidence of RDS was lower in the ACS group than in the no-ACS group (P = 0.036) at 28∼34+6weeks. However, the incidence of mild ROP was higher in the ACS group than that in the no-ACS group (P = 0.047) at 25∼27+6 weeks. Multivariable logistic regression analysis demonstrated a decreasing risk of RDS (aOR = 0.661, 95 %CI:0.506-0.863, P = 0.002) after adjusting the gestational week, birth weight, small for gestational age, delivery mode, 5 min Apgar score, and maternal perinatal complications.Conclusion: In twin preterm infants, ACS administration is associated with a reduced risk of RDS. However, our data suggest that it may not have a beneficial effect on mortality and other short-term morbidities. [ABSTRACT FROM AUTHOR]

Aim: We evaluated the demographic of biliary atresia (BA) children from twins family and aimed to investigated what it can add to the twins' literature and our understanding of the disease.Methods: This study contains 11 medical centers in mainland China and the medical record of twins with BA was retrospectively analyzed from January 2012 to December 2018. Follow-up was carried out by out-patient review and questionnaire.Results: The study included 19 twin pairs in whom there was discordance for BA. Sixteen (84.2%) affected twin underwent Kasai Procedure (KP); median age at KP was 78 (49-168) days. There were ten affected twins that became jaundice-free at 3 months post-KP, and eight occurred with different degrees of cholangitis post-KP. Six affected twins received Liver Transplantation (LT) successfully. The 2 year native liver survival rate and the 2 year overall survival rate of affected twins were 61.1 and 94.4%, respectively. There were three affected monozygotic (MZ) twins and one healthy co-twin with BA-associated congenital malformations, all of which were cardiac malformations. The number of virus infection of affected MZ twins was significantly more (p = 0.04) than affected dizygotic (DZ) twin.Conclusions: Discordance for BA in 19 pairs of twins supported that BA may be related to genetic phenotype or penetrance. The difference in genetic background between MZ and DZ affects the susceptibility of the host to virus infection. High acceptance of KP (84.2%) in our study implied a high motivation for treatment for twins with BA. Delays of KP (78 days) in affected twin may be related to the postnatal gradual onset and the late diagnosis. [ABSTRACT FROM AUTHOR]

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable neurodevelopmental disorder. However, no study has examined genetic and environmental influences in the longitudinal developmental course of ADHD symptoms in a non-Western population. This study investigated changes of genetic and environmental influences and their contributions to the stability and change of ADHD symptoms of hyperactivity/impulsivity and inattention in Chinese adolescent twins. A prospective sample of 602 twin pairs (48% male) self-reported both DSM-IV ADHD symptom subscales three times at the approximate age of 12, 13, and 15 years. Longitudinal multivariate genetic analyses through structural equation modelling examined genetic and environmental contributions to the developmental course of ADHD symptoms. From early (time 1 and 2) to middle adolescence (time 3), both symptoms showed modest and non-significant genetic influences that became substantial and significant, whereas shared environmental influences were substantial and significant and became modest and non-significant. The same genetic factors influenced ADHD symptoms throughout adolescence, while shared and non-shared environmental influences largely came from new emerging factors. In early adolescence, genetic factor contributed to the stability of inattention, whereas shared environmental factor contributed to the stability of hyperactivity/impulsivity. Genetic influences of ADHD tended to be smaller, whereas shared environmental influences tended to be larger in Chinese than in Western populations. Genetic factors played a large role in the stability of ADHD throughout adolescence, while shared and non-shared environment primarily contributed to its change. Findings highlight the importance of shared family, neighbourhood, and community experiences on child psychopathology in a collectivistic culture such as the Chinese society. [ABSTRACT FROM AUTHOR]

This article explores the justification for providing separate experiences for twins. The focus is on Dorothy Burlingham's (1952; Twins: A study of three sets of identical twins with 30 charts. London, UK: Imago) classic, in-depth study of three identical twin-pairs. Implications for how twins are raised currently will be examined. Reviews are presented of twin research concerning monozygotic twins with maturity-onset diabetes, gene editing of fetal Chinese twins, educational disadvantage of early-born twins, and developmental trajectories of twins' prenatal movements. Some unusual experiences and situations involving twins that warrant media attention are also summarized. They include twins with nearly identical license plates, a rare case of fetus-in-fetu, twin brothers killed at Pearl Harbor, the death of a 96-year-old twin Holocaust survivor, the accidental death of male-female twin toddlers in a heated car and confusion over identical twin politicians. [ABSTRACT FROM AUTHOR]

The article offers information on future of gene editing. Topics discussed include most frequently mentioned risks posed by germline editing are off-target mutations that raise the specter of cancer; scientists could somehow guarantee that editing a particular gene would cause no catastrophic, lasting, or untreatable harm far down the line; and views on genomewide association study that revealing an association between a particular polygenic risk score and educational attainment.

Background: Congenital insensitivity to pain with anhidrosis is a rare autosomal recessive disorder characterized by hyperpyrexia, anhidrosis, pain insensitivity, self-inflicted injuries, and intellectual disability. The anesthetic management of these patients is challenging owing to the high risk of perioperative complications resulting from their autonomic dysfunction, such as hyperthermia, hypotension, and bradycardia, which result from autonomic nervous system dysfunction.Case Presentation: Two 3-year-old Han Chinese identical male twins (weighing 13.5 kg and measuring 93 cm tall) were previously diagnosed as having congenital insensitivity to pain with anhidrosis based on clinical features and genetic screening. According to the presence of loud snoring and heavy breathing during sleep and neck radiograph findings, they were diagnosed as having tonsil and adenoid hypertrophy and needed adenotonsillectomy. Because of innate analgesia, some reports suggested that patients with congenital insensitivity to pain with anhidrosis do not require perioperative pain control. Accordingly, our patients did not receive opiates. We describe the general anesthetic management of these patients using sevoflurane and propofol, but without opiates, for adenotonsillectomy. Remarkable tachycardia and hypertension occurred during airway manipulation and when the surgical stimuli increased, and their temperatures increased from 36 °C and 36.8 °C to 37.8 °C and 38.5 °C, respectively. Patients with congenital insensitivity to pain with anhidrosis lack pain sensation, but they may have tactile hyperesthesia. Surgical noxious stimuli may therefore produce a stress response and unpleasant sensations, leading to hemodynamic fluctuation and temperature increase.Conclusions: On the basis of these findings, we suggest that careful intraoperative opiate titration may be justified to blunt the surgical stress response and promote hemodynamic and temperature stability in similar patients; we also recommend the preparation of warming and cooling devices and continuous temperature monitoring in these patients. Since anesthetic management of these patients is not simple, careful attention is required. [ABSTRACT FROM AUTHOR]

The Wuhan Pre/Post-Natal Twin Birth Registry (WPTBR) is one of the largest twin birth registries with comprehensive medical information in China. It recruits women from the first trimester of pregnancy and their twins from birth. From January 2006 to May 2016, the total number of twins enrolled in WPTBR is 13,869 twin pairs (27,553 individuals). The WPTBR initiated the Wuhan Twin Birth Cohort (WTBC). The WTBC is a prospective cohort study carried out through incorporation of three samples. The first one comprises 6,920 twin pairs, and the second one, 6,949 twin pairs. Both are population-based samples linked to the WPTBR and include pre- and post-natal information from WPTBR. The second sample includes neonatal blood spots as well. Using a hospital-based approach, we recently developed a third sample with a target enrolment of 1,000 twin pairs and their mothers. These twins are invited, via their parents, to participate in a periodic health examination from the first trimester of pregnancy to 18 years. Biological samples are collected initially from the mother, including blood, urine, cord blood, cord, amniotic fluid, placenta, breast milk and meconium, and vaginal secretions, and later from the twins, including meconium, stool, urine, and blood. This article describes the design, recruitment, follow-up, data collection, and measures, as well as ongoing and planned analyses at the WTBC. The WTBC offers a unique opportunity to follow women from prenatal to postnatal, as well as follow-up of their twins. This cohort study will expand the understanding of genetic and environmental influences on pregnancy and twins’ development in China. [ABSTRACT FROM PUBLISHER]

Obesity is associated with blood pressure (BP), but the associations between different obesity indicators and BP have not reached agreement. Besides, both obesity and BP are influenced by genetic and environmental factors. Whether they share the same genetic or environmental etiology has not been fully understood. We therefore analyzed the relationship between different obesity indicators and BP components as well as the genetic and environmental contributions to these relationships in a Chinese adult twin sample. Twins aged 18–79 years (n = 941) were included in this study. Body mass index (BMI) was used as the index of general obesity, whereas waist circumference (WC), waist-to-height ratio (WHtR), and waist-to-hip ratio (WHR) were used as the indicators of central obesity. BP components included systolic blood pressure (SBP) and diastolic blood pressure (DBP). Linear regression models and bivariate structural equation models were used to examine the relation of various obesity indicators with BP components, and genetic or environmental influences on these associations, respectively. A strong association of BP components with BMI—and a somewhat weaker association with WC, WHtR, and WHR—was found in both sexes, independent of familial factors. Of these phenotypic correlations between obesity indicators and BP components, 60–76% were attributed to genetic factors, whereas 24–40% were attributed to unique environmental factors. General obesity was most strongly associated with high BP in Chinese adult twins. There were common genetic backgrounds for obesity and BP, and unique environmental factors also played a role. [ABSTRACT FROM PUBLISHER]

Although the correlation between cognition and physical function has been well studied in the general population, the genetic and environmental nature of the correlation has been rarely investigated. We conducted a classical twin analysis on cognitive and physical function, including forced expiratory volume in one second (FEV1), forced vital capacity (FVC), handgrip strength, five-times-sit-to-stand test (FTSST), near visual acuity, and number of teeth lost in 379 complete twin pairs. Bivariate twin models were fitted to estimate the genetic and environmental correlation between physical and cognitive function. Bivariate analysis showed mildly positively genetic correlations between cognition and FEV1, r G = 0.23 [95% CI: 0.03, 0.62], as well as FVC, r G = 0.35 [95% CI: 0.06, 1.00]. We found that FTSST and cognition presented very high common environmental correlation, r C = -1.00 [95% CI: -1.00, -0.57], and low but significant unique environmental correlation, r E = -0.11 [95% CI: -0.22, -0.01], all in the negative direction. Meanwhile, near visual acuity and cognition also showed unique environmental correlation, r E = 0.16 [95% CI: 0.03, 0.27]. We found no significantly genetic correlation for cognition with handgrip strength, FTSST, near visual acuity, and number of teeth lost. Cognitive function was genetically related to pulmonary function. The FTSST and cognition shared almost the same common environmental factors but only part of the unique environmental factors, both with negative correlation. In contrast, near visual acuity and cognition may positively share part of the unique environmental factors. [ABSTRACT FROM AUTHOR]

Genetic and environmental influences on predictors of decline in daily functioning, including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), handgrip, and five-times-sit-to-stand test (FTSST), have not been addressed in the aging Chinese population. We performed classical twin modeling on FEV1, FVC, handgrip, and FTSST in 379 twin pairs (240 MZ and 139 DZ) with median age of 50 years (40–80 years). Data were analyzed by fitting univariate and bivariate twin models to estimate the genetic and environmental influences on these measures of physical function. Heritability was moderate for FEV1, handgrip, and FTSST (55–60%) but insignificant for FVC. Only FVC showed moderate control, with shared environmental factors accounting for about 50% of the total variance. In contrast, all measures of pulmonary function and muscle strength showed modest influences from the unique environment (40–50%). Bivariate analysis showed highly positive genetic correlations between FEV1 and FVC (rG = 1.00), and moderately negative genetic correlations between FTSST and FEV1 (rG = −0.33) and FVC (rG = −0.42). FEV1 and FVC, as well as FEV1 and handgrip, displayed high common environmental correlations (rC = 1.00), and there were moderate correlations between FVC and handgrip (rC = 0.44). FEV1 and FVC showed high unique environmental correlations (rE = 0.76) and low correlations between handgrip and FEV1 (rE = 0.17), FVC (rE = 0.14), and FTSST (rE = −0.13) with positive or negative direction. We conclude that genetic factors contribute significantly to the individual differences in common indicators of daily functioning (FEV1, handgrip, and FTSST). FEV1 and FVC were genetically and environmentally correlated. Pulmonary function and FTSST may share similar sets of genes but in the negative direction. Pulmonary function and muscle strength may have a shared environmental background. [ABSTRACT FROM PUBLISHER]

One salient characteristic of twin studies and the related behavioral genetics paradigm is the requirement of a large sample size. Countries or regions that are large in size and highly populated are at an advantage when implementing twin studies. However, given the fascinating and promising results obtained from twin studies, many researchers based in smaller countries or regions may still want to conduct twin studies in order to address local and theoretical issues. In this article, we have outlined the development of twin studies in Hong Kong, one of the Special Administrative Regions of China. The historical development and design of the two major twin studies of language and reading development implemented within Hong Kong are discussed, providing insights to researchers who also aspire to conduct twin studies in small regions. [ABSTRACT FROM AUTHOR]

The aim of the present work was to determine maternal and fetal outcomes of intrahepatic cholestasis of pregnancy (ICP) in twin pregnancies. All twin pregnancies delivered above 28 gestational weeks in West China Second University Hospital from January 2013 to May 2015 were included. Data on maternal demographics and obstetric complications together with fetal outcomes were collected. The risk of adverse maternal and fetal outcomes were determined in relation to ICP by crude odds ratios (OR) and adjusted ORs (aOR) with 95% confidence intervals (CI). Subgroup analysis concentrated on the effect of assisted reproductive technology (ART), ICP severity, and onset time. A total of 1,472 twin pregnancies were included, of which 362 were cholestasis patients and 677 were conceived by ART. Higher rates of preeclampsia (aOR 1.96; 95% CI 1.35, 2.85), meconium-stained amniotic fluid (aOR 3.10; 95% CI 2.10, 4.61), and preterm deliveries (aOR 3.20; 95% CI 2.35, 4.37) were observed in ICP patients. Subgroup analysis revealed higher incidences of adverse outcomes in severe and early onset ICP groups. In conclusion, adverse maternal and fetal outcomes were strongly associated with ICP in twin patients. Active management and close antenatal monitoring are needed, especially in the early onset and severe groups. [ABSTRACT FROM PUBLISHER]

Background: Despite evidence for some genetic control of dietary intake in adults, there is little evidence of how genetic factors influence children's dietary patterns.Objective: To estimate heritability of dietary intake in twin children from China and test if genetic effects on dietary intakes vary by the children's socio-economic status (SES).Methods: A sample of 622 twins (162 monozygotic and 149 dizygotic pairs; 298 boys and 324 girls aged 7-15 years) was recruited in South China. Dietary intakes were assessed using a validated 145-item semi-quantitative food frequency questionnaire. Pooled and sex-specific dietary patterns were identified using factor analysis. Heritability was estimated using structural equation models.Results: Heritable components differed by gender and for nutrients and food groups; and estimated heritability of dietary patterns was generally greater in girls than boys. In boys, estimated heritabilities ranged from 18.8% (zinc) to 58.4% (fat) for nutrients; and for food group, 1.1% (Western fast foods) to 65.8% (soft drinks). In girls, these estimates ranged from 5.1% (total energy) to 38.7% (percentage of energy from fat) for nutrients, and 12.6% (eggs) to 94.6% (Western fast foods) for food groups. Factor analysis identified five food patterns: vegetables and fruits, fried and fast foods, beverages, snacks and meats. Maternal education and family income were positively associated with higher heritabilities for intake of meat, fried, and fast food.Conclusions: Genetic influence on dietary intakes differed by gender, nutrients, food groups, and dietary patterns among Chinese twins. Parental SES characteristics modified the estimated genetic influence. [ABSTRACT FROM AUTHOR]

Background. Twin and family studies using Western samples have established that child and adolescent anxiety and depression are under substantial genetic, modest shared environmental, and substantial non-shared environmental influences. Generalizability of these findings to non-Western societies remains largely unknown, particularly regarding the changes of genetic and environmental influences with age. The current study examined changes in genetic and environmental influences on self-reported anxiety and depression from late childhood to mid-adolescence among a Chinese twin sample. Sex differences were also examined. Method. Self-reported anxiety and depression were collected from 712 10- to 12-year-old Chinese twins (mean = 10.88 years, 49% males) and again 3 years later. Quantitative genetic modeling was used to examine developmental changes in genetic and environmental influences on anxiety and depression, and sex differences. Results. Heritability of anxiety and depression in late childhood (23 and 20%) decreased to negligible in mid-adolescence, while shared environmental influences increased (20 and 27% to 57 and 60%). Shared environmental factors explained most of the continuity of anxiety and depression (75 and 77%). Non-shared environmental factors were largely time-specific. No sex differences were observed. Conclusions. Shared environmental influences might be more pronounced during the transition period of adolescence in non-Western societies such as China. Future research should examine similarities and differences in the genetic and environmental etiologies of child and adolescent internalizing and other psychopathology in development between Western and non-Western societies. [ABSTRACT FROM AUTHOR]

Objective: To identify the association between preeclampsia (PE) and selective intrauterine growth restriction (sIUGR) in twin pregnancies.Methods: This was a retrospective cohort study of 1004 twin pregnancies from 2008 to 2014. We specifically compared the incidence, clinical characteristics and outcomes of PE between sIUGR and normal-growth twin pregnancies.Results: PE occurred more frequently in sIUGR pregnancies [29.0% (51/176)] than in normal-growth twin pregnancies [13.1% (99/756), p < 0.001, adjusted odds ratio 3.29]. Among sIUGR, the incidence of PE was significantly higher in dichorionic (DC) pregnancies (37.5%, 30/80) than in monochorionic (MC) pregnancies (21.9%, 21/96). The rates of onset at <32 weeks (p = 0.045) and of severe PE (p = 0.025) were higher in sIUGR pregnancies with PE. The systolic blood pressure was also higher in sIUGR pregnancies with PE (152.6 ± 11.8 mmHg) than in normal-growth pregnancies with PE (148.0 ± 8.2 mmHg) (p = 0.042). Additionally, more sIUGR pregnancies were delivered at 32-36 weeks (p = 0.001), and fewer were delivered at ≥36 weeks (p < 0.001). Moreover, the prevalence of severe neonatal asphyxia was higher in sIUGR pregnancies with PE than in normal-growth pregnancies with PE (8.8% versus 2.5%, p = 0.020).Conclusions: sIUGR is associated with increased odds of developing severe PE in twin pregnancies, leading to poorer perinatal outcomes. [ABSTRACT FROM AUTHOR]

Background: Obesity is a multifactorial abnormality which has an underlying genetic control but requires environmental influences to trigger. Numerous epidemiological studies have examined the roles of physical inactivity and dietary factors in obesity development. Interactions between obesity-related genes and these lifestyles have also been confirmed. However, less attention has been paid to these complex relationship between cigarette smoking, alcohol drinking and obesity. The purpose of this study was to assess whether cigarette smoking and alcohol drinking were associated with body mass index (BMI), and whether these lifestyle factors modified the genetic variance of BMI.Methods: Subjects were twins recruited through the Chinese National Twin Registry, aged 18 to 79 years, and the sample comprised 6121 complete male twin pairs. Information on height, weight, cigarette smoking and alcohol drinking status were assessed with self-report questionnaires. The associations of cigarette smoking and alcohol drinking with BMI were evaluated by linear regression models. Further, structure equation models were conducted to estimate whether cigarette smoking and alcohol drinking status modified the degree of genetic variance of BMI.Results: After adjustment for a variety of socio-demographic and lifestyle factors, former smokers had higher BMI (β = 0.475; 95 % CI, 0.196 to 0.754) whereas moderate to heavy smokers had lower BMI (β = -0.115; 95 % CI, -0.223 to -0.007) when compared with nonsmokers. BMI decreased with increased cigarette pack-years (β = -0.008; 95 % CI, -0.013 to -0.003). These effects still existed substantially in within-MZ twin pair analyses. By contrast, current alcohol drinking had no significant influence on BMI when additionally controlled for shared factors in within-pair analyses. Genetic modification by alcohol drinking was statistically significant for BMI (β = -0.137; 95 % CI, -0.215 to -0.058), with the intake of alcohol decreasing the additive genetic component of BMI.Conclusions: Cigarette smoking was negatively associated with BMI independent of genetic influences. The influence of genes on BMI was moderated by alcohol drinking, such that for individuals who were regular drinkers, genetic factors became less influential. Our findings highlight gene-alcohol interaction in finding candidate genes of BMI and elucidating the etiological factors of obesity. [ABSTRACT FROM AUTHOR]

Background.Neurological soft signs (NSS) have long been considered potential endophenotypes for schizophrenia. However, few studies have investigated the heritability and familiality of NSS. The present study examined the heritability and familiality of NSS in healthy twins and patient–relative pairs.Method.The abridged version of the Cambridge Neurological Inventory was administered to 267 pairs of monozygotic twins, 124 pairs of dizygotic twins, and 75 pairs of patients with schizophrenia and their non-psychotic first-degree relatives.Results.NSS were found to have moderate but significant heritability in the healthy twin sample. Moreover, patients with schizophrenia correlated closely with their first-degree relatives on NSS.Conclusions.Taken together, the findings provide evidence on the heritability and familiality of NSS in the Han Chinese population. [ABSTRACT FROM PUBLISHER]

This study examined the genetic and environmental effects on variances in weight, height, and body mass index (BMI) under 18 years in a population-based sample from China. We selected 6,644 monozygotic and 5,969 dizygotic twin pairs from the Chinese National Twin Registry (CNTR) aged under 18 years (n = 12,613). Classic twin analyses with sex limitation were used to estimate the genetic and environmental components of weight, height, and BMI in six age groups. Sex-limitation of genetic and shared environmental effects was observed, especially when puberty begins. Heritability for weight, height, and BMI was low at 0–2 years old (less than 20% for both sexes) but increased over time, accounting for half or more of the variance in the 15–17 year age group for boys. For girls, heritabilities for weight, height and BMI was maintained at approximately 30% after puberty. Common environmental effects on all body measures were high for girls (59–87%) and presented a small peak during puberty. Genetics appear to play an increasingly important role in explaining the variation in weight, height, and BMI from early childhood to late adolescence, particularly in boys. Common environmental factors exert their strongest and most independent influence specifically in the pre-adolescent period and more significantly in girls. These findings emphasize the need to target family and social environmental interventions in early childhood years, especially for females. Further studies about puberty-related genes and social environment are needed to clarify the mechanism of sex differences. [ABSTRACT FROM PUBLISHER]

BackgroundLittle is known about the etiology of adolescents’ externalizing behavior (Ext) in collectivistic cultures. We aimed to fill this gap by investigating the genetic and environmental influences on Ext in Chinese adolescents. The etiological heterogeneity of aggression (AGG) and rule breaking (RB) was also examined.MethodThe study sample included 908 pairs of same-sex twins aged from 10 to 18 years (mean = 13.53 years, s.d. = 2.26). Adolescents’ Ext were assessed with the Achenbach System of Empirically Based Assessment including Child Behavior Checklist, Teacher Report Form, and Youth Self-Report.ResultsUnivariate genetic analyses showed that genetic influences on all measures were moderate ranging from 34% to 50%, non-shared environmental effects ranged from 23% to 52%, and shared environmental effects were significant in parent- and teacher-reported measures ranging from 29% to 43%. Bivariate genetic analyses indicated that AGG and RB shared large genetic influences (rg = 0.64–0.79) but moderate non-shared environmental factors (re = 0.34–0.52).ConclusionsChinese adolescents’ Ext was moderately influenced by genetic factors. AGG and RB had moderate independent genetic and non-shared environmental influences, and thus constitute etiologically distinct dimensions within Ext in Chinese adolescents. The heritability of AGG, in particular, was smaller in Chinese adolescents than suggested by previous data obtained on Western peers. This study suggests that the collectivistic cultural values and Confucianism philosophy may attenuate genetic potential in Ext, especially AGG. [ABSTRACT FROM AUTHOR]

Background Child and adolescent anxiety has become a major public health concern in China, but little was known about the etiology of anxiety in Chinese children and adolescents. The present study aimed to investigate genetic and environmental influences on trait anxiety among Chinese children and adolescents. Rater, sex, and age differences on these estimates were also examined. Methods Self-reported and parent-reported child's trait anxiety was collected from 1,104 pairs of same-sex twins aged 9-18 years. Genetic models were fitted to data from each informant to determine the genetic (A), shared (C), and non-shared environmental (E) influences on trait anxiety. Results The parameter estimates and 95% confidence intervals ( CI) of A, C, E on self-reported trait anxiety were 50% [30%, 60%], 5% [0%, 24%], 45% [40%, 49%]. For parent-reported data, the corresponding parameter estimates were 63% [47%, 78%], 13% [1%, 28%], and 24% [22%, 27%], respectively. The heritability of anxiety was higher in girls for self-reported data, but higher in boys for parent-reported data. There was no significant age difference in genetic and environmental contributions for self-reported data, but a significant increase of heritability with age for parent-reported data. Conclusions The trait anxiety in Chinese children and adolescents was highly heritable. Non-shared environmental factors also played an important role. The estimates of genetic and environmental effects differed by rater, sex and age. Our findings largely suggest the cross-cultural generalizability of the etiological model of child and adolescent anxiety. [ABSTRACT FROM AUTHOR]

Background: the genetic and environmental contributions to cognitive function in the old people have been well addressed for the Western populations using twin modelling showing moderate to high heritability. No similar study has been conducted in the world largest and rapidly ageing Chinese population living under distinct environmental condition as the Western populations. Objective: this study aims to explore the genetic and environmental impact on normal cognitive ageing in the Chinese twins. Design/setting: cognitive function was measured on 384 complete twin pairs with median age of 50 years for seven cognitive measurements including visuospatial, linguistic skills, naming, memory, attention, abstraction and orientation abilities. Data were analysed by fitting univariate and bivariate twin models to estimate the genetic and environmental components in the variance and co-variance of the cognitive assessments. Results: intra-pair correlation on cognitive measurements was low to moderate in monozygotic twins (0.23-0.41, overall 0.42) and low in dizygotic twins (0.05-0.30, overall 0.31) with the former higher than the latter for each item. Estimate for heritability was moderate for overall cognitive function (0.44, 95% CI: 0.34-0.53) and low to moderate for visuospatial, naming, attention and orientation abilities ranging from 0.28 to 0.38. No genetic contribution was estimated to linguistic skill, abstraction and memory which instead were under low to moderate control by shared environmental factors accounting for 23-33% of the total variances. In contrast, all cognitive performances showed moderate to high influences by the unique environmental factors. Conclusions: genetic factor and common family environment have a limited contribution to cognitive function in the Chinese adults. Individual unique environment is likely to play a major role in determining the levels of cognitive performance. [ABSTRACT FROM AUTHOR]

Adult health outcomes and health behaviors are often associated with schooling. However, such associations do not necessarily imply that schooling has causal effects on health with the signs or magnitudes found in the cross-sectional associations. Schooling may be proxying for unobserved factors related to genetics and family background that directly affect both health and schooling. Recently several studies have used within-monozygotic (MZ) twins methods to control for unobserved factors shared by identical twins. Within-MZ estimates for developed countries are generally smaller than suggested by cross-sectional associations, consistent with positive correlations between unobserved factors that determine schooling and those that determine health. This study contributes new estimates of cross-sectional associations and within-MZ causal effects using the Chinese Adults Twins Survey, the first study of its type for developing countries. The cross-sectional estimates suggest that schooling is significantly associated with adult health-related behaviors (smoking, drinking, exercising) but not with own or spouse health outcomes (general health, mental health, overweight, chronic diseases). However, within-MZ-twins estimators change the estimates for approximately half of these health indicators, in one case declining in absolute magnitudes and becoming insignificant and in the other cases increasing in absolute magnitudes. Within-MZ estimates indicate significant pro-health effects for at least one of the indicators for own health (better mental health), own health-related behaviors (less smoking) and spouse health (less overweight). [ABSTRACT FROM AUTHOR]

Systolic and diastolic blood pressure, pulse pressure (PP), and body mass index (BMI) are heritable traits in human metabolic health but their common genetic and environmental backgrounds are not well investigated. The aim of this article was to explore the phenotypic and genetic associations among PP, systolic blood pressure (SBP), diastolic blood pressure (DBP), and BMI. The studied sample contained 615 twin pairs (17–84 years) collected in the Qingdao municipality. Univariate and multivariate structural equation models were fitted for assessing the genetic and environmental contributions. The AE model combining additive genetic (A) and unique environmental (E) factors produced the best fit for each four phenotypes. Heritability estimated in univariate analysis ranged from 0.42 to 0.74 with the highest for BMI (95% CI 0.70–0.78), and the lowest for PP (95% CI 0.34–0.49). The multivariate model estimated (1) high genetic correlations for DBP with SBP (0.87), PP with SBP (0.75); (2) low–moderate genetic correlations between PP and DBP (0.32), each BP component and BMI (0.24–0.37); (3) moderate unique environmental correlation for PP with SBP (0.68) and SBP with DBP (0.63); (4) there was no significant unique environmental correlation between PP and BMI. Overall, our multivariate analyses revealed common genetic and environmental backgrounds for PP, BP, and BMI in Chinese twins. [ABSTRACT FROM PUBLISHER]

Abstract: Purpose: To evaluate the credibility of twin status as an instrumental variable for birth weight and infant growth and to obtain less-confounded estimates of the associations of birth weight or infant growth with adolescent blood pressure (BP). Methods: Prospective population-based “Children of 1997” birth cohort of all surviving infants born in Hong Kong, China, from April to May 1997 with sex-, age-, and height-specific BP z-score at approximately 11 years (n = 6276) and approximately 13 years (n = 5305). Results: In instrumental variable analyses, birth weight-for-gestational age z-score was not associated with z-score for systolic BP (0.01; 95% confidence interval [CI], −0.22 to 0.25) or diastolic BP (0.04; 95% CI, −0.09 to 0.18) at approximately 11 years adjusted for maternal age and migrant status (F = 38.6). Change in weight z-score at 0 to 12 months was not associated with z-score for systolic BP (−0.003; 95% CI, −0.15 to 0.15) or diastolic BP (−0.02; 95% CI, −0.10 to 0.07) at approximately 11 years (F = 54.4). Estimates were similar for BP at approximately 13 years, although the F-statistic was lower. Conclusions: Birth weight and infant growth may make little contribution to adolescent BP. Extending consideration of the effects of early life to other growth periods, such as puberty, on BP might yield public health benefits. [Copyright &y& Elsevier]

We evaluated the genetic and environmental contributions to metabolic cardiovascular risk factors and their mutual associations. Eight metabolic factors (body mass index, waist circumference, waist-to-hip ratio, systolic blood pressure, diastolic blood pressure, total serum cholesterol, serum triglycerides, and serum uric acid) were measured in 508 twin pairs aged 8–17 years from the Qingdao Twin Registry, China. Linear structural equation models were used to estimate the heritability of these traits, as well as the genetic and environmental correlations between them. Among boys, body mass index and uric acid showed consistently high heritability (0.49–0.81), whereas other traits showed moderate to high common environmental variance (0.37–0.73) in children (8–12 years) and adolescents (13–17 years) except total cholesterol. For girls, moderate to high heritability (0.39–0.75) were obtained for six metabolic traits in children, while only two traits showed high heritability and others mostly medium to large common environmental variance in adolescents. Genetic correlations between the traits were strong in both boys and girls in children (rg = 0.64–0.99 between body mass index and diastolic blood pressure; rg = 0.71–1.00 between body mass index and waist circumference), but decreased for adolescent girls (rg = 0.51 between body mass index and waist-to-hip ratio; rg = 0.55 between body mass index and uric acid; rg = 0.61 between body mass index and systolic blood pressure). The effect of genetic factors on most metabolic traits decreased from childhood to adolescence. Both common genetic and specific environmental factors influence the mutual associations among most of the metabolic traits. [ABSTRACT FROM PUBLISHER]

We aimed to analyze how genetic and environmental factors account for variations in body mass index (BMI), waist circumference (WC) and their mutual correlation in Chinese children. We measured BMI and WC in 588 pairs of twins (53 % monozygotic twins) aged 8-17 years and applied structural equation modeling to the data. For the younger children (8-12 years of age), heritability estimates of BMI were 0.56 for boys and 0.69 for girls; for the older children (13-17 years of age), the corresponding figures were 0.64 and 0.71, respectively. We observed moderate heritability estimates in WC: the corresponding figures were 0.24 and 0.56 for the younger children, and 0.27 and 0.33 for the older children, respectively. The heterogeneity test for genetic variance of BMI and WC was statistically significant between the two age groups for both sexes ( p < 0.001). The proportions of BMI and WC variations due to shared and non-shared environmental factors remained stable during childhood in both sexes. Bivariate genetic analyses showed that genetic correlations between BMI and WC were strong for the younger children (r = 0.75 for boys, r = 0.98 for girls) and the older children (r = 1.0 for both boys and girls). Both sexes showed moderate non-shared environmental correlations in the two age groups, whereas shared environmental correlations--except among male younger children--were not statistically significant. Genetic factors play an important role in variations in BMI and WC during childhood. Common genetic and non-shared environmental factors explained most of the association between BMI and WC for both boys and girls. [ABSTRACT FROM AUTHOR]

Non-shared parenting and deviant peer affiliation are linked to differences in externalizing behaviors between twins. However, few studies have examined these two non-shared environments simultaneously. The present study examined the transactional roles of differential parenting (i.e., warmth and hostility) and deviant peer affiliation on monozygotic (MZ) twin differences in externalizing behaviors using a two-wave longitudinal study of twins and their parents. The sample consisted of 520 pairs of MZ twins (46.5% males, 53.5% females), with a mean age of 13.86 years (SD = 2.10) at the T1 assessment, residing in Beijing, China. The association between non-shared hostility in parenting and adolescent externalizing behaviors was mainly explained by a child-driven effect whereby the twin with a higher level of externalizing behaviors than his or her co-twin was more likely to receive more hostility from the parents. Similarly, the relationship between deviant peer affiliation and adolescent externalizing behaviors supported the selection effect whereby the twin with a higher level of externalizing behaviors than his or her co-twin was more likely to affiliate with deviant peers. The theoretical and practical implications of these findings are discussed. [ABSTRACT FROM PUBLISHER]

The Chinese National Twin Registry (CNTR), established in 2001, is the first and largest population-based twin registry in China. Based on the CNTR, a new twin cohort was recruited from 2011 to study the relationship between environmental risk factors and chronic diseases. So far, 33,874 twin pairs from nine provinces have been recruited, in which hundreds of disease-discordant twin pairs and even thousands of exposure-discordant twin pairs were found in this cohort. The updates of the CNTR will be introduced in detail in this article. [ABSTRACT FROM AUTHOR]

The Guangzhou Twin Registry is a population-based registry of twins residing in Guangzhou City. The initial registry database included 9,700 pairs of young twins recruited from the Official Household Registry of Guangzhou City. The registry is designed to provide a resource to identify the genetic and environmental causes of common diseases with an initial focus on eye diseases. From 2006 onward, phenotype and DNA collection have been completed for more than 1,200 twin pairs and their parents or siblings. Most of the young twins have come back for an annual examination of the progressive traits, such as refraction, ocular biometry, weight, and height. Genome-wide association scans have been completed recently. This article gives an update of the study design, cohort profile, previous findings, and future directions. Results from the Guangzhou Twin Project may contribute to the understanding of gene-environmental interplay for complex diseases in both adults and children. [ABSTRACT FROM AUTHOR]

Rates of emotional and behavioral problems among children and adolescents in China are increasing and represent a major public health concern. To investigate the etiology of such problems, including the effects and interplay of genes and environment, the Beijing Twin Study (BeTwiSt) was established. A representative sample of adolescent twins in Beijing (N = 1,387 pairs of adolescent twins, mostly between the ages of 10 and 18 years) was recruited and assessed longitudinally. Data collection included the following: emotional and behavioral problems (e.g., depressive symptoms, anxiety, delinquency, drinking, and smoking); family, peer, and school environments; stress; social and academic competence; cognitive traits (e.g., emotion suppression, rumination, and effortful control); and saliva samples for DNA genotyping and sequencing. The combination of quantitative and molecular genetic approaches and the timeliness of the project, with the sample residing in a region with a rapidly changing economic and cultural climate, are particular strengths of this study. Findings from this study are expected to help understanding of the etiological mechanisms underlying child and adolescent normal and abnormal development in regions undergoing substantial social, cultural, and economic changes. [ABSTRACT FROM AUTHOR]