Several neuroimaging studies have reported associations between brain white matter microstructure and chronotype. However, it is unclear whether those phenotypic relationships are causal or underlined by genetic factors. In the present study, we use genetic data to examine the genetic overlap and infer causal relationships between chronotype and diffusion tensor imaging (DTI) measures. We identify 29 significant pairwise genetic correlations, of which 13 also show evidence for a causal association. Genetic correlations were identified between chronotype and brain-wide mean, axial and radial diffusivities. When exploring individual tracts, 10 genetic correlations were observed with mean diffusivity, 10 with axial diffusivity, 4 with radial diffusivity and 2 with mode of anisotropy. We found evidence for a possible causal association of eveningness with white matter microstructure measures in individual tracts including the posterior limb and the retrolenticular part of the internal capsule; the genu and splenium of the corpus callosum and the posterior, superior and anterior regions of the corona radiata. Our findings contribute to the understanding of how genes influence circadian preference and brain white matter and provide a new avenue for investigating the role of chronotype in health and disease.

The present study aimed to determine the genetic and environmental etiology of the association between childhood negative emotionality (NE) and hyperactivity/inattention problems (HIP) using South Korean elementary school twins (mean age = 10.19 years, SD = 1.79 years). Telephone interviews were given to mothers of 919 twins (229 monozygotic males: 112 pairs and 5 individuals; 148 dizygotic males: 73 pairs and 2 individuals; 180 monozygotic females: 87 pairs and 6 individuals; 103 dizygotic females: 50 pairs and 3 individuals; 259 opposite-sex dizygotic twins: 127 pairs and 5 individuals) to assess their children’s NE and HIP. Consistent with prior studies, the phenotypic correlation between NE and the HIP was moderate (r = .29; 95% CI = .24, .34). Model-fitting analysis revealed that additive genetic and nonshared environmental influences on NE were .45 (95% CI [.34, .54]) and .55 (95% CI [.46, .66]), respectively, and that additive and nonadditive genetic, and nonshared environmental influences on HIP were .08 (95% CI [.03, .26]), .41 (95% CI [.21, .51]) and .51 (95% CI = .42, .61), respectively. In addition, the additive genetic correlation between NE and HIP was 1.0 (95% CI [.52, 1.00]), indicating that additive genetic factors are entirely shared between the two phenotypes. Nonadditive genetic influences were unique to HIP and not responsible for the NE-HIP association. Nonshared environmental correlation was significant but modest (re = .18, 95% CI [.06, .30]).

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.

The purpose of our study was to elucidate the functions of miR-30c-5p on adenomyosis for exploring novel treatment strategies. We first detected the expression of miR-30c-5p in clinical adenomyotic tissues and isolated endometrial cells from adenomyotic tissues. Next, gain and loss-of-function assays were performed to detect the effect of miR-30c-5p on adenomyotic endometrial cells. Further, luciferase assay and real-time polymerase chain reaction as well as western blot were conducted to investigate the potential target of miR-30c-5p; and transwell assay, wound-healing assay and CCK-8 assay were used to evaluate the effects of miR-30c-5p and its target on regulating biological functions of adenomyotic endometrial cells. Our results found that miR-30c-5p was down-regulated in both adenomyosis tissues and adenomyotic epithelial cells, which correlated with dysmenorrhea, longer duration of symptoms and more menstrual bleeding. Moreover, the overexpression of miR-30c-5p inhibited the proliferation, migration and invasion of adenomyotic epithelial cells, where miR-30c-5p knockdown had an opposite effect. Furthermore, we confirmed mitogen-activated protein kinase 1 (MAPK1) was one of the direct targets of miR-30c-5p, indicating its important role in miR-30c-5p-mediated suppression of proliferation, invasion and migration in adenomyotic epithelial cells. This study showed that the interaction of miR-30c-5p with MAPK1 can regulate the proliferation, invasion and migration in adenomyotic epithelial cells.

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.

Selective intrauterine growth restriction (sIUGR) in monochorionic twin pregnancies is associated with greater morbidity and mortality for both fetuses when compared to singleton and dichorionic pregnancies. This retrospective cohort study aimed to assess the perinatal outcomes of monochorionic twin pregnancies affected by this disorder and conducted expectantly, by analyzing the results according to the end-diastolic flow in the umbilical artery Doppler of the smaller twin (type I: persistently forward/type II: persistently absent or reversed/type III: intermittently absent or reversed). Seventy-five monochorionic diamniotic twin pregnancies with sIUGR were included in this study. sIUGR was defined by estimated fetal weight below the 3rd centile for gestational age, or below the 10th centile, when associated with at least one of the following three criteria: abdominal circumference below the 10th percentile, umbilical artery pulsatility index of the smaller twin above the 95th percentile, or estimated fetal weight discordance of 25% or more. Perinatal outcomes were analyzed from the prenatal period to hospital discharge and included perinatal death, neurological injury, retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), and sepsis. The mortality rate was 1.33% in this cohort. The overall morbidity rate was lower in type I twin pregnancies. In conclusion, this study shows that sIUGR type I has lower morbidity than types II and III in expectant management.

We evaluated the outcomes and adverse events after fetoscopic laser surgery (FLS) for twin–twin transfusion syndrome (TTTS) using the Solomon technique in comparison to the selective technique. A retrospective analysis of a single-center consecutive cohort of FLS-treated TTTS using the selective (January 2010 to July 2014) and Solomon (August 2014 to December 2017) techniques was performed. Among 395 cases, 227 underwent selective coagulation and 168 underwent the Solomon technique. The incidence rates of recurrent TTTS (Solomon vs. selective: 0% vs. .9%, p = .510) and twin anemia–polycythemia sequence (.6% vs. .4%, p = .670) were very low in both groups. The incidence rates of placental abruption (Solomon vs. selective: 10.7% vs. 3.5%, p = .007) and preterm premature rupture of the membranes (pPROM) with subsequent delivery before 32 weeks (20.2% vs. 7.1%, p < .001) were higher in the Solomon group. The median birth recipient weight was significantly smaller in the Solomon group (1790 g vs. 1933 g, p = .049). The rate of survival of at least one twin was significantly higher in the Solomon group (98.2% vs. 93.8%, p = .046). The Solomon technique and total laser energy were significant risk factors for pPROM (odds ratio: 2.64, 1.07, 95% CI [1.32, 5.28], [1.01, 1.13], p = .006, p = .014, respectively). These findings suggest that the Solomon technique led to superior survival outcomes but increased risks of placental abruption, pPROM and fetal growth impairment. Total laser energy was associated with the occurrence of pPROM. Close attention to adverse events is required for perinatal management after FLS to treat TTTS using the Solomon technique.

Modern reproductive technology and revisions of conventional family structures have yielded a curious array of twin-like sibships. Many of these pairings pose the same rearing questions and educational issues for parents and teachers as do ordinary monozygotic and dizygotic twins. This article considers how we classify these sibships, given the important implications for the pair members, their families, their friends and the professionals who care for them. Next, reviews of research on twins’ birth weight and brain development, twinning and vocabulary knowledge, fetal loss in twin pregnancy and twin-family Olympic medal winners are presented. The final topic covers recent media attention to young twin soldiers, a twin-run laundry, a male-female pair’s political differences, a twin-based graphic novel and twin sisters’ deliveries.