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Hereditary motor and sensory neuropathy with agenesis of the corpus callosum (HMSN/ACC) is a rare autosomal recessive condition characterised by early-onset severe progressive neuropathy, variable degrees of ACC and cognitive impairment. Mutations in

Background: Findings of reward disturbances in unaffected relatives of patients with schizophrenia suggest reward disturbances as an endophenotype for schizophrenia. Twin studies, where 1 twin has been diagnosed with a schizophrenia spectrum disorder, can further explore this. Methods: We used Danish registries to identify twin pairs with at least 1 twin having a schizophrenia spectrum disorder diagnosis and control twin pairs matched on age, sex, and zygosity. The analyses included data from 34 unaffected co-twins (16 females), 42 probands with schizophrenia spectrum disorder (17 females), and 83 control twins (42 females). Participants performed a modified incentive delay task during functional magnetic resonance imaging. Whole-brain group differences were analyzed by performing comparisons between co-twins and control twins. Correlations with cognitive flexibility were tested. Results: Compared with control twins, co-twins showed no differences in striatal regions, but increased signal in the dorsolateral prefrontal cortex (DLPFC) during missed target contrast was observed. In co-twins, increased DLPFC signal was associated with lower intra-extra dimensional set-shifting scores indicative of higher cognitive flexibility. Conclusions: Unaffected co-twins did not have decreased striatal activity during anticipation as previously reported for patients with schizophrenia. Instead, they showed increased activity in the DLPFC during evaluation of missed target contrast, which correlated with their level of cognitive flexibility. Unaffected co-twins had no diagnosis at a mean age of 40 years. This could indicate that greater cognitive flexibility and increased activity in the right DLPFC during processing of unexpected negative outcome represents a compensatory resilience mechanism in predisposed twins.

Major depressive disorder (MDD) is a highly prevalent psychiatric condition characterised by a heterogeneous clinical presentation and an estimated twin-based heritability of ~40-50 %. Different clinical MDD subtypes might partly reflect distinctive underlying genetics. This study aims to investigate if polygenic risk scores (PRSs) for different psychiatric disorders, personality traits, and substance use-related traits may be associated with different clinical subtypes of MDD (i.e., MDD with melancholic or psychotic features), higher symptom severity, or different clusters of depressive symptoms (i.e., sadness symptoms, typical neurovegetative symptoms, detachment symptoms, and negative thoughts).The target sample included 1149 patients with MDD, recruited by the European Group for the Study of Resistant Depression. PRSs for 25 psychiatric disorders and traits were computed based on the most recent publicly available summary statistics of the largest genome-wide association studies. PRSs were then used as predictors in regression models, adjusting for age, sex, population stratification, and recruitment sites.Patients with MDD having higher PRS for MDD and loneliness were more likely to exhibit melancholic features of MDD (p = 0.0009 and p = 0.005, respectively). Moreover, patients with higher PRS for alcohol intake and post-traumatic stress disorder were more likely to experience greater typical neurovegetative symptoms (p = 0.0012 and p = 0.0045, respectively).The proportion of phenotypic variance explained by the PRSs was limited.This study suggests that melancholic features and typical neurovegetative symptoms of MDD may show distinctive underlying genetics. Our findings provide a new contribution to the understanding of the genetic heterogeneity of MDD.

In twin pregnancies, amnionicity and chorionicity are crucial as they strongly determine prenatal and perinatal management. First trimester ultrasound allows a highly reliable diagnosis of amnionicity and chorionicity, making it an internationally accepted standard in antenatal care. However, in rare cases, amnionicity can change from diamniotic to monoamniotic throughout pregnancy, substantially impacting perinatal management. We report the case of a confirmed monochorionic diamniotic twin pregnancy with a diagnosis of spontaneous septostomy of the dividing membrane (SSDM) at 28 weeks of gestation, resulting in a pseudomonoamniotic pregnancy. Even though SSDM is a rare condition and its sonographic diagnosis might be challenging, it should be considered if, in a known diamniotic pregnancy, there is a sudden failure to visualise the intertwin membrane truly separating both twins.

Given the well-documented importance of counterproductive workplace behavior and organizational citizenship behavior (together nontask performance), it is important to clarify the degree to which these behaviors are attributable to organizational climate versus preexisting individual differences. Such clarification informs where these behaviors stem from, and consequently has practical implications for organizations (e.g., guiding prioritization of selection criteria). We investigated familial resemblance for nontask performance among twins, nontwin and adoptive siblings, parents and offspring, and midlife and late-life couples drawn from two, large-scale studies: the Minnesota Twin Family Study and the Sibling Interaction Behavior Study. Similarity among family members’ (e.g., parents–offspring, siblings) engagement in nontask performance was assessed to estimate the degree to which preexisting individual differences (i.e., genetic variability) and the environment (i.e., environmentality) accounted for variation in counterproductive and citizenship behavior. We found that degree of familial resemblance for nontask performance increased with increasing genetic relationship. Nonetheless, genetically identical individuals correlated only moderately in their workplace behavior (r = .29–.40), highlighting the importance of environmental differences. Notably, family members were more similar in their counterproductive than citizenship behavior, suggesting citizenship behavior is comparatively more environmentally influenced. Spouse/partner similarity for nontask behavior was modest and did not vary between midlife and late-life couples, suggesting spousal influence on nontask performance is limited. These findings offer insight to organizations regarding the degree of nature (individual differences) and nurture (including organizational factors) influences on nontask performance, which has implications for the selection of interventions (e.g., relative value of applicant selection or incumbent interventions).

ObjectiveTwins account for approximately 1 in 30 live births in the United States. However, there are limited clinical experience studies published in noninvasive prenatal testing (NIPT) for detecting aneuploidies in twins. This study reports the performance of an SNP-based NIPT in the largest cohort with known outcomes for high-risk aneuploidy results.MethodThis is a retrospective analysis of 18,984 results from commercial single-nucleotide polymorphism (SNP)-based NIPT tests performed in twins between October 2, 2017 and December 31, 2019. Follow-up for all 211 high-risk cases was solicited.ResultsFollow-up outcomes were obtained in 105 cases. Positive predictive values (PPVs) for high-risk results were 88.7% (63/71, 95% Confidence Interval [CI]: 79.0%-95.0%) for trisomy 21% and 72.7% (8/11, 95% CI: 39.0%-94.0%) for trisomy 18. The results were stratified into monozygotic (MZ) and dizygotic (DZ). The PPVs in MZ were 100% for both trisomy 21 (4/4, 95% CI: 40%-100%) and trisomy 18 (1/1, 95% CI: 2.5%-100%). No trisomy 13 cases were detected in the MZ group. The PPVsin DZ were 88.1% (59/67, 95% CI: 77.8%-94.7%), 70.0% (7/10, 95% CI: 34.8%-93.3%), and 66.7% (2/3, 95% CI: 9.4%-99.2%) for trisomy 21, trisomy 18, and trisomy 13, respectively.ConclusionThe performance of SNP-based NIPT in this large twin cohort was comparable to previously reported twin NIPT studies. SNP-based NIPT allows for zygosity-based PPV assessment.

Because deficits in self-regulation (SR) are core features of many diverse psychological disorders, SR may constitute one of many dimensions that underlie shared variance across diagnostic boundaries (e.g., the p factor, a dimension reflecting shared variance across multiple psychological disorders). SR definitions encompass constructs mapping onto different theoretical traditions and different measurement approaches, however. Two SR operationalizations, executive functioning and conscientiousness, are often used interchangeably despite their low empirical associations-a "jingle" fallacy that pervades much of the research on SR-psychopathology relationships. In a population-based sample of 1,219 twins and multiples from the Texas Twin Project (Mage = 10.60, SDage = 1.76), with a comprehensive battery of measures, we aimed to clarify how these often-muddled aspects of SR relate to individual differences in psychopathology, and whether links between them are accounted for by overlapping genetic and environmental factors. The p factor and an Attention Problems-specific factor were associated with lower executive functioning and conscientiousness. Executive functioning shared a small amount of genetic variance with p above and beyond conscientiousness, whereas conscientiousness shared substantial genetic variance with p independently of genetic variance accounted for by executive functioning. Conversely, the Attention Problems-specific factor was strongly genetically associated with executive functioning independently of genetic variance accounted for by conscientiousness. Results support the notion that SR and psychopathology, broadly conceived, may exist on overlapping spectra, but this overlap varies across conceptualizations of SR and the level of specificity at which psychopathology is assessed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Observational epidemiological analyses demonstrated a decreased risk of death and severe morbidity associated with caesarean delivery at term but an increased risk at preterm gestational age. A multicentre international randomized controlled compared planned caesarean section with vaginal birth and observed no difference in outcome; however, the trial included preterm and term births in approximately similar proportions. A subsequent re-analysis of the trial demonstrated that planned caesarean section was associated with an increased risk of adverse neonatal outcome at preterm gestational ages, but reduced the risk of perinatal complications at term, consistent with the epidemiological studies. Hence, decision-making around mode of delivery for twins should recommend against routine caesarean delivery preterm. At term, the balance of risks and benefits will vary according to the mother's prioritization of avoiding intervention, her attitude to managing the risks of uncommon but potentially severe adverse events, and her plans and potential for future pregnancies.

Noncognitive factors have gained attention in recent years as potential intervention targets for academic achievement improvement in students. Two notable facets, intelligence mindset and grit, have been of particular interest. Both have been shown to consistently improve educational outcomes, although little work has focused on reading ability. As such, we examined the relation between both grit and mindset on current, future, and change in reading comprehension ability in a twin sample. We used data from 422 twin pairs (171 monozygotic pairs, 251 dizygotic pairs) drawn from the Florida Twin Project on Reading, Behavior and Environment (Taylor et al., 2019). The racial composition of the sample included 1.00% American Indian or Alaska Native, 2.25% Asian, 13.25% Black or African American, 22.63% Hispanic, 1.00% Native Hawaiian or Other Pacific Islander, 56.13% White, and 3.75% more than 1 race. The household income of the sample at time 1 was 16.15% below $25,000, 18.06% $25,000-49,999, 36.34% $50,000-99,999, and 29.45% $100,000 or more and closely align with the overall composition reported for the state of Florida (United States Census Bureau, 2021). Twins were on average 13 years old when the questionnaire and first reading ability measure were collected, and on average 15 years old when the second reading ability measure was collected. Weak and moderate positive correlations were found between both mindset and grit and with each reading ability score and neither were significantly related to change in reading ability. Twin modeling suggested little to no common genetic or environmental influences between mindset and grit to reading ability. In total, our results do not lend support to the notion of mindset or grit being a mechanism of change for reading ability. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The effect of systemic hormone therapy (HT) on dementia risk is unclear. Our aim was to investigate the association between HT and dementia.This register-based study consists of a nested case-control study and a co-twin control design, which controls for familial confounding, including shared genetics.Through Danish national registries from 1995 to 2011, we identified: a) 2700 female singletons with incident dementia and 13,492 matched controls; b) 288 female twins with incident dementia and co-twins without dementia. Data on HT and education were retrieved, and analyses were performed using conditional logistic regression and McNemar's χThe odds ratio (OR) for the association between systemic HT and dementia was 1.05, 95% CI = [0.93-1.19] in singletons and 2.10, 95% CI = [0.99-4.46] in twins. A statistically significant association was found for systemic HT before 2003 in both populations, with an OR of 1.14, 95% CI = [1.01-1.28] in singletons and an OR of 2.20, 95% CI = [1.04-4.65] in twins.Using Danish nationwide registries and controlling for education and for familial factors in a subsample, systemic HT was found to be associated with increased dementia risk if used before 2003, when HT was more commonly prescribed.

Background: In recent decades there has been a major increase in multiple birth rates, and the rate of twining vary from 6-9 per thousand life births to 20 per thousand live births across differ-ent areas of the world. Many studies have demonstrated higher neonatal and perinatal mortality and morbidity rates in twin deliveries compared to singleton births. This study was aimed to com-pare the outcomes of preterm twins and preterm singletons.Methods: A prospective, observational multicenter study was conducted from July 2016 to May 2018 in five tertiary hospitals in Ethiopia. All preterm, liveborn infants born at or transferred at less than 7 days of life to one of the study hospitals with an estimated gestational age below 37 weeks were included.Results: A total of 3,703 preterm neonates admitted to participating neonatal intensive care units were included in the study, of which 1171(31.6%) were twins. After adjusting for birth weight and gestational age, the mortality rate for preterm singletons of 31.0% was higher than the mortality rate for preterm twins of 24.8%, which was statistically significant (p-value = 0.001), OR of 1.37 (95% CI: 1.15 to 1.64). The study also identified an inverse relationship between birth weight and gestational age, and mortality. Male singletons were more likely to die than male twins (440 (32.4%) vs. 141 (23.4%); AOR 1.56 (95% CI: 1.22, 1.99); p=0.001)Conclusion: Our study showed that the mortality of a singleton preterm infant was significantly higher than the mortality of a preterm twin infant

The unique sources of artistic inspiration and talent of twin artists are examined. The professional literature is rich with twin studies of creativity, but lacking when it comes to specific artistic domains — for example, painting and sculpting. The section that follows provides reviews of current research on ethnic and racial factors affecting type of twin delivery, pregnancy outcomes when twins are conceived naturally or with reproductive assistance, the effects of intrauterine growth discordance on the timing of twin delivery, and three-dimensional (3D) assessment of twins’ facial resemblance. The final section summarizes information about twins in the media. The stories include twins distinguished for both baseball playing and physical injuries, twins who reached the National College Athletic Association’s Elite 8, a twin pair’s grave and epitaph, a mother who conceived twins three times in 2 years, twins in the Hockey Hall of Fame, and a set of superfetated twins.

Much debate has concerned the separability of executive function abilities and intelligence, with some evidence that the 2 constructs are genetically indistinguishable in children and adolescents but phenotypically and genetically distinct in older adolescents and adults. The current study leveraged data from twin and adoption studies to examine executive function's genetic structure in adulthood (

The high-affinity copper transporter CTR1 is encoded by CTR1 (SLC31A1), a gene locus for which no detailed genotype–phenotype correlations have previously been reported. We describe identical twin male infants homozygous for a novel missense variant NM_001859.4:c.284 G > A (p.Arg95His) in CTR1 with a distinctive autosomal recessive syndrome of infantile seizures and neurodegeneration, consistent with profound central nervous system copper deficiency. We used clinical, biochemical and molecular methods to delineate the first recognized examples of human CTR1 deficiency. These included clinical phenotyping, brain imaging, assays for copper, cytochrome c oxidase (CCO), and mitochondrial respiration, western blotting, cell transfection experiments, confocal and electron microscopy, protein structure modeling and fetal brain and cerebral organoid CTR1 transcriptome analyses. Comparison with two other critical mediators of cellular copper homeostasis, ATP7A and ATP7B, genes associated with Menkes disease and Wilson disease, respectively, revealed that expression of CTR1 was highest. Transcriptome analyses identified excitatory neurons and radial glia as brain cell types particularly enriched for copper transporter transcripts. We also assessed the effects of Copper Histidinate in the patients’ cultured cells and in the patients, under a formal clinical protocol. Treatment normalized CCO activity and enhanced mitochondrial respiration in vitro, and was associated with modest clinical improvements. In combination with present and prior studies, these infants’ clinical, biochemical and molecular phenotypes establish the impact of this novel variant on copper metabolism and cellular homeostasis and illuminate a crucial role for CTR1 in human brain development. CTR1 deficiency represents a newly defined inherited disorder of brain copper metabolism.

Previous studies have demonstrated associations between substance use and reduced educational attainment; however, many were unable to account for potential confounding factors like genetics and the rearing environment. In the few studies that controlled for these factors, the substances assessed were limited to alcohol, cannabis, and tobacco. To address these limitations, we examined the relationship between adolescent use of seven kinds of substances, the number of additional substances used, and high school noncompletion within a large sample of Australian twins.A series of two-level generalized mixed effects logistic regressions were conducted to examine associations between adolescent substance use and high school noncompletion.Australia.A total of 9579 adult Australian twins from two cohorts of the Australian Twin Registry.Assessments of high school completion, childhood major depression, conduct disorder symptoms, substance use initiation, demographics, and parental educational attainment using the Australian version of the Semi-Structured Assessment for the Genetics of Alcoholism.There were unique within-twin-pair effects of use of sedatives (odds ratio [OR] = 22.39 [95% confidence interval (CI) = 1.18-423.48]) and inhalants/solvents (OR = 10.46 [95% CI = 1.30-84.16]) on high school noncompletion. The number of substances used in adolescence was strongly associated with high school noncompletion across all discordant twin models (ORs from 1.50-2.32, Ps0.03).In Australia, adolescent substance use appears to be associated with early school dropout, with the effects of any given substance largely because of the confounding factors of parental education, childhood conduct disorder symptoms, and use of other substances. Sedatives and inhalants/solvents have effects on high school noncompletion that cannot be explained by polysubstance use or familial factors.

Background: Multiple pregnancy is a known predisposing factor for sagittal suture synostosis, and intrauterine constraint has been suggested as a potential cause. This study evaluates prenatal images of single and multiple pregnancies of children with sagittal suture synostosis to assess the possible pathogenesis. Materials and Methods: Prenatal ultrasound data of scaphocephaly twins treated at Erasmus MC was retrieved retrospectively. The head circumference, cephalic index (CI), and biparietal diameter (BPD) were analyzed. Data were compared with the nonaffected sibling, singletons with scaphocephaly, and to general fetal growth reference values. Results: Data of 8 twin pregnancies with 10 cases of scaphocephaly was gathered. For the head circumference no difference was found between affected fetuses and reference values throughout pregnancy. For the BPD a reduced growth was found, compared with control values. The growth curve for the CI of the affected twins is lower from the start and declines over time. When comparing affected fetuses to nonaffected fetuses, the same differences for the BPD and CI were found as compared with controls. No differences in growth parameters were found between the nonaffected siblings and reference values, nor between the affected scaphocephaly twins and singletons with scaphocephaly. Conclusions: Scaphocephaly in twin pregnancy develops early on in pregnancy, similar to singleton pregnancy, making the theory of constraint as a cause less likely. The development of scaphocephaly in twins is likely to be attributed to the same disturbed developmental processes in suture development as in singletons, and not to mechanical constraint.

V tej študiji smo preučili morfološke, kemijske in strukturne podrobnosti tetraedrsko oblikovanih kristalov pirita iz rudnika Jean Baptiste v Lavrionu. Pirit se pojavlja v treh generacijah. Prvo predstavljajo tetraedrski levo oziroma desno sučni kristali z najnižjo kubično 23 simetrijo. V tej generaciji so dvojčki z višjo kubično m_3 in heksagonalno 6 simetrijo. Vsi kristali druge generacije so že primarno zdvojčeni do kubične_4m3 simetrije. Nekateri pa se dvojčijo še naprej dokler ne dosežejo najvišje kubične m_3m ali heksagonalne 6mm simetrije. Kristali tretje generacije neorientirano prekrivajo kristale druge generacije. Kemijska analiza potrjuje kemijsko čist pirit, monokristalna rentgenska analiza kristalov prve in druge generacije pa za pirit značilno m_3 simetrijo. Očitno je torej, da morfološke oblike posameznih kristalov in dvojčkov kažejo na to, da imajo najnižjo kubično simetrijo, česar pa strukturna analiza ne potrjuje. Ta diskrepanca je lahko posledica spremenjenih pT pogojev in posledične transformacije prvotne strukture pirita s simetrijo 23 v sekundarno strukturo z m_3 simetrijo ali pa neoptimalnih pogojev pri določitvi strukture z rentgensko difrakcijo. V tej študiji smo preučili morfološke, kemijske in strukturne podrobnosti tetraedrsko oblikovanih kristalov pirita iz rudnika Jean Baptiste v Lavrionu. Pirit se pojavlja v treh generacijah. Prvo predstavljajo tetraedrski levo oziroma desno sučni kristali z najnižjo kubično 23 simetrijo. V tej generaciji so dvojčki z višjo kubično m_3 in heksagonalno 6 simetrijo. Vsi kristali druge generacije so že primarno zdvojčeni do kubične_4m3 simetrije. Nekateri pa se dvojčijo še naprej dokler ne dosežejo najvišje kubične m_3m ali heksagonalne 6mm simetrije. Kristali tretje generacije neorientirano prekrivajo kristale druge generacije. Kemijska analiza potrjuje kemijsko čist pirit, monokristalna rentgenska analiza kristalov prve in druge generacije pa za pirit značilno m_3 simetrijo. Očitno je torej, da morfološke oblike posameznih kristalov in dvojčkov kažejo na to, da imajo najnižjo kubično simetrijo, česar pa strukturna analiza ne potrjuje. Ta diskrepanca je lahko posledica spremenjenih pT pogojev in posledične transformacije prvotne strukture pirita s simetrijo 23 v sekundarno strukturo z m_3 simetrijo ali pa neoptimalnih pogojev pri določitvi strukture z rentgensko difrakcijo.

Study Objectives Digital technology use is associated with poor sleep quality in adolescence and young adulthood although research findings have been mixed. No studies have addressed the association between the two using a genetically informative twin design which could extend our understanding of the etiology of this relationship. This study aimed to test: (1) the association between adolescents’ perceived problematic use of digital technology and poor sleep quality, (2) whether the association between problematic use of technology and poor sleep quality remains after controlling for familial factors, and (3) genetic and environmental influences on the association between problematic use of technology and poor sleep quality. Methods Participants were 2232 study members (18-year-old twins) of the Environmental Risk (E-Risk) Longitudinal Twin Study. The sample was 48.9% male, 90% white, and 55.6% monozygotic. We conducted regression and twin difference analyses and fitted twin models. Results Twin differences for problematic use of technology were associated with differences for poor sleep quality in the whole sample (p < 0.001; B = 0.15) and also when we limited the analyses to identical twins only (p < 0.001; B = 0.21). We observed a substantial genetic correlation between problematic use of technology and sleep quality (rA = 0.31), whereas the environmental correlation was lower (rE = 0.16). Conclusions Adolescent reported problematic use of digital technology is associated with poor sleep quality—even after controlling for familial factors including genetic confounds. Our results suggest that the association between adolescents’ sleep and problematic digital technology use is not accounted for by shared genetic liability or familial factors but could reflect a causal association. This robust association needs to be examined in future research designed to test causal associations.

The hippocampus is a complex brain structure with key roles in cognitive and emotional processing and with subregion abnormalities associated with a range of disorders and psychopathologies. Here we combine data from two large independent young adult twin/sibling cohorts to obtain the most accurate estimates to date of genetic covariation between hippocampal subfield volumes and the hippocampus as a single volume. The combined sample included 2148 individuals, comprising 1073 individuals from 627 families (mean age = 22.3 years) from the Queensland Twin IMaging (QTIM) Study, and 1075 individuals from 454 families (mean age = 28.8 years) from the Human Connectome Project (HCP). Hippocampal subfields were segmented using FreeSurfer version 6.0 (CA4 and dentate gyrus were phenotypically and genetically indistinguishable and were summed to a single volume). Multivariate twin modeling was conducted in OpenMx to decompose variance into genetic and environmental sources. Bivariate analyses of hippocampal formation and each subfield volume showed that 10%–72% of subfield genetic variance was independent of the hippocampal formation, with greatest specificity found for the smaller volumes; for example, CA2/3 with 42% of genetic variance being independent of the hippocampus; fissure (63%); fimbria (72%); hippocampus-amygdala transition area (41%); parasubiculum (62%). In terms of genetic influence, whole hippocampal volume is a good proxy for the largest hippocampal subfields, but a poor substitute for the smaller subfields. Additive genetic sources accounted for 49%–77% of total variance for each of the subfields in the combined sample multivariate analysis. In addition, the multivariate analyses were sufficiently powered to identify common environmental influences (replicated in QTIM and HCP for the molecular layer and CA4/dentate gyrus, and accounting for 7%–16% of total variance for 8 of 10 subfields in the combined sample). This provides the clearest indication yet from a twin study that factors such as home environment may influence hippocampal volumes (albeit, with caveats).

To compare maternal cardiovascular indices at 19-23 weeks' gestation between twin and singleton pregnancies and assess the impact of chorionicity on these parameters.This was a prospective observational study in women with twin pregnancy attending for a hospital visit at 19 + 1 to 24 + 3 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history and maternal cardiovascular assessment. In a previous study of 4795 women with singleton pregnancies at 19-23 weeks' gestation, multivariable linear regression models were fitted between the various cardiovascular indices and elements of maternal characteristics and medical history. In this study, we calculated multiples of the median (MoM) and delta values according to the singleton models and assessed the distributional properties of these MoM and delta values in twin as compared with singleton pregnancies.The study population of 155 women with twin pregnancy included 86 dichorionic and 69 monochorionic cases. In general, there was a similar distribution of maternal cardiovascular indices in monochorionic and dichorionic twin pregnancies. In both types of twin pregnancy, compared with singleton pregnancy, there was an increase in isovolumetric relaxation time, left atrial area and myocardial performance index, and a decrease in mitral valve E/A. Left ventricular mass indexed for body surface area and relative wall thickness were also increased in twin compared with singleton pregnancy. The magnitude of the increase in left atrial area was greater in dichorionic compared with monochorionic pregnancies. Additionally, mitral valve E was decreased and left atrial volume was increased in dichorionic but not in monochorionic pregnancies, while isovolumetric contraction time was increased in monochorionic but not in dichorionic pregnancies. Left ventricular myocardial deformation was similar between twin and singleton pregnancies.In twin pregnancies at mid-gestation, maternal systolic and diastolic function is reduced when compared with singletons. The patterns of cardiovascular adaptation are similar between monochorionic and dichorionic pregnancies and resemble those reported in uncomplicated singleton pregnancy later in gestation. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Twin reversed arterial perfusion (TRAP) sequence is a rare anomaly in 1% of monochorionic twin pregnancies. Few TRAP sequence cases have a rudimentary heart with cardiac motion in the acardiac twins. Herein, we investigated the venous Doppler waveform in two cases of TRAP sequence with a rudimentary heart with cardiac motion in the acardiac twin. Although both cases had veno-venous anastomoses, the venous Doppler waveforms of the umbilical vein differed. A comparison of the characteristics of the cases indicated that the existence of a ductus venosus, or greater heart pulse power, in the acardiac twin might impact the venous Doppler waveform in the pump twin.

Congenital anomalies of the infrarenal inferior vena cava (IVC) are well described in adult life, however, little information exists on their associations in fetal life. Here, we describe a case of a monochorionic diamniotic (MCDA) twin pregnancy complicated by selective fetal growth restriction (sFGR) with an incidental finding of a double IVC in one child. In fetal life, variants of the infrarenal IVC are strongly associated with heart defects, which might suggest haemodynamic alterations or genetic causes, even more so in our case with MCDA twins complicated by sFGR.

In the modern world, the reduction of maternal and perinatal morbidity and mortality remain as the main problems. One of the causes of perinatal complications is the pathology of the umbilical cord. The purpose of the study was to determine the relationship between abnormal cord attachment and fetal discordant growth in twin pregnancies. In 73 (46.8%) cases were found marginal attachment of the umbilical cord, in 26 (14%) cases were sheathing attachment and normal attachment occurred in 87 (46.8%) cases. The relationship between abnormal attachment of the umbilical cord with the type of placentation was determined. In women with MCh and DCh type, marginal attachment was detected in 28 (41.2%) and 45 (38.1%), sheath attachment in 14 (20.6%) and 12 (10.2%) cases, respectively. The relationship between the discrepancy between body weight at birth and the type of umbilical cord attachment was determined. There was a high percentage of discordance by birth weight >25% in 23.6% in pregnancies with sheath attachment of the umbilical cord. Determination of chorionism, amniogenecity and detection of placental abnormalities are key issues for adequate management of multiple pregnancies.

Background: There is some evidence that autism spectrum disorder (ASD) frequently co-occurs with immune-mediated conditions including asthma. We aimed to explore the familial co-aggregation of ASD and asthma using different genetically informed designs. Methods: We first examined familial co-aggregation of asthma and ASD in individuals born in Sweden from 1992 to 2007 (n = 1 569 944), including their full- and half-siblings (n = 1 704 388 and 356 544 pairs) and full cousins (n = 3 921 890 pairs), identified using Swedish register data. We then applied quantitative genetic modeling to siblings (n = 620 994 pairs) and twins who participated in the Child and Adolescent Twin Study in Sweden (n = 15 963 pairs) to estimate the contribution of genetic and environmental factors to the co-aggregation. Finally, we estimated genetic correlations between traits using linkage disequilibrium score regression (LDSC). Results: We observed a within-individual association [adjusted odds ratio (OR) 1.33, 95% confidence interval (CI) 1.28-1.37] and familial co-aggregation between asthma and ASD, and the magnitude of the associations decreased as the degree of relatedness decreased (full-siblings: OR 1.44, 95% CI 1.38-1.50, maternal half-siblings: OR 1.28, 95% CI 1.18-1.39, paternal half-siblings: OR 1.05, 95% CI 0.96-1.15, full cousins: OR 1.06, 95% CI 1.03-1.09), suggesting shared familial liability. Quantitative genetic models estimated statistically significant genetic correlations between ASD traits and asthma. Using the LDSC approach, we did not find statistically significant genetic correlations between asthma and ASD (coefficients between -0.09 and 0.12). Conclusions: Using different genetically informed designs, we found some evidence of familial co-aggregation between asthma and ASD, suggesting the weak association between these disorders was influenced by shared genetics.

The occurrence of CAD is strongly affected by genetic, epigenetic and environmental factors. Currently, a growing yet heterogeneous body of evidence reports CAD development in identical twins; however, no systematic approach has been attempted so far to gather and quantify the existing evidence. The aim of this systematic review will be to cover this gap of knowledge through systematically gathering the existing data. A systematic literature review will be conducted by searching for original studies in PubMed, WebOfScience and Scopus databases to identify every study reporting the incidence of CAD in twin pairs according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and predetermined eligibility criteria.

Pain is a multidimensional experience that emerges from interactions among sensory, affective, and cognitive processes in the brain (Melzack, 2001). Epidemiological studies of chronic pain find a relationship between low income and chronic pain prevalence across the globe (Grol-Prokopczyk, 2017; Reddan, 2021), suggesting that experiences of economic deprivation can influence an individual's pain experience. However, this is a largely unexplored area of research in basic pain neuroscience. Here we investigate whether an individual's Area Deprivation Index (ADI; Kind & Buckingham, 2018), that is, the wealth of their neighborhood of residence, influences pain ratings and pain-evoked brain activity. We expect that living in deprivation will increase the salience of nociceptive information, because injuries in deprived environments are more costly than injuries in enriched environments. We expect this increase in saliency to result in higher pain self-reports. This study is a novel analysis of the PainGen Twin data set (https://osf.io/unh7f). We subselect twin samples where one twin lives in an area with a high ADI but their twin lives in an area with low ADI. In this way, we get to control for may other person-level factors that can influence pain independent of ADI.

Podalic version and breech extraction require high obstetrical expertise. Identifying fetal extremities is the first crucial step for trainees. When this skill is not polished enough, it increases the inter-twin delivery interval and can even jeopardize the whole manoeuver.We present a model for simulating and training this specific skill, with obstetrical mannequin, and 3D printed hands and feet. Five feet and five hands (five rights and five lefts of each one) were printed in 3D after initial ultrasound acquisition of a near term fetus. Each foot and hand, was individually set in a condom filled with 100 cc of water and closed with a knot. A Sophie's Mum Birth Simulator Version 4.0 de MODEL-med was placed on the edge of the table. Each hand and foot was inserted into the pelvic mannequin. An evaluation of the students' skills using this model was performed. A significant reduction of the global mean to extract the first foot and all the feet was noticed at three month of interval.This model is an option to train and assess a crucial skill for version and breech extraction.

To compare fetomaternal outcomes between GDM pregnant women with twin versus singleton pregnancies and then between women with GDM versus non-GDM twin pregnancies.We performed a retrospective study including GDM pregnant women with both twin and singleton pregnancies followed in our tertiary center between 2011 and 2018. The fetomaternal characteristics of each group were compared. We then compared women with GDM twin pregnancy followed at our institution between 2011 and 2018 to non-GDM twin pregnant women giving childbirth in 2018.A total of 1127 GDM pregnant women were evaluated: 42 with twin pregnancy and 1085 with singleton pregnancy. Preeclampsia (14.3% vs. 3.3%, p 0.001) and cesarean delivery (76.2% vs. 36.9%, p 0.001) were more frequent among women with twin pregnancy. Neonatal morbidity was also more common among neonates delivered from twin pregnant women, including preterm labor (73.8% vs. 7.8%, p 0.001), hypoglycemia (6% vs. 4.8%, p = 0.043), hyperbilirubinemia (33.3% vs. 9.0%, p 0.001), RDS (28.6% vs. 2.7%, p 0.001), admission in NICU (32.1% vs. 4.5%, p 0.001) and SGA (19.0% vs. 11.0%, p = 0.001). Overall there were no significant differences in fetomaternal morbidity parameters between GDM (n = 42) versus non-GDM (n = 83) twin pregnancies, although SGA infants were more frequent in the latter group (33.9% vs. 19.0%, p = 0.014).In GDM pregnant women, twin pregnancy seems to be associated with an increased prevalence of neonatal morbidity when compared to singleton pregnancy. On the other hand, in twin pregnancy, diagnosis of GDM does not seem to be associated with poorer fetomaternal outcomes. GDM seems to be protective for the occurrence of SGA neonates in twin pregnancies.

Beckwith-Wiedemann Syndrome is a congenital disease that is rare and has low prevalence worldwide. It presents classically with features of macroglossia, abdominal wall defects (omphalocele), and macrosomia at birth. Other typical manifestations include facial nevus simplex, ear lobe abnormalities (creases and/or pits), transient hypoglycemia, and renal abnormalities seen on ultrasound. We report a case of a female preterm infant of twin gestation presenting at our level 4 hospital’s newborn unit with typical features of the syndrome. We aimed to create further awareness on the diagnosis in secondary health institutions and management of common features and complications of the syndrome. There is a paucity of pictorial evidence of morphology and literature related to the syndrome in an African child and this case report aims to improve that. No case has been previously reported in the Kenyan setting.

Medically-indicated deliveries are common in twin pregnancies given the increased risk of various obstetric complications in twin compared to singleton pregnancies, mainly hypertensive disorders of pregnancy and foetal growth restriction. Due to the unique characteristics of twin pregnancies, the success rates and safety of labour induction may be different than in singleton pregnancies. However, while there are abundant data regarding induction of labour in singleton pregnancies, the efficacy and safety of labour induction in twin pregnancies have been far less studied. In the current manuscript we summarize available data on various aspects of labour induction in twin pregnancies including incidence, success rate, prognostic factors, safety and methods for labour induction in twins. This information may assist healthcare providers in counselling patients with twin pregnancies when labour induction is indicated.

Twins involve a higher risk of perinatal complications compared to singletons. We compared the risk of under five mortality between twins and singletons among late preterm and term births. The national birth data of South Korea pertaining to the years 2010-2014 linked with the mortality record of children aged under 5 years in 2010-2019 was analyzed. The final study population was 2,199,632 singletons and 62,351 twins. We conducted a survival analysis of under-five mortality with adjustment for neonatal and familial factors. Overall under-five mortality rates during the study period were 3.6 and 2.0 for twins and singletons, respectively. Although the unadjusted overall under-five mortality was higher in twins (hazard ratio [HR] = 1.80, 95% confidence interval [CI]: 1.57, 2.06, overall risk), twin birth was associated with comparable or lower risk (HR = 0.70, 95% CI: 0.58, 0.85, overall; 0.70, 95% CI: 0.56, 0.87, excluding neonatal mortality; 0.59, 95% CI: 0.40, 0.86, excluding infant mortality) after controlling for both neonatal and familial factors. Twins born at a gestational age of 34-35 weeks showed a generally lower risk of under-five mortality than their singleton counterparts, regardless of model specification.Conclusion: Among late preterm and term birth, under-5-year mortalities for twins were lower than singleton births when adjusted for neonatal and familial risk factors. This highlights the differential implication of gestational age at birth between twin and singleton in the child mortality.

Tau accumulation starts during the preclinical phase of Alzheimer’s disease and is closely associated with cognitive decline. For preventive purposes, it is important to identify factors associated with tau accumulation and spread. Studying genetically identical twin-pairs may give insight into genetic and environmental contributions to tau pathology, as similarities in identical twin-pairs largely result from genetic factors, while differences in identical twin-pairs can largely be attributed to non-shared, environmental factors. This study aimed to examine similarities and dissimilarities in a cohort of genetically identical older twin-pairs in (i) tau load; and (ii) spatial distribution of tau, measured with 18F-flortaucipir PET. We selected 78 genetically identical twins (39 pairs; average age 73 ± 6 years), enriched for amyloid-β pathology and APOE ε4 carriership, who underwent dynamic 18F-flortaucipir PET. We extracted binding potentials (BPND) in entorhinal, temporal, widespread neocortical and global regions, and examined within-pair similarities in BPND using age and sex corrected intra-class correlations. Furthermore, we tested whether twin-pairs showed a more similar spatial 18F-flortaucipir distribution compared to non-twin pairs, and whether the participant’s co-twin could be identified solely based on the spatial 18F-flortaucipir distribution. Last, we explored whether environmental (e.g. physical activity, obesity) factors could explain observed differences in twins of a pair in 18F-flortaucipir BPND. On visual inspection, Alzheimer’s disease-like 18F-flortaucipir PET patterns were observed, and although we mainly identified similarities in twin-pairs, some pairs showed strong dissimilarities. 18F-flortaucipir BPND was correlated in twins in the entorhinal (r = 0.40; P = 0.01), neocortical (r = 0.59; P < 0.01) and global (r = 0.56; P < 0.01) regions, but not in the temporal region (r = 0.20; P = 0.10). The 18F-flortaucipir distribution pattern was significantly more similar between twins of the same pair [mean r = 0.27; standard deviation (SD) = 0.09] than between non-twin pairings of participants (mean r = 0.01; SD = 0.10) (P < 0.01), also after correcting for proxies of off-target binding. Based on the spatial 18F-flortaucipir distribution, we could identify with an accuracy of 86% which twins belonged to the same pair. Finally, within-pair differences in 18F-flortaucipir BPND were associated with within-pair differences in depressive symptoms (0.37 < β < 0.56), physical activity (−0.41 < β < −0.42) and social activity (−0.32 < β < −0.36) (all P < 0.05). Overall, identical twin-pairs were comparable in tau load and spatial distribution, highlighting the important role of genetic factors in the accumulation and spreading of tau pathology. Considering also the presence of dissimilarities in tau pathology in identical twin-pairs, our results additionally support a role for (potentially modifiable) environmental factors in the onset of Alzheimer’s disease pathological processes, which may be of interest for future prevention strategies.

Because longitudinal studies of aging typically lack cognitive data from earlier ages, it is unclear how general cognitive ability (GCA) changes throughout the life course. In 1173 Vietnam Era Twin Study of Aging (VETSA) participants, we assessed young adult GCA at average age 20 and current GCA at 3 VETSA assessments beginning at average age 56. The same GCA index was used throughout. Higher young adult GCA and better GCA maintenance were associated with stronger specific cognitive abilities from age 51 to 73. Given equivalent GCA at age 56, individuals who had higher age 20 GCA outperformed those whose GCA remained stable in terms of memory, executive function, and working memory abilities from age 51 to 73. Thus, paradoxically, despite poorer maintenance of GCA, high young adult GCA still conferred benefits. Advanced predicted brain age and the combination of elevated vascular burden and APOE-ε4 status were associated with poorer maintenance of GCA. These findings highlight the importance of distinguishing between peak and current GCA for greater understanding of cognitive aging.

Theories in sociology argue that family background and individual experiences shape cultural tastes and participation. Yet, we do not know the relative importance of each explanation or the extent to which family background operates via shared genes or shared environments. In this article, we use new data on same-sex monozygotic and dizygotic twins from Denmark to estimate the total impact of family background (genetic and environmental) and individual experiences on highbrow and lowbrow tastes and participation and on omnivorousness in music and reading. We find that family background explains more than half of the total variance in cultural tastes and participation and in omnivorousness. Moreover, family background operates mainly via shared genes, with shared environments shaping cultural tastes to some extent, but not cultural participation. Our findings support theories claiming that family background is instrumental in shaping cultural tastes and participation but highlight the relevance of distinguishing genetic and environmental aspects of family background.

Objective To investigate differences in the heritability of skeletodental characteristics between twin pairs with skeletal Class I and Class II malocclusions. Methods Forty Korean adult twin pairs were divided into Class I (C-I) group (0° ≤ angle between point A, nasion, and point B [ANB]) ≤ 4°; mean age, 40.7 years) and Class II (C-II) group (ANB > 4°; mean age, 43.0 years). Each group comprised 14 monozygotic and 6 dizygotic twin pairs. Thirty-three cephalometric variables were measured using lateral cephalograms and were categorized as the anteroposterior, vertical, dental, mandible, and cranial base characteristics. The ACE model was used to calculate heritability (A > 0.7, high heritability). Thereafter, principal component analysis (PCA) was performed. Results Twin pairs in C-I group exhibited high heritability values in the facial anteroposterior characteristics, inclination of the maxillary and mandibular incisors, mandibular body length, and cranial base angles. Twin pairs in C-II group showed high heritability values in vertical facial height, ramus height, effective mandibular length, and cranial base length. PCA extracted eight components with 88.3% in the C-I group and seven components with 91.0% cumulative explanation in the C-II group. Conclusions Differences in the heritability of skeletodental characteristics between twin pairs with skeletal Class I and II malocclusions might provide valuable information for growth prediction and treatment planning.

In 3 to 10 % of cases, multiple sclerosis (MS) onset is before the age of 16, and in less than 1 % of patients — under the age of 10. In the modern domestic literature, there are no publications that would describe cases of MS in twins, but it is established that the concordance of monozygotic twins for MS is only 30 %. We observed and treated a dizygotic pair of twins with the onset of multiple sclerosis. It was found that a patient with more pronounced manifestations of sclerosis had a higher level of homocysteine compared to his twin brother, who had a few focal changes when using magnetic resonance imaging. In our opinion, it is advisable toexamine both children from a pair of twins for the diagnosis of multiple sclerosis, even when one of patients has symptoms and the other has no symptoms., У 3–10 % пациентов РС дебютирует именно в возрасте 16 лет и у менее 1 % пациентов — в возрасте до 10 лет. В современной отечественной литературе нет публикаций, которые бы описывали случаи РС у детей-близнецов, однако установлено, что конкордантность монозиготных близнецов по РС составляет всего лишь 30 %. Нами было проведено лечение и наблюдение за дизиготной парой близнецов с дебютом рассеянного склероза. Было установлено, что у пациента, который имел более яркие проявления рассеянного склероза, отмечен более высокий уровень гомоцистеина по сравнению с его братом-близнецом, у которого на МРТ немногочисленные очаговые изменения. По нашему мнению, целесообразно обследование обоих детей из пары близнецов в плане диагностики рассеянного склероза, даже когда один из пациентов имеет проявления заболевания, а у другого нет симптомов., У 3–10 % пацієнтів РС дебютує саме у віці 16 років та у менше ніж 1 % пацієнтів — у віці до 10 років. У сучасній вітчизняній літературі немає публікацій, що б описували випадки РС у дітей-близнюків, проте встановлено, що конкордантність монозиготних близнюків за РС становить усього лише 30 %. Нами було проведено лікування та спостереження за дизиготною парою близнюків, що мали дебют розсіяного склерозу. Було встановлено, що в пацієнта, який мав більш яскраві прояви розсіяного склерозу, відзначено більш високий рівень гомоцистеїну порівняно з його братом-близнюком, у якого на МРТ нечисленні вогнищеві зміни. На нашу думку, є доцільним обстеження обох дітей із пари близнюків щодо діагностики розсіяного склерозу, навіть коли один із пацієнтів має прояви захворювання, а в іншого немає симптомів.

Summary Background & aims The association between higher body mass index (BMI) and cardiometabolic diseases (CMDs, including type 2 diabetes and cardiovascular diseases) is not well understood. We aimed to examine the association of BMI and its long-term changes with cardiometabolic diseases (CMDs) and explore the role of familial background and healthy lifestyle in this association. Methods Within the Swedish Twin Registry, 36 622 CMD-free individuals aged ≥40 were followed for up to 16 years. BMI data was collected at baseline and 25–35 years prior to baseline. Healthy lifestyle (non-smoking, no/mild alcohol consumption, and regular physical activity) was assessed as unfavourable (none or only one of these factors) vs. favourable (two or three). Incident CMDs were identified by linkage with the Swedish National Patient Registry. Two strategies were followed: 1) Cox models in all twin individuals; 2) stratified Cox models in CMD-discordant twin pairs. Results At baseline, 16 195 (44.2%) study participants had overweight/obesity (BMI ≥ 25 kg/m2) and 11 202 (30.6%) developed CMDs over follow-up. Among all participants, the hazard ratio (HR) and 95% confidence interval (CI) of developing any CMD was 1.52 (1.45–1.58) for people with overweight/obesity compared to normal BMI (20–25 kg/m2). Compared to stable normal BMI, HRs (95% CIs) of CMDs were 1.28 (1.02–1.59) and 1.33 (1.24–1.43) for only earlier life or only later life overweight/obesity, respectively, and 1.69 (1.55–1.85) for overweight/obesity both in earlier and later life. In stratified Cox analyses conducted among all CMD-discordant twin pairs, overweight/obesity was associated with greater risk of CMDs (1.37, 95% CI 1.18–1.61). In joint effect analysis, the risk of CMDs related to overweight/obesity was diminished 32% among people with a favourable lifestyle (1.51, 95% CI 1.44–1.58) compared to those with overweight/obesity and an unfavourable lifestyle (2.20, 95% CI 2.03–2.38). Conclusions Overweight/obesity is associated with an increased risk of CMDs, and shared genetic and early-life environmental factors might not account for this association. However, a favourable lifestyle could attenuate the risk of high BMI-related CMDs.

Emerging evidence suggests socioeconomic disadvantage may increase risk for eating disorders (EDs). However, there are very few studies on the association between disadvantage and EDs, and all have focused on individual-level risk factors (e.g., family income). Neighborhood disadvantage (i.e., elevated poverty and reduced resources in one's neighborhood) is associated with increased risk for anxiety/depression and poor physical health. To date, no studies have examined phenotypic associations between neighborhood disadvantage and disordered eating, or how any form of disadvantage may interact with genetic individual differences in risk for EDs. We examined phenotypic and etiologic associations between neighborhood disadvantage and disordered eating in 2,922 girls ages 8-17 from same-sex twin pairs recruited through the Michigan State University Twin Registry. Parents rated the twins on nine items assessing core disordered eating symptoms (e.g., weight preoccupation, binge eating), and neighborhood disadvantage was calculated from 17 indicators of contextual disadvantage (e.g., median home value, neighborhood unemployment). Puberty was measured using the Pubertal Development Scale to examine whether associations were consistent across development. At a phenotypic level, greater neighborhood disadvantage was associated with significantly greater disordered eating symptoms in girls at all stages of puberty (β = .07). Moreover, Genotype × Environment models showed that girls living in more disadvantaged neighborhoods exhibited stronger and earlier (i.e., during pre/early puberty) activation of genetic influences on disordered eating. Results highlight the critical importance of considering contextual disadvantage in research on etiology and risk for disordered eating, and the need for increased screening and treatment for EDs in disadvantaged youth. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Objective To evaluate all individual cases of dual twin demise following laser surgery for twin-twin transfusion syndrome (TTTS). Method This is an analysis of all monochorionic diamniotic twin gestations with TTTS complicated by dual demise following laser surgery from 2006 to 2019. Cases were reviewed by (1) a fetal surgeon researcher and (2) a panel of independent experienced maternal-fetal medicine specialists to code an etiology of demise for the donor and recipient, and to assess for possible preventability. Results Of 753 twins that underwent laser surgery for TTTS, 52 (6.9%) had postoperative dual demise. In this subgroup, gestational age at surgery was 19.5 (16.1-24.9) weeks, and 36 (69.2%) patients were Quintero stage III and IV. The most common etiology was the spectrum of disorders leading to preterm delivery, which included cervical insufficiency, preterm premature rupture of membranes, and preterm labor (44.2% and 48.1%, donor and recipient, respectively). Some degree of preventability was estimated for 23.1% of dual demises. Conclusions The most common cause of dual demise post laser surgery for TTTS was preterm birth, reinforcing the need for studies regarding the etiology and prevention of post-fetoscopy prematurity. Nearly one-quarter of dual demise cases were deemed potentially preventable.

The effects of microstructure morphology on corresponding tensile mechanical properties of Ti–5Al–5Mo–5V–1Cr–1Fe alloy controlling by three different heat treatment conditions (solution, single-step and two-step aging) were investigated in the present paper. The results show that the solution temperature exhibited an important impact on the precipitation behavior of secondary-α phase (αs) during aging, in which the content of αs gradually increased with the increase of solution temperature. When the alloy was single-step aged at 500–600 ​°C, the needle-like αs precipitated from matrix, as well as the content of αs decreased and coarsened corresponding to the increase of aging temperature. Compared with single-step aging, the αs slightly increased when the alloy was subjected to two-step aging heat treatment. The tensile results show that the αs is the main strengthening phase in the alloy. Moreover, its content as well as the intensity of the precipitation mode directly affects the strength, whereas inevitably with an accompanying penalty on ductility. In general, the higher solution temperature and the lower first-step aging temperature result in a more intensive αs and then lead to the higher strength. Meanwhile, { 1 0 1 ¯ 2 } and { 1 0 1 ¯ 1 } twins were found in two-step aged tensile samples, which may impart twinning-induced plasticity (TWIP). Overall, this study demonstrates that the alloy can be heat treated to achieve an excellent match between strength and ductility and to provide sufficient stress and optional ductility (ultimate strength of 978–1439 ​MPa and elongation of 8.25–18.9%).

Observational studies have repeatedly linked cannabis use and increased risk of psychosis. We sought to clarify whether this association reflects a causal effect of cannabis exposure or residual confounding. We analyzed data from two cohorts of twins who completed repeated, prospective measures of cannabis use (N = 1544) and cannabis use disorder symptoms (N = 1458) in adolescence and a dimensional measure of psychosis-proneness (the Personality Inventory for DSM-5 Psychoticism scale) in adulthood. Twins also provided molecular genetic data, which were used to estimate polygenic risk of schizophrenia. Both cumulative adolescent cannabis use and use disorder were associated with higher Psychoticism scores in adulthood. However, we found no evidence of an effect of cannabis on Psychoticism or any of its facets in co-twin control models that compared the greater-cannabis-using twin to the lesser-using co-twin. We also observed no evidence of a differential effect of cannabis on Psychoticism by polygenic risk of schizophrenia. Although cannabis use and disorder are consistently associated with increased risk of psychosis, the present results suggest this association is likely attributable to familial confounds rather than a causal effect of cannabis exposure. Efforts to reduce the prevalence and burden of psychotic illnesses thus may benefit from greater focus on other therapeutic targets. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The field of human behavioral genetics has come full circle. It began by using twin/family studies to estimate the relative importance of genetic and environmental influences. As large-scale genotyping became cost-effective, genome-wide association studies (GWASs) yielded insights about the nature of genetic influences, and new methods that use GWAS data to estimate heritability and genetic correlations invigorated the field. Yet these newer GWAS methods have not replaced twin/family studies. In this review, we discuss the strengths and weaknesses of the two approaches with respect to characterizing genetic and environmental influences, measurement of behavioral phenotypes, and evaluation of causal models, with a particular focus on cognitive neuroscience. This discussion highlights how twin/family studies and GWAS complement and mutually reinforce one another.

Siblings of children with an intellectual disability (ID) have been studied for many years with respect to questions concerning the influence of their brother's or sister's ID on their wellbeing (Arnold and Heller, 2018; Marquis et al., 2019; Hayden et al., 2019). A number of related factors may partly explain the impact of having a brother or sister with ID on the wellbeing of siblings. First of all, behavioural problems of the child with ID were found to have a negative impact on the wellbeing of the sibling (Arnold and Heller, 2018). Factors that are known to contribute to the quality of life of these siblings are a closer relationship of the sibling with the brother or sister with a disability, a younger age than the child with ID, a primary caregiver's lower care burden, and female gender of siblings (Wakimizu et al. 2020). Also, the relationship between the parents may play a role, as this was shown to highly impact family functioning (Langley et al., 2021). Williams et al. (2022) found that maternal psychological distress was associated with more behaviour problems of the sibling and suggest their study is replicated with longitudinal data. In this project we propose a longitudinal study focusing on the wellbeing and behaviour of co-twins of a child with ID and its interaction with parent factors and externalizing behavioural of the child with ID. The concept of wellbeing can be described by several measures (Diener, 2009). In the dataset that we use from the Netherlands Twin Register (NTR), this concept was measured with the Self-Anchoring Ladder (single item; Cantril, 1965), which has a 2-year reliability (correlation) of 0.65 (Palmore & Kivett, 1977).

The ability to perceive approximate numerosity is present in many animal species, and emerges early in human infants. Later in life, it is moderately heritable and associated with mathematical abilities, but the etiology of the Approximate Number System (ANS) and its degree of independence from other cognitive abilities in infancy is unknown. Here, we assessed the phenotypic specificity as well as the influence of genetic and environmental factors on the ANS in a sample of 5-month-old twins (N = 514). We found a small-to-moderate but statistically significant effects of genetic factors on ANS acuity (heritability = 0.18, 95% CI: 0.02, 0.33), but only when differences in numerosity were relatively large (1:4 ratio). Non-verbal ability assessed with the Mullen Scales of Early Learning (MSEL) was found to be heritable (0.47; 95% CI: 0.34, 0.57) and the phenotypic association between ANS acuity and non-verbal ability performance was close to zero. Similarly, we found no association between ANS acuity and general attention during the task. An unexpected weak but statistically significant negative association between ANS auity and scores on the receptive language scale of the MSEL was found. These results suggest that early ANS function may be largely independent from other aspects of non-verbal development. Further, variability in ANS in infancy seems to, to some extent, reflect genotypic differences in the population. Assessing 514 infant twins with eye tracking, we found that infant’s sense of approximate numerosity is heritable and not positively associated with concurrent attentional, cognitive or motor abilities. These results have implications for our understanding of development of mathematical ability and the link between cognitive abilities early in postnatal life.

Background Emotion dysregulation (ED) is common in attention-deficit/hyperactivity disorder (ADHD) and often results in adverse outcomes. However, ED has been suggested as a transdiagnostic construct, why the specific association between ADHD and ED when adjusting for other mental health conditions needs further investigation. It is also important to determine the aetiological basis of the association between ADHD and ED to inform the theoretical conceptualization of ADHD. Method This study used a co-twin control design, including a sample of dizygotic (DZ) and monozygotic (MZ) twins (N = 389; 45.8% females, age = 8–31 years, MZ twin pairs 57.6%). ED was assessed using the dysregulation profile from the parent-rated Child Behaviour Checklist and its adult version. Regression analyses were used across individuals and within the pairs, while adjusting for diagnoses of autism, intellectual disability, other neurodevelopmental conditions and affective conditions. Results ADHD was significantly associated with ED, even when adjusting for age, sex, attention problems and other mental health conditions, and was the diagnosis most strongly associated with ED. Within-pair analyses revealed that twins with ADHD had higher levels of ED compared to their co-twin without ADHD. This association remained within DZ twins and was non-significant in the MZ subsample, with non-overlapping confidence intervals between the DZ and MZ estimates. Conclusion ADHD is strongly and in part independently linked to ED, stressing the importance of early detection and treatment of emotional difficulties within this group. The findings from the within-pair analyses indicate a genetic influence on the association between ADHD and ED.

The study of unstable plastic flow in porous steel 316L samples after compression deformation at room temperature with different strain rates was carried out. The samples were obtained from ASTM F3184 medical grade steel powder by digital metallurgy using a Renishaw AM 400 laser 3D printer. Serrations on the stress-strain curves and strain localization bends were found, which were associated with the Portevin-Le Chatelier effect and testified instability of the plastic flow of the material under the deformation process. Deformation twins were observed in the structure of deformed samples.

A Cu-1.79Ti-0.39Cr-0.1Mg (wt.%) alloy was prepared by a vacuum induction melting furnace in a high-purity argon atmosphere. The effects of room temperature rolling and cryogenic rolling on the microstructure, textures, and mechanical properties of the alloy were investigated by means of electron backscatter diffraction, transmission electron microscopy, and X-ray diffraction. The results show that the hardness of the cryogenically rolled alloy is 18–30 HV higher than that of the room temperature rolled alloy at any tested rolling reduction. The yield strength and tensile strength of the alloy cryogenically rolled by 90% reduction are 723 MPa and 796 MPa, respectively. With the increase of rolling reduction, the orientation density of the Cube texture decreases, while the Brass texture increases. The Brass texture is preferred especially during the cryogenic rolling, suggesting that the cross-slip is inhibited at the cryogenic temperature. The dislocation densities of Cu-Ti-Cr-Mg alloy increase significantly during the deformation, finally reaching 23.03 × 10−14 m−2 and 29.98 × 10−14 m−2 after a 90% reduction for the room temperature rolled and cryogenically rolled alloys, respectively. This difference could be attributed to the impediment effect of cryogenic temperature on dynamic recovery and dynamic recrystallization. The cryogenic temperature promotes the formation of the dislocation and the nano-twins, leading to the improvement of the mechanical properties of the alloy.

About 2 out of every 5 young children (below 5 years) have difficulty learning their native language (Roberts et al., 2019). For many late talkers, the delays in language resolve by age of 4 years (Bishop & Hayiou-Thomas, 2008; Norbury, 2015; Rescorla, 2011). However, some children continue to have persistent language problems and grow up to be adolescents with considerable language needs. In the UK, the prevalence of language disorder at age 5-6 years was estimated at 10%, with 7.6 % representing a language disorder with unknown origin (i.e., not related to intellectual disability or existing medical problems)(Norbury et al., 2016). Children with language difficulties are more likely to be the target of bullying and to experience emotional difficulties compared to their typically developing peers (Curtis et al., 2018; Lloyd-Esenkaya et al., 2020). While some studies show that the magnitude of these differences in socioemotional problems increases as children grow older (Curtis et al., 2018; Durkin & Conti-Ramsden, 2007), others find evidence that they reduce during adolescence (Forrest et al., 2020). Moreover, it has been suggested that children with language impairments experience more peer problems, arguably due to their difficulties in meeting the linguistic demands of a social exchange, poor conflict resolution and poor negotiation skills (Curtis et al., 2018; Forrest et al., 2018; Lindsay et al., 2008; van den Bedem Neeltje P. et al., 2018). The peer problems of children with language difficulties seem to be related to poor social use of language as well as structural language problems (Janik Blaskova & Gibson, 2021). Most studies looking at the association of developmental language problems with peer victimization are not genetically informative and do not account for genetic confounding. This is problematic given that strong evidence indicates that persistent DLD is heavily influenced by genetic factors (Bishop et al., 2003; Plomin et al., 2002) and emerging evidence suggests that the co-occurrence of language disorders and emotional problems is partially due to common genetic influences (Helland et al., 2020, Toseeb et al., 2020). Moreover, genetically informed studies have shown that genetic influences account for an important part of the variation in exposure to peer victimization (Ball et al., 2008; Bowes et al., 2013; Schoeler et al., 2019; St Pourcain et al., 2015). Finally, a recent study showed that a polygenic profile score for expressive language was associated with peer problems (Newbury et al., 2019). Here, we outline a study plan to investigate the contribution of language difficulties in childhood to the development of peer victimization across adolescence and young adulthood using a co-twin design to strengthen causal inference.