Twin Research and Human Genetics最新文献

India's rising twin birth rate, driven by assisted reproductive technologies and delayed childbearing, generates approximately 30,000-40,000 twin pairs annually, yet this invaluable research resource remains systematically underutilized. While established twin registries in the United Kingdom, Australia, and Nordic countries have transformed understanding of disease heritability and gene-environment interactions, India, despite its 1.4 billion population and exceptional genetic diversity, lacks a coordinated infrastructure to capitalize on this scientific opportunity. Twin studies provide nature's ideal control experiment, enabling researchers to disentangle genetic predisposition from environmental influences through comparison of monozygotic and dizygotic pairs, with discordant twins offering particularly powerful insights into modifiable risk factors. India's extraordinary genetic heterogeneity, encompassing over 4600 distinct population groups, coupled with rapid environmental transitions including urbanization, dietary shifts, and pollution exposure, creates unparalleled natural experiments for investigating conditions demonstrating marked interpopulation variation such as type 2 diabetes, cardiovascular disease, and neuropsychiatric disorders. Establishing a National Twin Registry through a federated model linking existing birth registries with opt-in research participation, leveraging digital health infrastructure like Ayushman Bharat Digital Mission, would require modest investment while generating insights applicable across the disease spectrum. Initiating pilot registries in states with robust health systems such as Kerala, Tamil Nadu or Karnataka would enable iterative refinement before national expansion. International collaborations with established registries could accelerate development while preserving data sovereignty through robust governance frameworks. A National Twin Registry represents a strategic imperative for transitioning India from a research subject pool to a research leader in precision medicine, enabling Indian investigators to drive discovery addressing India-specific health priorities.

The studies on the association between maternal gestational weight gain (GWG) and spontaneous preterm birth (SPTB) in twin pregnancies are limited and inconsistent. There are no standardized guidelines for GWG in twin pregnancies in China. This retrospective cohort study included 1510 women who delivered living twins from January 1, 2015 to December 31, 2019. The basic demographics and outcomes of mothers and neonates were listed, and logistic regression was used to analyze the relationship between GWG and SPTB in the total population and different subgroups. In the overall population, 464 (30.7%) women had inadequate GWG, and 316 (20.9%) women had excess GWG. Compared to women with adequate GWG, women with inadequate GWG had a significantly higher risk of SPTB (adjusted odds ratio [aOR]: 2.46, 95% CI [1.92, 3.15]), while women with excess GWG also had a significantly higher risk of SPTB (aOR: 1.48, 95% CI [1.12, 1.95]). Both inadequate GWG and excess GWG had a significantly higher risk of SPTB in normal-weight women and women with dichorionic diamniotic twins. Only IGWG was significantly associated with SPTB in women with monochorionic diamniotic twins and underweight women. Our findings indicate that inadequate GWG and excess GWG were significantly associated with a higher risk of SPTB, providing an empirical basis for establishing weight gain guidelines for women with twin pregnancies in China.

Assessing the size of twins at birth using charts developed for singletons may over diagnose small for gestational age in this sub-population. The study aimed to produce international, twin-specific, newborn size normative charts by gestational age and sex. This longitudinal observational study in eight geographically diverse settings prospectively collected data between May 2009 and August 2013 from healthy pregnant women and their newborn twins. The participants were enrolled as part of the INTERGROWTH-21st study, and recruited based on World Health Organization recommendations for evaluation of anthropometric measures. All the women met, in addition to the underlying population characteristics of low perinatal risk, strict individual criteria for a population at low risk of impaired fetal growth. Newborn weight, length and head circumference measures were collected independently in duplicate by two trained anthropometrists within 12 hours of birth using identical equipment and protocols at all sites. From 1034 multiple pregnancies, after exclusions of condition such as smoking, high maternal BMI, and congenital malformations, the final sample was 864 twin newborns. Most of the twins were below the 50th centile of the INTERGROWTH-21st standards for singletons. We present international newborn size normative charts for twins using the same methodological approach adopted to construct the singleton standards.

The Serbian Twin Advanced Registry (STAR), established in 2014, is a multigenerational resource for studying genetic, environmental, and epigenetic influences on behavior and development. STAR currently includes more than 9000 participants, extending the classical twin design to parents and siblings and enabling fine-grained modeling of genetic inheritance, cultural transmission, and shared environments. Methodological innovations include experimental procedures, virtual reality paradigms, and longitudinal, multi-informant assessments from childhood to adulthood, combined with molecular data collection. Published findings highlight heritable structures in executive functions, personality, and psychopathology, alongside environmentally shaped differences in behaviors such as aggression. Epigenetic studies have demonstrated associations between COMT promoter methylation and impulsivity-related traits, while ongoing genomewide analyses aim to identify environmentally mediated methylation variability. By integrating advanced methodologies with open science practices, STAR provides a sustainable platform for behavioral genetics in Serbia and contributes to international research on adaptation and psychopathology across the lifespan.

This study evaluated the growth trajectories of twins from birth to school age, focusing on weight and height z scores of children born in São Paulo. The longitudinal study comprised 188 healthy twins (M = 9.13 years; SD = 2.16). Weight data were obtained from birth records and reassessed at school age, and height at school age. Singleton birth weights and standard growth curves were used as reference points. Overall, the proportion of children with z scores below the median decreased significantly, from 98.3% at birth to 31.4% at school age. At birth, the dispersion of z-scores below the median was significantly greater among monochorionic compared to dichorionic twins (2.051 vs. 1.701), but this difference was no longer observed at school age (1.861 vs. 0.976). In total, 68.8% of the twins showed improved weight development, with no cases of deterioration. While monozygotic (MZ) and dizygotic (DZ) twin pairs exhibited comparable intertwin birth-weight differences, by school age MZ pairs exhibited more similar weights, whereas DZ pairs showed significantly greater weight discrepancies. For height at school age, mean height z scores were within the expected range for singletons. No significant differences were observed between monochorionic and dichorionic twins, whereas MZ pairs showed smaller within-pair height differences than DZ pairs. These findings suggest that although chorionicity plays an important role during the perinatal period - particularly due to the lower birth weights observed among monochorionic twins - its influence diminishes over time. By school age, weight and height differences are primarily determined by zygosity.

This article presents an overview of the life histories of reared-apart twins from the Philippines. One twin always knew he was a twin, but for the other twin the discovery at age 15 came as a shock. This essay is followed by summaries of recent twin research of interest. Topics include twin discordance for multisystem inflammatory syndrome, in vitro fertilization (IVF) twins and possible associations with impaired hearing, the writings of monozygotic (MZ) twins, and an update on MZ twins with Feingold syndrome whom I have covered in a previous issue of this journal. This essay concludes with several twin-related human interest stories, namely conjoined twin girls from Sri Lanka, conjoined twin boys from Papua, New Guinea, recent information concerning conjoined twins Abby and Brittany Hensel, a twin sentenced for criminal activities, and accurate identification of an identical twin culprit by DNA sequencing.

The Painel USP de Gêmeos (University of São Paulo Twin Panel) is, based at the Instituto de Psicologia da Universidade de São Paulo. It was formally established in 2017 to advance research on fundamental psychological processes through twin study designs. Our relatively new registry comprises a volunteer sample of 8839 twin individuals, 70% of whom live in Brazil's Southeast, the region with the highest twinning birth rate (10.64‰) of the country, within a national population of 213 million. Our collaborative research group has expanded to include partners from psychology, dentistry, and medicine at USP, as well as other Brazilian institutions, such as the Universidade Federal do Rio Grande do Norte, Universidade Federal da Bahia, and Universidade Federal do Espírito Santo. We are advancing biobehavioral research in Brazil through innovative methodologies, interdisciplinary collaboration, and international partnerships. All twin participants contribute to multiple studies associated with four datasets employing the same hierarchical identification system for participants and families: the Biorepository, the Physiological and Physical Repository, the Behavioral Repository, and Fonoteca Cesar Ades (FOCA). Future directions include expanding our twin registry across the five regions of Brazil, our research partnerships, promoting genetic literacy, and fostering public engagement.

A simple application of urn models is useful in spelling out the way in which, in abstraction, if the parents are distributed in Hardy-Weinberg form, that form is reproduced in offspring with nonrandom mating. A measure of divergence from random mating is proposed and illustrated by numerical examples. The scope of urn models of stochastic processes in population genetics theory is set out.

Obesity represents a major global public health concern. Body fat percentage (BF%) is a key indicator for assessing adiposity and provides a more precise estimation of obesity-related health risks compared to the traditional body mass index (BMI). Accumulating evidence suggests that BF% is influenced by both genetic and environmental factors. However, most genetic studies on BF% have been conducted in European and American population, with limited data available from Chinese cohorts. To address this gap, a classical twin study was conducted using data from the Qingdao Twin Registry in China to estimate the heritability of BF% adjusted for age, sex, and BMI. This study included Han Chinese twins registered in the Qingdao Twin Registry. This study included 344 middle and old-aged Chinese twin pairs (217 monozygotic and 127 dizygotic). comprising 327 males and 361 females. The median age of participants was 50 (interquartile range [IQR]:12) years, with BF% of 27.6 (11.4) %. Model fitting indicated that the best-fitting model was AE model. The additive genetic effect (A) accounted for 54% (95% CI [44, 59) of the total variance, while unique environmental effect (E) contributed 46% (95% CI [37, 56]). In conclusion, this twin-based study provides robust evidence for a moderate genetic contribution (heritability = 54%) to BF% in a middle- and old-aged Qingdao population.

Attention deficit/hyperactivity disorder (ADHD) is associated with an increased risk of cardiovascular diseases (CVDs). However, whether this is a causal relation and how ADHD may predispose to a higher risk of CVD needs to be determined. We aimed to assess the causal association between ADHD and both coronary artery disease (CAD) and heart failure (HF), and to quantify the mediating effects of potential modifiable mediators. We conducted a two-step, two-sample Mendelian randomization (MR) study using SNPs as genetic instruments for exposure and potential mediators. Leveraging summary data on the latest genomewide association studies for ADHD, proposed mediators (i.e., metabolic factors, inflammatory factors, lifestyle behaviors, psychiatric disorders, and educational attainment), CAD and HF, we decomposed the total effect of ADHD on each outcome into direct and indirect effects through multiple mediators. Genetically predicted ADHD was associated with increased odds of CAD (OR 1.13; 95% CI [1.07, 1.19]), with educational attainment (EA) being the largest contributor (32.27% mediation, 95% CI [18.33%, 56.93%]). Body mass index (BMI), type 2 diabetes (T2D), EA, smoking initiation (SI), and depression jointly explained 83.59% (95% CI [63.95%, 101.49%]) of the association. Genetically predicted ADHD was associated with increased odds of HF (OR 1.11; 95% CI [1.05, 1.19]), with SI being the largest contributor (35.87% mediation, 95% CI [13.75%, 100.14%]). BMI, T2D, and SI jointly explained 82.39% (95% CI [45.90%, 131.60%]) of the association. The findings support a causal relationship between ADHD and both CAD and HF. Several modifiable risk factors substantially mediate these associations, suggesting potential targets for interventions aimed at reducing CVD risk in individuals with ADHD.