Twin Research And Human Genetics[JOURNAL]
Sun
200 papers
Trends in Birth Rates, Sex Ratio, and Infant Mortality Rates Among Singletons, Twins, and Higher Order Multiples in Brazil Between 2010 and 2023.
Lucci TK, Oliveira BS, Peixoto CM … +8 more , Rodrigues IR, Possani C, Prist R, Segal NL, Ponciano ELT, Saldiva SRDM, Carvalho MA, Otta E
Twin Res Hum Genet · 2026 Apr · PMID 41968853 · Publisher ↗
This study examines birth rates and infant mortality rates in Brazil among singletons, twins, and higher order multiples between 2010 and 2023. Data were obtained from the Brazilian Ministry of Health's Live Birth Inform...
This study examines birth rates and infant mortality rates in Brazil among singletons, twins, and higher order multiples between 2010 and 2023. Data were obtained from the Brazilian Ministry of Health's Live Birth Information System and Infant Mortality Information System. The dataset comprised 39,663,928 live births and 464,843 infant deaths occurring within the first year of life. Twin birth rates increased steadily over time, while singleton birth rates declined. The highest twin birth rates were observed in the Southeast (11.64‰) and South (11.47‰), whereas the lowest were observed in the North (7.81‰) and Northeast (9.23‰). Infant mortality among twins was approximately five times higher than among singleton, and higher order multiples faced an approximately threefold greater risk compared to singletons. Infant mortality rates were highest in the North and Northeast and lowest in the Southeast and South. Sex ratios varied by gestation type, with singletons showing the expected male bias and twins a slightly reduced male proportion, reflecting biological and regional influences on birth rates in Brazil. The data reveal a marked demographic shift between 2010 and 2023, with birth rates declining among women in their teens and 20s and increasing among those in their late 30s and 40s. Using Weinberg's differential method, we identified divergent trends in zygosity: dizygotic birth rates increased significantly over time, whereas monozygotic rates remained stable. This contrast underscores the environmentally responsive nature of dizygotic twinning, particularly its association with advancing maternal age and assisted reproductive technologies, compared to the relatively biologically stable pattern of monozygotic twinning.
umx version 4.5: Extending Twin and Path-Based SEM in R with CLPM, MR-DoC, Definition Variables, Ωnyx Integration, and Censored Distributions.
Castro-de-Araujo LFS, Gillespie NA, Neale MC … +1 more , Bates TC
Twin Res Hum Genet · 2026 Apr · PMID 41944398 · Publisher ↗
Structural equation modeling (SEM) is a flexible statistical technique with multiple applications, including behavioral genetics and social sciences. Building on the original design of the umx package, which improved acc...
Structural equation modeling (SEM) is a flexible statistical technique with multiple applications, including behavioral genetics and social sciences. Building on the original design of the umx package, which improved accessibility to OpenMx by specifying a concise syntax, umx v4.5 extends functionality for longitudinal and causal twin designs while improving interoperability with graphical modeling tools such as Onyx. New capabilities include: classic and modern cross-lagged panel models; Mendelian Randomization Direction-of-Causation (MR-DoC) twin models incorporating polygenic scores as instruments; support for definition variables directly in umxRAM(); a workflow for importing paths from Ωnyx; a dedicated function for incorporating censored variables' data into models, particularly valuable in biomarker research; improved covariate placeholder handling for definition variables; sex-limitation modeling across five twin groups, accommodating quantitative and qualitative sex differences; and covariate residualization in wide- or long-format data. These new functionalities accelerate reproducible, reliable, publication-ready twin and family modeling, and integrated journal-quality reporting, thereby lowering barriers to genetic epidemiological analyses.
The National Project on Achievement in Twins: Integrating Across Data Resources in the United States.
Hart SA, Hicks A, Poisall M … +6 more , Du H, Kennedy P, Gruen J, Taylor J, Ganley CM, Little CW
Twin Res Hum Genet · 2026 Mar · PMID 41913967 · Full text
The National Project on Achievement in Twins (NatPAT) is a twin project based in the United States (US) that began in 2017. Using a cohort sequential design, the overall goal of the initial project was to uncover salient...
The National Project on Achievement in Twins (NatPAT) is a twin project based in the United States (US) that began in 2017. Using a cohort sequential design, the overall goal of the initial project was to uncover salient factors, including genetic and environmental influences, which contribute to the co-development of reading and math performance during elementary school. In 2022, the focus of NatPAT pivoted towards a new focus on the COVID-19 pandemic's short- and long-term impacts on children's reading achievement. In addition, a genomics data collection began. New enrollment into the registry continues every year, but currently NatPAT follows 1997 twin pairs and their families as they progress through school. The project supports open science principles, with open materials and code, preregistration, and shared data. Here we present the goals of the project, summarize recent results, methods and materials, with a focus on the integration across many different data sources, and future directions of the project.
How Genomic and Structural Context Could Shape JAK-STAT Variant Pathogenicity.
Hoffmann M, Lee HK
Twin Res Hum Genet · 2026 Mar · PMID 41913962 · Full text
The Janus kinase (JAK)-Signal Transducer and Activator of Transcription (STAT) pathway is essential for cellular signal transduction, regulating immune responses, hematopoiesis, and cell proliferation. Dysregulation of J...
The Janus kinase (JAK)-Signal Transducer and Activator of Transcription (STAT) pathway is essential for cellular signal transduction, regulating immune responses, hematopoiesis, and cell proliferation. Dysregulation of JAK-STAT signaling due to genetic variations, particularly missense mutations, has been implicated in autoimmune disorders, cancers, and hematological malignancies. This study investigates missense mutations in JAK and STAT genes, focusing on disease-associated single nucleotide polymorphisms (SNPs) and ClinVar benign variants identified in the All of Us and COSMIC databases. We analyzed the distribution of these mutations across functional domains, their structural localization, and biochemical properties. We identified mutation hotspots within specific domains, highlighting their correlation with disease phenotypes. Structural mapping revealed that disease-associated SNPs predominantly localize in linker regions and at the boundaries of secondary structures, suggesting a significant impact on folding, stability, and function of JAK and STAT proteins. Additionally, we examined the genomic context of mutations and identified vulnerable sequences; for example, 'GATC'. Furthermore, our analysis found no predominant association between potential CRISPR-Cas9 target sites and ClinVar benign/disease-associated SNPs. The analysis of amino acid sequence patterns surrounding mutations uncovered an enrichment of hydrophobic residues leucine (Leu), isoleucine (Ile), methionine (Met), and phenylalanine (Phe) in close proximity to disease-associated mutations. Our findings emphasize the importance of structural and biochemical context in determining pathogenicity. In this study, we provide a bioinformatic strategy for refining variant classification and understanding the roles of JAK-STAT pathway mutations in disease.
The Murcia Twin Registry: 20 Years of Study and Progress in Health and Behavioral Traits in Spain.
Sánchez-Romera JF, Blanco-García FJ, Carrillo E … +7 more , Colodro-Conde L, González-Javier F, Madrid-Valero JJ, Martínez-Selva JM, Monteagudo O, Morosoli JJ, Ordoñana JR
Twin Res Hum Genet · 2026 Mar · PMID 41913940 · Publisher ↗
The Murcia Twin Registry (MTR) has steadily expanded over two decades and has become a key resource for twin research in the Mediterranean region. The registry currently includes data from 3971 individual twins born betw...
The Murcia Twin Registry (MTR) has steadily expanded over two decades and has become a key resource for twin research in the Mediterranean region. The registry currently includes data from 3971 individual twins born between 1940 and 1999, as well as an associated biobank containing samples from 1586 participants. Its primary research focus is on health and health-related behaviors within a public health framework, covering areas such as lifestyle, health promotion, quality of life, and environmental factors. Across multiple waves of data collection, the MTR has compiled extensive and wide-ranging phenotypic data. These data can be further expanded and have strong potential for record linkage with other health databases, particularly those of the regional public health care system, including both primary and inpatient care. Efforts are also underway to establish record linkage with additional sources of information, such as the educational system. In the near future, the registry aims to expand its biobank and continue the collection of longitudinal data, as well as increasing the ability to collect additional data that could enrich the information from participants in the register.
Are Spouses Similar in Divorce? Investigating Spousal Similarity in Couple-Shared Outcomes.
Sunde HF, Dierker P
Twin Res Hum Genet · 2026 Mar · PMID 41909959 · Publisher ↗
In behavioral genetics, divorce is typically analyzed as an individual-level outcome, even though marital dissolution can only be experienced by couples. In this article, we discuss how assortative mating complicates the...
In behavioral genetics, divorce is typically analyzed as an individual-level outcome, even though marital dissolution can only be experienced by couples. In this article, we discuss how assortative mating complicates the study of couple-shared outcomes because individual-level effects can be confounded by effects of the spouse. We then show how chain-linking affines (i.e., in-laws) provides sufficient information to estimate spousal similarity for couple-shared outcomes, which we incorporate into an extended twin model that we use to test for sex differences and assortative mating for individuals' liability to divorce. We linked the Norwegian twin register to the Norwegian population register and constructed 124,544 extended family units (1196 units with monozygotic twins) comprising 353,210 marriages entered between 1983 and 2008. We found that divorce was significantly correlated among affines, and that female relatives were more highly correlated than male relatives. The extended twin model estimated a strong correlation (r = .60, SE = .10) between female and male familial factors. Couples' liability to divorce was attributed to 18% (SE = 5%) female and 10% (SE = 3%) male familial factors, with an additional 16% (SE = 4%) accounted for by their correlation. Estimates from a classic twin model were considerably higher. These findings show that spousal similarity is an important source of variation in divorce liability and that failing to model it can inflate estimates of individual-level effects. Overall, the analytical framework offers a blueprint for dissecting any couple-shared outcome into sex-specific and assortative components.
Monozygotic Twins of Different Religions: Causes and Consequences/Twin Research Reviews: Language Development in Dizygotic Twins; MZ Twins with Hallermann-Streiff Syndrome; Digital Twins and Asthma Research; Zygosity Revealed/Human Interest: A Pen Turned Holocaust Children Into Twins; Identical Twin Winners; Twin Hostages Freed From Gaza; Loss of a Twin Son; Fraternal Twin Mountaineers; Twins in the Sydney to Hobart Yacht Race; Twin Patron Saints of Cobblers.
Segal N
Twin Res Hum Genet · 2026 Mar · PMID 41878832 · Publisher ↗
Monozyotic (MZ) twins reared together are typically raised in the same religion, as are all children in a family. However, a young pair of MZ male twins, raised together, but with different religions, was identified and...
Monozyotic (MZ) twins reared together are typically raised in the same religion, as are all children in a family. However, a young pair of MZ male twins, raised together, but with different religions, was identified and raises interesting issues that warrant consideration. This case, as well as those of reared-apart MZ twins who adopt different religions due to their family background or other circumstances, are summarized. A review of recent and current twin research follows. The studies included here concern language development in a pair of dizygotic (DZ) female twins, the second case of MZ twins with presumed Hallermann-Streiff syndrome, and the use of digital twins to advance asthma research. The final entry in the research section describes parents' responses to their twin children's misdiagnosed zygosity. Human interest stories involving twins - some entertaining, but all informative - include a pen that saved nontwin Holocaust children by assigning them as twins, identical twin winners, twin hostages freed from Gaza, loss of a twin son, fraternal twin mountaineers, twin sailors in the Sydney to Hobart Yacht Race, and the twin Patron Saints of Cobblers.
India's Twin Paradox: Abundant Resource, Absent Research.
Dhar R, Karmakar S
Twin Res Hum Genet · 2026 Mar · PMID 41869928 · Publisher ↗
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 systematical...
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.
Association Between Gestational Weight Gain And Spontaneous Preterm Birth In Chinese Women With Twin Pregnancies.
Wang L, Tang Y, Hu Y … +4 more , Muhuza Marie Parfaite U, Zhou M, Chen D, Liang Z
Twin Res Hum Genet · 2026 Feb · PMID 41716079 · Publisher ↗
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 pr...
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 []: 2.46, 95% CI [1.92, 3.15]), while women with excess GWG also had a significantly higher risk of SPTB (: 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.
International Normative Charts for Twin Weight, Length, and Head Circumference at Birth, By Gestational Age and Sex: The Twin Neonatal Cross-Sectional Study of the INTERGROWTH-21st Project.
Giuliani F, Deantoni S, Bertino E … +15 more , Jaffer YA, Purwar M, Barros FC, Cheikh Ismail L, Qingqing W, Stura I, Carvalho M, Gandino S, Winsey A, Gravett MG, Bhutta ZA, Papageorghiou AT, Migliaretti G, Kennedy SH, Villar J
Twin Res Hum Genet · 2026 Feb · PMID 41668416 · Publisher ↗
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 normati...
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): Integrating Behavioral Genetic, Molecular Genetic, and Epigenetic Research Across the Lifespan.
Smederevac S, Sadiković S, Dinić BM … +2 more , Milovanović I, Pajić D
Twin Res Hum Genet · 2026 Feb · PMID 41656925 · Publisher ↗
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 tha...
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 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.
Catch-Up Growth in Twins: The Influence of Chorionicity and Zygosity from Birth to School Age.
Correia L, Lucci TK, Moura L … +13 more , Peixoto CM, Brizot ML, de Carvalho MHB, Krebs V, Carvalho MA, Freitas JG, Albuquerque R, Lebaron-Khérif T, Ferreira IF, Arissi G, Luchesi LC, Pris R, Otta E
Twin Res Hum Genet · 2026 Feb · PMID 41645522 · Publisher ↗
This study evaluated the growth trajectories of twins from birth to school age, focusing on weight and height scores of children born in São Paulo. The longitudinal study comprised 188 healthy twins ( = 9.13 years; = 2...
This study evaluated the growth trajectories of twins from birth to school age, focusing on weight and height scores of children born in São Paulo. The longitudinal study comprised 188 healthy twins ( = 9.13 years; = 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 scores below the median decreased significantly, from 98.3% at birth to 31.4% at school age. At birth, the dispersion of -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 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.
Reared-Apart Twins From the Philippines: New Views of Lingering Questions/Twin Research Reviews: Twin Discordance for Multisystem Inflammatory Syndrome; IVF Twins and Hearing Impairment; Writing Styles of MZ Twins; Update on Twins with Feingold Syndrome/Human Interest: Conjoined Twin Girls Born in Sri Lanka, Conjoined Twin Boys Born in Papua, New Guinea, Update on Conjoined Twins Abby and Brittany Hensel, Twin Sentenced for Criminal Activities, and Correct Identification of an Identical Twin Culprit by DNA Sequencing.
Segal NL
Twin Res Hum Genet · 2026 Jan · PMID 41582784 · Publisher ↗
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 follow...
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.
Advancing Biobehavioral Research: An Overview and Update from the University of São Paulo Twin Panel.
Crosato EM, Brizot ML, Araujo JF … +29 more , Paula FV, Monticelli PF, Resende BD, Carvalho MHB, Carvalho MA, Fridman C, Mendes FM, Fraga MMB, Silva PHBD, Martinho HDS, Segal NL, Esseily R, Lucci TK, Prist R, Possani C, Peixoto CM, Tokumaru RS, Ferreira IF, Luchesi LC, Correia JL, Vieira EDAP, Lebaron-Khérif T, Freitas JG, Ueno ASO, Costa SMB, Machado TGO, Pontes LRA, Kupferman LI, Otta E
Twin Res Hum Genet · 2026 Jan · PMID 41574945 · Publisher ↗
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 pr...
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.
Urn Models have a Place in Genetics.
Stark A
Twin Res Hum Genet · 2026 Jan · PMID 41540846 · Publisher ↗
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...
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.
Heritability of Body Fat Percentage in Middle-aged and Older Qingdao Twins.
Cui F, Wang W, Tian X … +1 more , Zhang D
Twin Res Hum Genet · 2026 Jan · PMID 41536209 · Publisher ↗
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 traditi...
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.
Identification of Mediating Pathways Between Attention Deficit/Hyperactivity Disorder and Coronary Artery Disease and Heart Failure: A Two-Step Multivariable Mendelian Randomization Study.
Lin J, Zhou Y, Xie T … +7 more , Zhang J, Chen Z, Chang Z, Wang Y, Snieder H, Thio CHL, Hartman CA
Twin Res Hum Genet · 2026 Jan · PMID 41508840 · Publisher ↗
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...
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 ( 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 ( 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.
Human Genetics Society of Australasia Position Statement: Online or Direct-to-Consumer Genomics Testing.
Mansour J, McWhirter R, McLean A … +3 more , McIvor A, Heather N, Education, Ethics and Social Issues Committee of the Human Genetics Society of Australasia
Twin Res Hum Genet · 2025 Dec · PMID 41423726 · Publisher ↗
This position statement provides guidelines for health professionals who are considering online or direct-to-consumer genetic testing for their patients. It presents the major issues around online and direct-to-consumer...
This position statement provides guidelines for health professionals who are considering online or direct-to-consumer genetic testing for their patients. It presents the major issues around online and direct-to-consumer (DTC) testing including how it is accessed, motivations for accessing testing and how to return these results. Online or DTC recommendations include: (1) DTC testing should only be done by individuals/consumers who are well informed, aware of the risks, benefits and limitations of testing, and able to consent for their DNA to be collected, analyzed and potentially stored. Where possible, individuals/consumers should also be aware of the alternative option of undertaking testing through healthcare professionals in a clinical context, and the benefits of this. (2) Decisions about having a child tested should be based on peer-reviewed, published evidence. Genomics testing for children should be within a clinical context where parents are informed, have access to clinical support and professional genetic counseling about this decision, as well as support for the range of results received. (3) Parents considering direct-to-consumer testing on their newborn are counselled, or given information, to encourage them to have standard government funded newborn bloodspot screening testing on their newborn. (4) When choosing an online genomic test, preference should be given to tests undertaken in accredited laboratories offering tests accredited with the Therapeutic Goods Administration. (5) Results obtained through methods other than direct analysis from a laboratory accredited to perform genomic testing to inform human health and wellbeing should be interpreted with caution. The HGSA recommends that such results must be confirmed in an accredited diagnostic laboratory prior to relying on them to inform options for treatment, surveillance or risk reduction, or before undertaking cascade testing in family members. (6) When individuals are concerned about their health, they should consult an appropriate healthcare professional to decide whether an online genomic test is appropriate and discuss how useful test results could be to make health-related decisions.
The Interplay of Genes and Environment Across Multiple Studies (IGEMS) Consortium After Fifteen Years.
Finkel D, Finch BK, Gatz M … +21 more , Christensen K, Franz CE, Karlsson IK, Kremen WS, Krueger RF, Lupton M, Martin N, McGue M, Mosing MA, Neiderhiser J, Nygaard M, Prom-Worley E, Reynolds C, Sachdev P, Sillanpää E, Vuoksimaa E, Whitfield KE, Hayden O, Walters E, Pedersen NL, IGEMS consortium
Twin Res Hum Genet · 2025 Dec · PMID 41416461 · Full text
The Interplay of Genes and Environment across Multiple Studies (IGEMS) is a consortium of 21 twin studies from 5 countries (Australia, Denmark, Finland, Sweden, and United States) established to explore the nature of gen...
The Interplay of Genes and Environment across Multiple Studies (IGEMS) is a consortium of 21 twin studies from 5 countries (Australia, Denmark, Finland, Sweden, and United States) established to explore the nature of gene-environment interplay in cognitive, physical, and emotional health across the adult lifespan. The combined data from over 145,000 participants (aged 18 to 108 years at intake) has supported multiple research projects over the three phases of development since its inception in 2010. Phases 1 and 2 focused on launching and growing the consortium and supported important developments in data harmonization, analyses of data pooled across multiple studies, incorporation of linkages to national registries and conscription data, and integration of molecular genetic and classical twin designs. IGEMS Phase 3 focuses on developing appropriate infrastructure to maximize utilization of this large twin consortium for aging research.
Turner's Syndrome in Discordant Dizygotic Twins: Biological Origins and Twin Relations/Twin Research Reviews: Prevention of Premature Twin Birth; Twin Gestation with Hydatidiform Mole; Update on Feingold Syndrome Twins; Qualitative MZ Twin Difference Studies/Media: Identical Twins Turn 100 Years of Age; Twins in Famous Families; Celebration of Yorùbá Twins of Nigeria; Identical Artistic Partners; Rare Conjoined Twins Separated.
Segal NL
Twin Res Hum Genet · 2025 Dec · PMID 41340174 · Publisher ↗
A pair of dizygotic (DZ) twins discordant for Turner syndrome are discussed with reference to the biological origins of the condition and the effects of discordance on the twin relationship. There is little research on h...
A pair of dizygotic (DZ) twins discordant for Turner syndrome are discussed with reference to the biological origins of the condition and the effects of discordance on the twin relationship. There is little research on how having an atypical twin influences the life events and goals of the typical twin. Next, timely reviews of research on preventing premature twin birth, a twin gestation with hydatidiform mole, an update on Feingold syndrome twins discussed in a previous issue of this journal, and qualitative monozygotic twin difference studies are presented. The final portion of this article covers human interest stories of twins that are variously entertaining and enlightening. They include identical twins who celebrated their 100th birthday together, twins in famous families, celebration of the Yorùbá twins of Nigeria, identical artistic partners, and surgical separation of a rare, conjoined twin set.
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