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Journal of Obstetrics and Gynaecology... Jun 2023
Topics: Humans; Twins, Dizygotic; Gastroschisis; Twins, Monozygotic; Diseases in Twins
PubMed: 35589515
DOI: 10.1016/j.jogc.2021.02.121 -
Nature Human Behaviour Jun 2023In the classical twin design, researchers compare trait resemblance in cohorts of identical and non-identical twins to understand how genetic and environmental factors... (Review)
Review
In the classical twin design, researchers compare trait resemblance in cohorts of identical and non-identical twins to understand how genetic and environmental factors correlate with resemblance in behaviour and other phenotypes. The twin design is also a valuable tool for studying causality, intergenerational transmission, and gene-environment correlation and interaction. Here we review recent developments in twin studies, recent results from twin studies of new phenotypes and recent insights into twinning. We ask whether the results of existing twin studies are representative of the general population and of global diversity, and we conclude that stronger efforts to increase representativeness are needed. We provide an updated overview of twin concordance and discordance for major diseases and mental disorders, which conveys a crucial message: genetic influences are not as deterministic as many believe. This has important implications for public understanding of genetic risk prediction tools, as the accuracy of genetic predictions can never exceed identical twin concordance rates.
Topics: Humans; Twins, Dizygotic; Twins, Monozygotic; Mental Disorders; Risk Factors; Health Behavior
PubMed: 37188734
DOI: 10.1038/s41562-023-01609-6 -
American Journal of Ophthalmology Apr 2021To evaluate the degree of genetic influence on macular choroidal volume.
PURPOSE
To evaluate the degree of genetic influence on macular choroidal volume.
DESIGN
A cross-sectional twin and family study.
METHODS
In total, 353 Korean adults with healthy eyes from 78 households with 2 or more family members were included in the study. Macular choroidal volume was measured using spectral-domain optical coherence tomography with enhanced depth imaging at 9 macular subfields defined by the ETDRS. Demographics and clinical characteristics were investigated, including age, sex, axial length, hypertension, diabetes, drinking habits, and smoking status. The associations of these factors with macular choroidal volume were assessed using univariate and subsequent multivariate regression analyses while accounting for family structure. The heritability estimates of macular choroidal volume in total and at each of the 9 macular subfields were calculated after adjusting the covariates.
RESULTS
Patients who were younger, male, and had a shorter axial length showed associations with greater choroidal volume (P < .001 for all 3 independent variables). The covariates-adjusted heritability (±standard error) of the total macular choroidal volume was 0.76 ± 0.06, and the heritabilities of choroidal volume at each subfield ranged from 0.55 ± 0.09 (inner temporal subfield) to 0.77 ± 0.08 (inner superior subfield).
CONCLUSION
The macular choroidal volume is highly heritable.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Axial Length, Eye; Choroid; Cross-Sectional Studies; Female; Healthy Volunteers; Humans; Male; Middle Aged; Organ Size; Quantitative Trait, Heritable; Republic of Korea; Sibling Relations; Tomography, Optical Coherence; Twins, Dizygotic; Twins, Monozygotic; Young Adult
PubMed: 33340507
DOI: 10.1016/j.ajo.2020.12.008 -
Scientific Reports Jul 2022Individual differences in behaviour, traits and mental-health are partially heritable. Traditionally, studies have focused on quantifying the heritability of high-order...
Individual differences in behaviour, traits and mental-health are partially heritable. Traditionally, studies have focused on quantifying the heritability of high-order characteristics, such as happiness or education attainment. Here, we quantify the degree of heritability of lower-level mental processes that likely contribute to complex traits and behaviour. In particular, we quantify the degree of heritability of cognitive and affective factors that contribute to the generation of beliefs about risk, which drive behavior in domains ranging from finance to health. Monozygotic and dizygotic twin pairs completed a belief formation task. We first show that beliefs about risk are associated with vividness of imagination, affective evaluation and learning abilities. We then demonstrate that the genetic contribution to individual differences in these processes range between 13.5 and 39%, with affect evaluation showing a particular robust heritability component. These results provide clues to which mental factors may be driving the heritability component of beliefs formation, which in turn contribute to the heritability of complex traits.
Topics: Educational Status; Humans; Multifactorial Inheritance; Phenotype; Twins, Dizygotic
PubMed: 35821231
DOI: 10.1038/s41598-022-15492-0 -
American Journal of Obstetrics &... Mar 2022Twins represent 3.2% of all live births. However, they account for 20% of all preterm deliveries, with 60% delivered before 37 weeks and 10.7% before 32 weeks of... (Review)
Review
Twins represent 3.2% of all live births. However, they account for 20% of all preterm deliveries, with 60% delivered before 37 weeks and 10.7% before 32 weeks of gestation. Twin pregnancies have a 5 times higher risk of early neonatal and infant death related to prematurity. Monochorionic twins have a higher incidence of both indicated and spontaneous preterm delivery than dichorionic twins. Additional risk factors include a history of preterm delivery and cervical surgery. The transvaginal cervical length before 24 weeks is the best factor to predict preterm birth, independent of other risk factors.
Topics: Cervix Uteri; Female; Humans; Infant; Infant, Newborn; Pregnancy; Pregnancy, Twin; Premature Birth; Retrospective Studies; Twins, Dizygotic
PubMed: 34808401
DOI: 10.1016/j.ajogmf.2021.100531 -
Nature Mar 2022Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system underpinned by partially understood genetic risk factors and environmental...
Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system underpinned by partially understood genetic risk factors and environmental triggers and their undefined interactions. Here we investigated the peripheral immune signatures of 61 monozygotic twin pairs discordant for MS to dissect the influence of genetic predisposition and environmental factors. Using complementary multimodal high-throughput and high-dimensional single-cell technologies in conjunction with data-driven computational tools, we identified an inflammatory shift in a monocyte cluster of twins with MS, coupled with the emergence of a population of IL-2 hyper-responsive transitional naive helper T cells as MS-related immune alterations. By integrating data on the immune profiles of healthy monozygotic and dizygotic twin pairs, we estimated the variance in CD25 expression by helper T cells displaying a naive phenotype to be largely driven by genetic and shared early environmental influences. Nonetheless, the expanding helper T cells of twins with MS, which were also elevated in non-twin patients with MS, emerged independent of the individual genetic makeup. These cells expressed central nervous system-homing receptors, exhibited a dysregulated CD25-IL-2 axis, and their proliferative capacity positively correlated with MS severity. Together, our matched-pair analysis of the extended twin approach allowed us to discern genetically and environmentally determined features of an MS-associated immune signature.
Topics: Genetic Predisposition to Disease; Humans; Interleukin-2; Multiple Sclerosis; OX40 Ligand; Twins, Dizygotic; Twins, Monozygotic
PubMed: 35173329
DOI: 10.1038/s41586-022-04419-4 -
Human Reproduction (Oxford, England) Jan 2024Spontaneous dizygotic (DZ) twins, i.e. twins conceived without the use of ARTs, run in families and their prevalence varies widely around the globe. In contrast,... (Meta-Analysis)
Meta-Analysis
Spontaneous dizygotic (DZ) twins, i.e. twins conceived without the use of ARTs, run in families and their prevalence varies widely around the globe. In contrast, monozygotic (MZ) twins occur at a constant rate across time and geographical regions and, with some rare exceptions, do not cluster in families. The leading hypothesis for MZ twins, which arise when a zygote splits during preimplantation stages of development, is random occurrence. We have found the first series of genes underlying the liability of being the mother of DZ twins and have shown that being an MZ twin is strongly associated with a stable DNA methylation signature in child and adult somatic tissues. Because identical twins keep this molecular signature across the lifespan, this discovery opens up completely new possibilities for the retrospective diagnosis of whether a person is an MZ twin whose co-twin may have vanished in the early stages of pregnancy. Here, we summarize the gene finding results for mothers of DZ twins based on genetic association studies followed by meta-analysis, and further present the striking epigenetic results for MZ twins.
Topics: Female; Humans; Pregnancy; Fertilization; Genetic Association Studies; Retrospective Studies; Twins, Dizygotic; Twins, Monozygotic; Infant, Newborn
PubMed: 38052159
DOI: 10.1093/humrep/dead131 -
Journal of Attention Disorders Nov 2023We examined the characteristics and heritability of Autism Spectrum Disorder (ASD) and ADHD through a twin study.
OBJECTIVE
We examined the characteristics and heritability of Autism Spectrum Disorder (ASD) and ADHD through a twin study.
METHOD
Our sample included 44 twins, with at least one twin diagnosed with ASD. Among the participants, 30 had ASD, and 18 of them also had coexisting ADHD.
RESULTS
We observed higher concordance rates for ASD in monozygotic twins compared to dizygotic twins (67% vs. 25%), indicating a genetic influence on ASD. Inattentive symptoms of ADHD were more prevalent in monozygotic twins. The ASD + ADHD group exhibited significantly higher Social Responsiveness Scale scores, indicating greater social difficulties compared to the ASD and typical development groups. Twin analyses revealed that shared genetic factors accounted for 72.25% of the variance in both ASD and ADHD symptoms.
CONCLUSIONS
Our findings suggest that the comorbidity of ASD and ADHD may indicate increased severity and can be explained by shared genetic factors underlying both conditions.
Topics: Humans; Child; Autism Spectrum Disorder; Attention Deficit Disorder with Hyperactivity; Twins, Monozygotic; Twins, Dizygotic; Comorbidity
PubMed: 37480257
DOI: 10.1177/10870547231187166 -
Twin Research and Human Genetics : the... Dec 2019The Wisconsin Twin Project encompasses nearly 30 years of longitudinal research that spans infancy to early adulthood. The twin sample was recruited from statewide birth... (Review)
Review
The Wisconsin Twin Project encompasses nearly 30 years of longitudinal research that spans infancy to early adulthood. The twin sample was recruited from statewide birth records for birth cohorts 1989-2004. We summarize early recruitment, assessment, retention and recently completed twin neuroimaging studies. In addition to the focal twins, longitudinal data were also collected from two parents and nontwin siblings. Our adolescent and young adult neuroimaging sample (N = 600) completed several previous behavioral and environmental assessments, beginning shortly after birth. The extensive phenotyping is meant to support a range of empirical investigations with potentially differing theoretical perspectives.
Topics: Adolescent; Adult; Birth Certificates; Female; Humans; Longitudinal Studies; Male; Neuroimaging; Registries; Siblings; Temperament; Twin Studies as Topic; Twins, Dizygotic; Twins, Monozygotic; Wisconsin; Young Adult
PubMed: 31818344
DOI: 10.1017/thg.2019.108 -
JAMA Health Forum Jul 2021Wealthy adults tend to live longer than those with less wealth. However, a challenge in this area of research has been the reduction of potential confounding by factors...
IMPORTANCE
Wealthy adults tend to live longer than those with less wealth. However, a challenge in this area of research has been the reduction of potential confounding by factors associated with the early environment and heritable traits, which could simultaneously affect socioeconomic circumstances in adulthood and health across the life course.
OBJECTIVE
To identify the association between net worth at midlife and subsequent all-cause mortality in individuals as well as within siblings and twin pairs.
DESIGN SETTING AND PARTICIPANTS
This cohort study conducted a series of analyses using data from the Midlife in the United States (MIDUS) study, an ongoing national study of health and aging. The sample included adults (unrelated individuals, full siblings, and dizygotic and monozygotic twins) aged 20 to 75 years, who participated in wave 1 of the MIDUS study, which occurred from 1994 to 1996. The analyses were conducted between November 16, 2019, and May 18, 2021.
EXPOSURES
Self-reported net worth (total financial assets minus liabilities) at midlife (the middle years of life).
MAIN OUTCOMES AND MEASURES
All-cause mortality was tracked over nearly 24 years of follow-up, with a censor date of October 31, 2018. Survival models tested the association between net worth and all-cause mortality. Discordant sibling and twin analyses compared longevity within siblings and twin pairs who, given their shared early experiences and genetic backgrounds, were matched on these factors.
RESULTS
The full sample comprised 5414 participants, who had a mean (SD) age of 46.7 (12.7) years and included 2766 women (51.1%). Higher net worth was associated with lower mortality risk (hazard ratio [HR], 0.95; 95% CI, 0.94-0.97; < .001). Among siblings and twin pairs specifically (n = 2490), a similar within-family association was observed between higher net worth and lower mortality (HR, 0.94; 95% CI, 0.91-0.97; = .001), suggesting that the sibling or twin with more wealth tended to live longer than their co-sibling or co-twin with less wealth. When separate estimates were performed for the subsamples of siblings (HR, 0.94; 95% CI, 0.90-0.97; = .002), dizygotic twins (HR, 0.94; 95% CI, 0.86-1.02; = .19), and monozygotic twins (HR, 0.95; 95% CI, 0.87-1.04; = .34), the within-family estimates of the net worth-mortality association were similar, although the precision of estimates was reduced among twins.
CONCLUSIONS AND RELEVANCE
This cohort study found that wealth accumulation at midlife was associated with longevity in US adults. Discordant sibling analyses suggested that this association is unlikely to be simply an artifact of early experiences or heritable characteristics shared by families.
Topics: Adult; Aged; Cohort Studies; Female; Humans; Longevity; Longitudinal Studies; Male; Middle Aged; Social Class; Twins, Dizygotic; Twins, Monozygotic; United States; Young Adult
PubMed: 35977209
DOI: 10.1001/jamahealthforum.2021.1652