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ARYA Atherosclerosis Feb 2023The Isfahan Twin Cohort (ITC) aims to provide a comprehensive understanding of the interplay between genetics and environment in the development of Non-Communicable...
BACKGROUND
The Isfahan Twin Cohort (ITC) aims to provide a comprehensive understanding of the interplay between genetics and environment in the development of Non-Communicable Diseases (NCDs). As a type of specialized epidemiological investigation, twin studies are designed to quantify the contribution of genetics to a particular phenotype when confronted with environmental factors. In this context, the present study aims to present a detailed overview of the ITC methodology.
METHOD
The ITC is a prospective longitudinal study started in 2020. Data collection, including the demographics, socioeconomic status, health-related habits, medical history, and zygosity of the participants, was performed using validated questionnaires. Moreover, anthropometric measurements and blood pressure assessments were performed by a trained nurse. Also, fasting blood and morning urine samples were collected during a morning visit, and biochemical investigations were conducted at the central laboratory of the Isfahan Cardiovascular Research Institute. The participants underwent follow-up telephone interviews biannually, in which brief questionnaires were filled out on the changes in the lifestyle factors of the participants, such as diet, physical activity, psychological factors, and smoking habits. The second and final follow-up visit will include complete assessments, including blood and biological sample collections, similar to the baseline assessment.
RESULTS
The ITR has registered a total of 112 (n=224) monozygotic and 291 (n=582) dizygotic twin pairs during two years. The age range of the participants is 1 month to 56 years. Until November 2020 / 2021, the registered twins were categorized by age and included 48 pairs (n=96) in the infant group (monozygotic: 7 pairs, dizygotic: 41 pairs); 283 pairs (n=566) in the early childhood, late childhood, and adolescent groups (monozygotic: 74 pairs, dizygotic: 209 pairs); and 72 pairs (n=144) in the adult group (monozygotic: 31 pairs, dizygotic: 41 pairs).
CONCLUSIONS
The cohort is being prospectively followed with plans to investigate the clinical utility of the newly developed biomarkers and gene-environmental interactions in the future.
PubMed: 38883568
DOI: 10.48305/arya.2023.11881.2711 -
Genes, Brain, and Behavior Feb 2022Visual search guides goal-directed action in humans and many other species, and it has been studied extensively in the past. Yet, no study has investigated the relative...
Visual search guides goal-directed action in humans and many other species, and it has been studied extensively in the past. Yet, no study has investigated the relative contributions of genes and environments to individual differences in visual search performance, or to which extent etiologies are shared with broader cognitive phenotypes. To address this gap, we studied visual search and general intelligence in 156 monozygotic (MZ) and 158 same-sex dizygotic (DZ) twin pairs. We found that different indexes of visual search performance (response latency and visual search efficiency) were moderately heritable. Phenotypic correlations between visual search and intelligence were small-to-moderate, and only a small proportion of the genetic variance in visual search was shared with genetic variance in intelligence. We discuss these findings in the context of the "generalist genes hypothesis" stating that different cognitive functions have a common genetic basis.
Topics: Humans; Intelligence; Phenotype; Twins, Dizygotic; Twins, Monozygotic
PubMed: 35044053
DOI: 10.1111/gbb.12779 -
The Journal of Physiology Jun 2022We studied monozygotic (MZ) and dizygotic (DZ) twin pairs following resistance (RES) and endurance (END) training to assess genetic and environmental contributions to... (Randomized Controlled Trial)
Randomized Controlled Trial
We studied monozygotic (MZ) and dizygotic (DZ) twin pairs following resistance (RES) and endurance (END) training to assess genetic and environmental contributions to cerebrovascular function. Cerebrovascular function (rest, autoregulation, hypercapnia, exercise) was assessed in 86 healthy same-sex MZ (30 pairs) and DZ (13 pairs) twins, who underwent 3 months of END and RES. Carbon dioxide ( ), mean arterial pressure (MAP) and middle cerebral artery velocity (MCAv) were measured and MCAv resistance (MCA ) was calculated. Resting MCAv reduced by -2.8 cm/s following RES (P = 0.024), with no change following END (-0.3 cm/s, P = 0.758). Change in MCA following RES was +0.11 mmHg/cm/s (P < 0.001), which was significantly greater than END (+0.02 mmHg/cm/s, P = 0.030). MAP also increased following RES (+4 mmHg, P = 0.010), but not END (+1 mmHg, P = 0.518). No changes were apparent in . At rest, positive response rates following RES ranged from 27 to 71% and from 40 to 64% following END. Intraclass correlations between twins were moderate for most variables at baseline. In response to training, only MZ pairs were significantly correlated for a change in MCAv (P = 0.005) and low frequency phase (P = 0.047) following RES.This study is the first to compare cerebrovascular function following RES and END in MZ and DZ twins. Most individuals who did not respond to one modality were able to respond by switching modality, and baseline heritability estimates were higher than training response. Exercise professionals should therefore consider modality and environmental factors when optimising interventions. KEY POINTS: Characterising individual responses to resistance and endurance exercise training can inform optimal strategies for exercise prescription. This study utilised monozygotic and dizygotic twins in a randomised cross-over study to determine individual responsiveness to different modalities of exercise training. The influence of environment vs. genetics on cerebrovascular responses to training was determined. It is apparent that individuals respond differently to distinct exercise stimuli and that switching modality may be a beneficial way to obtain positive responses in cerebrovascular function. This study has implications for improving individualised exercise prescription to maintain or improve cerebrovascular structure and function.
Topics: Cerebrovascular Circulation; Cross-Over Studies; Endurance Training; Exercise; Humans; Middle Cerebral Artery; Twins, Dizygotic; Twins, Monozygotic
PubMed: 35474455
DOI: 10.1113/JP282998 -
Journal of Clinical Sleep Medicine :... May 2020Sleep quality and chronic neck pain (NP) are associated. However, the genetic influences on this association have not been explored. This study investigated the genetic...
STUDY OBJECTIVES
Sleep quality and chronic neck pain (NP) are associated. However, the genetic influences on this association have not been explored. This study investigated the genetic and environmental influences on the association between sleep quality and chronic NP.
METHODS
The sample comprised 2,328 individual twins from the Murcia Twin Registry (Spain). A bidirectional cotwin logistic regression analysis was performed (sleep quality assessed as the exposure and chronic NP as the outcome and vice versa). Analysis included 2 sequential stages: total sample analysis and within-pair twin case-control analysis.
RESULTS
Sleep quality was significantly associated with chronic NP in the total sample analysis (adjusted odds ratio [OR]: 1.09; 95% confidence interval [CI]: 1.06, 1.12; P < .001); in the cotwin case-control analysis, including both monozygotic and dizygotic twin pairs (adjusted OR: 1.10; 95% CI: 1.04, 1.17; P = .001); in dizygotic pairs (Adjusted OR: 1.11; 95% CI: 1.03, 1.19; P = .005); but not in monozygotic pairs (adjusted OR: 1.08; 95% CI: 0.98, 1.19; P = .118). Chronic NP was significantly associated with poor sleep quality in the total sample analysis (adjusted OR: 1.80; 95% CI: 1.43, 2.26; P < .001); in the cotwin case-control analysis, including both monozygotic and dizygotic twin pairs (Adjusted OR: 1.63; 95% CI: 1.07, 2.47; P = .023); in dizygotic pairs (Adjusted OR: 1.80; 95% CI: 1.05, 3.09; P = .031), but not in monozygotic pairs (adjusted OR: 1.67; 95% CI: 0.80, 3.48; P = .170).
CONCLUSIONS
The association between sleep quality and chronic NP is partially confounded by genetic factors.
Topics: Humans; Low Back Pain; Neck Pain; Sleep; Spain; Twins, Monozygotic
PubMed: 32026805
DOI: 10.5664/jcsm.8316 -
Genes Jan 2023to assess the influence of genetic and environmental factors using twin studies and evaluate the associations of SCARB1 gene variants (rs11057841) with AMD and MPOD.
THE AIM OF THE STUDY
to assess the influence of genetic and environmental factors using twin studies and evaluate the associations of SCARB1 gene variants (rs11057841) with AMD and MPOD.
MATERIAL AND METHODS
a total of 108 healthy twins (56 MZ and 52 DZ twins) were tested in this study. The MPOD was measured using the one-wavelength reflectometry method. Fundus reflectance (Visucam 500, reflectance of a single 460 nm wavelength) was used to measure the MPOD levels, MPOD parameters including max and mean optical density (OD), and area and volume. Real-time polymerase chain reaction was used to detect single nucleotide polymorphisms.
RESULTS
we detected a positive correlation of MPOD in the right and left eyes in MZ twin pairs (r = 0.830 and r = 0.860, respectively) ( < 0.0001) and a negative correlation of MPOD in the right and left eyes in DZ twin pairs (r = 0.314 and r = 0.408, respectively) ( < 0.05). The study was able to identify statistically significant differences in mean MPOD values in the right and left eyes between subjects with a wild-type CC genotype and a CT genotype with a risk allele. A decrease in the mean MPOD value was observed in group II with a CT genotype (0.110 d.u.) compared with the CC genotype (0.117 d.u.) in the right eye ( = 0.037) and in the left eye with a CT genotype (0.109 d.u.) compared with a CC genotype in the subjects (0.114 d.u.) ( = 0.038). In the right eye, in group II (0.101-0.128 d.u.), those with a CT genotype ( = 6) with one risk allele had a statistically significantly lower (0.110 d.u.) mean average MPOD value compared with those with a wild-type CC genotype ( = 25) (0.117 d.u.) ( = 0.037).
CONCLUSION
this twin study showed a strong heritability of the retina pigment, which was 86% prevalent in Lithuania. Individuals with a CT genotype of the SCARB1 rs11057841 with a risk allele had statistically significantly lower mean MPOD values in both eyes compared to subjects with a wild-type CC genotype.
Topics: Humans; Macular Pigment; Fundus Oculi; Twins; Genotype; Polymorphism, Single Nucleotide; Scavenger Receptors, Class B
PubMed: 36672866
DOI: 10.3390/genes14010125 -
Scientific Reports Feb 2021Infantile nystagmus (IN) may result from aetiologies including albinism and FRMD7 mutations. IN has low prevalence, and twins with IN are rare. Whilst discordant... (Observational Study)
Observational Study
Infantile nystagmus (IN) may result from aetiologies including albinism and FRMD7 mutations. IN has low prevalence, and twins with IN are rare. Whilst discordant presentation has been previously reported for IN, we present for the first time the comprehensive assessment of diagnostically discordant monozygotic twins. From a cohort of over 2000 patients, we identified twins and triplets discordant for nystagmus. Using next-generation sequencing, high-resolution infra-red pupil tracking and optical coherence tomography, we characterised differences in genotype and phenotype. Monozygotic twins (n = 1), dizygotic twins (n = 3) and triplets (n = 1) were included. The monozygotic twins had concordant TYR variants. No causative variants were identified in the triplets. Dizygotic twins had discordant variants in TYR, OCA2 and FRMD7. One unaffected co-twin demonstrated sub-clinical nystagmus. Foveal hypoplasia (FH) was noted in four of five probands. Both co-twins of the monozygotic pair and triplets displayed FH. In three families, at least one parent had FH without nystagmus. FH alone may be insufficient to develop nystagmus. Whilst arrested optokinetic reflex pathway development is implicated in IN, discordant twins raise questions regarding where differences in development have arisen. In unaffected monozygotes therefore, genetic variants may predispose to oculomotor instability, with variable expressivity possibly responsible for the discordance observed.
Topics: Child; Child, Preschool; Cohort Studies; Cytoskeletal Proteins; DNA Mutational Analysis; Diseases in Twins; Eye-Tracking Technology; Female; Genetic Variation; High-Throughput Nucleotide Sequencing; Humans; Male; Membrane Proteins; Membrane Transport Proteins; Monophenol Monooxygenase; Mutation; Nystagmus, Pathologic; Pedigree; Tomography, Optical Coherence; Twins, Dizygotic; Twins, Monozygotic
PubMed: 33531592
DOI: 10.1038/s41598-021-82368-0 -
Fertility and Sterility Sep 2020To investigate the relative contribution of genetic and environmental components to subfertility.
OBJECTIVE
To investigate the relative contribution of genetic and environmental components to subfertility.
DESIGN
Twin design using a quantitative genetic liability threshold model that splits the variation of subfertility into additive genetic effects, common environmental effects, and unique environmental effects.
SETTING
Not applicable.
PATIENTS
A total of 9053 Danish monozygotic and dizygotic same-sex twins aged 18+ years from nationwide twin surveys (twins born 1931-1976).
INTERVENTION
Not applicable.
MAIN OUTCOME MEASURES
Time to pregnancy (TTP) restricted to first pregnancy as a binary outcome, with a cut-off point of 10 months.
RESULTS
Based on the Akaike information criterion, a model including additive genetic and unique environmental factors resulted in the best model fit. For females, the relative contribution of additive genetic factors to TTP was 28% (95% confidence interval [CI] 15%, 41%), whereas unique environmental factors explained 72% (95% CI 59%, 85%). For males, additive genetic factors explained 4% (95% CI 0%, 22%) of the variation in TTP, while unique environmental factors accounted for 96% (95% CI 78%, 100%). Results were overall similar for the crude model and consistent across surveys.
CONCLUSION
Unique environmental factors explain most of the observed variation in subfertility, when measured as waiting time to pregnancy.
Topics: Aged; Cross-Sectional Studies; Denmark; Environment; Female; Fertility; Genetic Predisposition to Disease; Heredity; Humans; Infertility, Female; Infertility, Male; Male; Middle Aged; Phenotype; Risk Assessment; Risk Factors; Sex Factors; Time-to-Pregnancy; Twins, Dizygotic; Twins, Monozygotic
PubMed: 32624213
DOI: 10.1016/j.fertnstert.2020.03.014 -
Scientific Reports Aug 2022Both genetic and environmental influences have been proposed to contribute to the variance of gender identity and development of gender dysphoria (GD), but the magnitude...
Both genetic and environmental influences have been proposed to contribute to the variance of gender identity and development of gender dysphoria (GD), but the magnitude of the effect of each component remains unclear. We aimed to examine the prevalence of GD among twins and non-twin siblings of individuals with GD, using data derived from a large register-based population in Sweden over the period 2001-2016. Register data was collected from the Statistics Sweden and the National Board of Health and Welfare. The outcome of interest was defined as at least four diagnoses of GD or at least one diagnosis followed by gender-affirming treatment. A total of 2592 full siblings to GD cases were registered, of which 67 were twins; age at first GD diagnosis for the probands ranged from 11.2 to 64.2 years. No same-sex twins that both presented with GD were identified during the study period. The proportion of different-sex twins both presenting with GD (37%) was higher than that in same-sex twins (0%, Fisher's exact test p-value < 0.001) and in non-twin sibling pairs (0.16%). The present findings suggest that familial factors, mainly confined to shared environmental influences during the intrauterine period, seem to contribute to the development of GD.
Topics: Adolescent; Adult; Child; Diseases in Twins; Female; Gender Dysphoria; Gender Identity; Humans; Male; Middle Aged; Registries; Siblings; Twins; Twins, Dizygotic; Twins, Monozygotic; Young Adult
PubMed: 35927439
DOI: 10.1038/s41598-022-17749-0 -
Clinical Medicine & Research Aug 2020Cardiovascular anomalies are more common in monochorionic twins, especially with twin-twin transfusion, compared to other twin types and to singletons. Because previous...
BACKGROUND
Cardiovascular anomalies are more common in monochorionic twins, especially with twin-twin transfusion, compared to other twin types and to singletons. Because previous studies are based on fetal and neonatal echocardiography, more information is needed to study prevalence of cardiac anomalies in twin miscarriages, stillbirths, and children after the immediate neonatal period.
METHODS
With specific attention to cardiac anomalies, we reviewed the medical records of 335 selected liveborn twin pairs from the Marshfield Clinic Twin Cohort (enriched for twin-twin transfusion) and all twins (175 pairs) identified in the Wisconsin Stillbirth Service Program cohort of late miscarriages and stillbirths.
RESULTS
Structural cardiac defects occurred in 12% of liveborn monochorionic twin infants and 7.5% of stillborn infants with twin-twin transfusion compared to only 2% of liveborn dizygotic twins and no stillborn dizygotic infants. The most common cardiac lesion in liveborn twins was ventricular septal defect, which was usually isolated and discordant, preferentially affecting the smaller twin in monochorionic pairs. Among stillborn and miscarried monochorionic twins, the most common cardiac lesion was acardia.
CONCLUSIONS
Monochorionic twins, particularly those with TTT, are at increased risk for a spectrum of structural cardiac malformations which we suggest may be related to asymmetry of the inner cell mass resulting in a smaller poorly perfused twin. In severe cases, limited cardiac and circulatory development in the affected twin leads to acardia. In less severe cases, the smaller infant has deficient septal growth that sometimes results in ventricular septal defect.
Topics: Adolescent; Adult; Child; Child, Preschool; Female; Fetofetal Transfusion; Follow-Up Studies; Heart Defects, Congenital; Humans; Infant; Infant, Newborn; Live Birth; Male; Pregnancy; Risk Factors; Stillbirth; Twins, Monozygotic
PubMed: 31959670
DOI: 10.3121/cmr.2019.1478 -
Ultrasound in Obstetrics & Gynecology :... Jan 2023Previous small studies used individualized growth assessment (IGA) to characterize prenatal growth velocities of singletons and twins. We aimed to compare...
OBJECTIVE
Previous small studies used individualized growth assessment (IGA) to characterize prenatal growth velocities of singletons and twins. We aimed to compare second-trimester growth velocities of individual anatomical parameters between monochorionic diamniotic (MCDA) twins, dichorionic diamniotic (DCDA) twins and singleton fetuses in a larger study.
METHODS
This was a study of a novel cohort of 222 MCDA twins and previously published cohorts of 40 DCDA twins and 118 singletons with serial ultrasound data. Fetal biometric measurements of biparietal diameter, head circumference, abdominal circumference and femur diaphysis length from prenatal ultrasound examinations were used to calculate second-trimester growth velocities using direct calculation or linear regression analysis. Linear fit was assessed based on the coefficient of determination (R ). Mean growth velocities and variances were compared among the three groups.
RESULTS
The majority of cases underwent three second-trimester ultrasound examinations with fetal biometry available. All fetuses had linear growth, with R > 99% for all parameters. Only 1-2% of all MCDA and DCDA anatomical parameters had abnormal growth velocity scores outside the 95% reference range for singletons. There were no significant differences in mean growth velocity for any parameter between MCDA twins and singletons. Femur diaphysis length growth velocity was significantly lower in DCDA twins than in both MCDA twins and singletons. There were no other significant differences among the groups.
CONCLUSIONS
Expanding on prior work using IGA, we found that second-trimester growth velocity of the four major anatomical parameters overall was similar between twins and singletons and between MCDA and DCDA twins, supporting the use of singleton-derived growth standards for IGA in twins. Twin growth potential appears to be similar to that of singletons in the second trimester, suggesting that subsequent growth divergence may be due to third-trimester physiological or pathological changes in twin pregnancies. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.
Topics: Pregnancy; Female; Humans; Pregnancy Trimester, Second; Pregnancy, Twin; Twins, Dizygotic; Pregnancy Trimester, Third; Ultrasonography, Prenatal; Immunoglobulin A; Retrospective Studies; Twins, Monozygotic
PubMed: 36273412
DOI: 10.1002/uog.26102