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Orthodontics & Craniofacial Research May 2020The aims of this longitudinal analysis of untreated monozygotic and dizygotic twins were to investigate vertical changes of the craniofacial structures during growth, to...
OBJECTIVE
The aims of this longitudinal analysis of untreated monozygotic and dizygotic twins were to investigate vertical changes of the craniofacial structures during growth, to determine the concordance between genetically twins and to assess the genetic component for the various aspects of vertical growth.
SETTINGS AND SAMPLE POPULATION
The sample consisted of 34 pairs of untreated monozygotic twins (23 male, 11 female) and 30 untreated dizygotic siblings of multiple birth (8 male, 8 female and 14 mixed) from the Forsyth Moorrees Twin Study (1959-1975); lateral cephalograms taken from 6 to 18 years of age were analysed at 3-year intervals.
MATERIALS AND METHODS
Cephalograms were traced, and longitudinal changes between twins in six angular and proportional vertical cephalometric variables (SN-NL, ML-NL, SN-ML, y-axis, PFH/AFH and LAFH/AFH) were analysed with intraclass correlation coefficients and linear regression modelling.
RESULTS
The concordance between monozygotic/dizygotic twins at 18 years of age was moderate to high with intraclass correlation coefficient values between 0.51 and 0.66. Additionally, sex differences in concordance at 18 years of age were found for three variables. High heritability (66%-79%) was observed for 5 of the 6 variables (LAFH/AFH, ML-NL, y-axis, SN-ML, PFH/AFH), while SN-NL showed limited heritability (34%).
CONCLUSIONS
Although monozygotic/dizygotic twins share at least part of their genetic material, differences in the vertical dimension were found. This supports the complex developmental mechanism of the human face and the varying influence of genetic and environmental factors.
Topics: Adolescent; Cephalometry; Child; Cohort Studies; Female; Humans; Longitudinal Studies; Male; Twins, Dizygotic; Twins, Monozygotic
PubMed: 31746097
DOI: 10.1111/ocr.12358 -
Nutrients Nov 2022This study investigated the contribution of genetic and environmental factors to cardiometabolic diseases (CMDs) by comparing disease concordance in monozygotic and...
Comparison of the Concordance of Cardiometabolic Diseases and Physical and Laboratory Examination Findings between Monozygotic and Dizygotic Korean Adult Twins: A Cross-Sectional Study Using KoGES HTS Data.
This study investigated the contribution of genetic and environmental factors to cardiometabolic diseases (CMDs) by comparing disease concordance in monozygotic and dizygotic twins. This cross-sectional study analyzed 1294 (1040 monozygotic and 254 dizygotic) twin pairs (>20 years) based on the Korean Genome and Epidemiology Study data (2005−2014). The odds ratios of disease concordance were calculated using binomial and multinomial logistic regression models. The occurrence of CMDs (hypertension, hyperlipidemia, type 2 diabetes, cerebral stroke, transient ischemic attack, and ischemic heart disease) and related physical and laboratory levels did not differ between the monozygotic and dizygotic twin groups. The odds for concordance of the presence/absence of CMDs and the likelihood of incident CMD within monozygotic twins were comparable to that of dizygotic twins. The absolute differences in hemoglobin A1c, insulin, low- and high-density lipoprotein cholesterol, total cholesterol, triglycerides, and systolic blood pressure were lower in monozygotic twins than in dizygotic twins. Absolute differences in fasting glucose and diastolic blood pressure did not differ between groups. Although baseline levels of several laboratory parameters related to CMD showed a strong likelihood of heritability in monozygotic twins, CMD phenotype appears to be largely affected by environmental factors.
Topics: Humans; Twins, Dizygotic; Cross-Sectional Studies; Diabetes Mellitus, Type 2; Ischemic Attack, Transient; Cholesterol, HDL; Republic of Korea
PubMed: 36432523
DOI: 10.3390/nu14224834 -
International Dental Journal Feb 2024The aim of this research was to collate and analyse the data on the oral health knowledge and the related habits of a Hungarian cohort of monozygotic (MZ) and dizygotic...
OBJECTIVE
The aim of this research was to collate and analyse the data on the oral health knowledge and the related habits of a Hungarian cohort of monozygotic (MZ) and dizygotic (DZ) twins using the newly developed World Health Organisation Oral Health Questionnaire for Adults (Annex 7).
METHOD
A total of 15 sets of MZ twins and 14 sets of DZ twins (58 individuals) aged between 18 and 71 years were enrolled in the study. Each participant had to fill out a web-based questionnaire which comprised 23 questions (Google Forms). The data were collated and the oral health/hygiene habits of MZ and DZ twins were compared.
RESULTS
No significant differences were detected between MZ and DZ twins with regards to their daily tooth-cleaning habits or the tooth-cleaning products used by the 2 groups. For instance, when asked how often they clean their teeth, 80% of MZ twins and 71% of DZ twins responded similarly. Further, both groups provided similar responses when questioned about the use of fluoride toothpaste, frequency of dental visits, and dental counselling received as well as a number of other parameters such as snacking of sweets and fear of visiting dentists.
CONCLUSIONS
Our pilot analysis of the questionnaire responses from MZ and DZ twins in Hungary did not indicate any significant differences in their oral care habits in general. Further studies with a large cohort are required to confirm or refute our findings.
Topics: Adult; Humans; Adolescent; Young Adult; Middle Aged; Aged; Twins, Dizygotic; Pilot Projects; Hungary; Oral Health; Habits
PubMed: 37482503
DOI: 10.1016/j.identj.2023.06.012 -
Nutrients Sep 2022We explored the genetic and environmental inter-relationships among osteoporosis, fracture, arthritis, and bone mineral density concordance in monozygotic twins compared...
Comparison of the Coincidence of Osteoporosis, Fracture, Arthritis Histories, and DEXA T-Score between Monozygotic and Dizygotic Twins: A Cross-Sectional Study Using KoGES HTS Data.
We explored the genetic and environmental inter-relationships among osteoporosis, fracture, arthritis, and bone mineral density concordance in monozygotic twins compared to those in dizygotic twins. This cross-sectional research assessed data of 1032 monozygotic and 242 dizygotic twin pairs aged >20 years included in the Healthy Twin Study data of the Korean Genome and Epidemiology Study between 2005 and 2014. Outcomes of interest included illness concordance and absolute differences in dual-energy X-ray absorptiometry (DEXA) T-scores. We found comparable concordances of osteoporosis, fractures, osteoarthritis, and rheumatoid arthritis between monozygotic and dizygotic twins. Medical histories of osteoporosis, fractures caused by accident or falling, osteoarthritis, and rheumatoid arthritis were not distinct between monozygotic and dizygotic twins. Accidental fracture occurrence in both monozygotic twins showed significantly lower odds than that in dizygotic twins. Genetic influence on liability to fracture risk might thus be maintained. DEXA T-scores for bone mineral density indicated more comparable tendencies within monozygotic twin pairs than within dizygotic ones, suggesting the relative importance of genetic contribution to bone mineral density. The relative importance of genetic factors in bone mineral density is sustained between monozygotic twins; overt disease expression of osteoporosis, fractures, or arthritis may be affected by environmental factors.
Topics: Arthritis, Rheumatoid; Cross-Sectional Studies; Diseases in Twins; Fractures, Bone; Humans; Osteoarthritis; Osteoporosis; Twins, Dizygotic
PubMed: 36145209
DOI: 10.3390/nu14183836 -
Behavior Genetics May 2018Social relationships play a critical role in health and well-being throughout life. We analyzed the genetic and environmental variance co-variance structure for social...
Social relationships play a critical role in health and well-being throughout life. We analyzed the genetic and environmental variance co-variance structure for social support and strain across four sets of relationships including with one's co-twin, spouse/partner, family and friends. The sample included 5288 Norwegian twins aged 40-80. Older people reported less support from their co-twin and friends and less strain from their family and friends. Genetic influences contribute importantly to variation across all the measures, with estimates ranging from 0 to 58%; variance due to shared environmental influences was most important for the twin-relationship, ranging from 0.11 to 0.42%. Social support was negatively correlated with social strain across all sets of relationships. With the exception of the co-twin relationship, these associations were primarily mediated by genetic and non-shared environmental effects.
Topics: Adult; Aged; Aged, 80 and over; Confidence Intervals; Family Relations; Female; Humans; Male; Middle Aged; Models, Biological; Social Support; Twins; Twins, Dizygotic; Twins, Monozygotic
PubMed: 29651684
DOI: 10.1007/s10519-018-9899-x -
PloS One 2016The similar genetic background of a pair of twins, and the similar environmental impacts to which they are exposed allow an exact and objective investigation of various...
BACKGROUND
The similar genetic background of a pair of twins, and the similar environmental impacts to which they are exposed allow an exact and objective investigation of various constitutional and environmental factors in naevus development. As far as we are aware, this is the first published survey that simultaneously examines cutaneous and ocular pigmented lesions in an appreciable sample of identical and non-identical twins.
METHODS
172 pairs of twins of Caucasian origin were included in this study. A whole-body skin examination and a detailed ophthalmological examination were performed to determine the density of melanocytic lesions. A standardized questionnaire was used to assess the data relating to constitutional, sun exposure and other variables.
RESULTS
A notably high proportion of the subjects (36.78%) manifested one or more clinically atypical melanocytic naevi (CAMNs), and approximately one-third (31.4%) of them at least one benign uveal pigmented lesion (BUPL). The incidence of iris freckles (IFs), iris naevi (INs) and choroidal naevi (CHNs) proved to be 25.35%, 5.98% and 3.52%, respectively. The interclass correlation coefficients for common melanocytic naevi (CMNs), CAMNs, and INs were 0.77, 0.76 and 0.86 in monozygotic twins, as compared with 0.5, 0.27 and 0.25 in dizygotic twin pairs, respectively. A statistically significant correlation was found between the prevalence of CAMNs and that of INs.
CONCLUSIONS
This significant correlation suggests the existence of a subgroup of Caucasian people with an increased susceptibility to both cutaneous and ocular naevus formation. There is accumulating evidence that, besides the presence of cutaneous atypical naevi, INs can serve as a marker of a predisposed phenotype at risk of uveal melanoma. The correlation between cutaneous and ocular pigmented lesions underlines the need for the adequate ophthalmological screening of subjects with CAMNs and INs.
Topics: Adolescent; Adult; Child; Child, Preschool; Dysplastic Nevus Syndrome; Female; Humans; Infant; Male; Melanoma; Nevus, Pigmented; Risk Factors; Skin Neoplasms; Twins, Dizygotic; Twins, Monozygotic; Uveal Neoplasms; Young Adult
PubMed: 27486750
DOI: 10.1371/journal.pone.0160146 -
Orthodontics & Craniofacial Research Nov 2022The purpose of this investigation of untreated monozygotic and dizygotic twins was to identify the genetic and environmental components to the facial soft tissue growth.
OBJECTIVE
The purpose of this investigation of untreated monozygotic and dizygotic twins was to identify the genetic and environmental components to the facial soft tissue growth.
SETTINGS AND SAMPLE POPULATION
The sample consisted of 52 untreated monozygotic twins (36 male and 16 female) and 46 untreated dizygotic twins (23 male and 23 female) from the Forsyth Moorrees Twin Study (1959-1975).
MATERIALS AND METHODS
Lateral cephalograms were taken at 12 and 17 years of age and traced to analyse facial convexity, nasolabial angle, upper and lower lip thickness, upper and lower lip profile and nose prominence. The genetic and environmental components of variance were analysed with structural equation modelling for multilevel mixed-effects model.
RESULTS
At 12 years of age, strong additive genetic influence was seen for facial convexity (70%), upper lip profile (66%) and nose prominence (65%), whereas strong dominant genetic components were found for upper lip thickness (56%). Nevertheless, under unique environment influence were nasolabial angle (58%), lower lip profile (51%) and lower lip thickness (64%). At 17 years of age, only upper lip thickness (55%) and nose prominence (84%) were under strong additive genetic control, while the rest of the variables were under strong dominant genetic control. The only exception was lower lip thickness (61%), which is still influenced by the unique environment.
CONCLUSION
Although monozygotic/dizygotic twins share at least part of their genome, at both times either additive, dominant or environmental components were found. Nevertheless, at 17 years of age most of the variables are either under additive or dominant genetic influence.
Topics: Cephalometry; Face; Female; Humans; Male; Retrospective Studies; Twins, Dizygotic; Twins, Monozygotic
PubMed: 35014186
DOI: 10.1111/ocr.12565 -
JAMA Psychiatry Jul 2023General and specific factors of psychopathology are associated with future adverse outcomes, indicating that they might be useful for identifying individuals at greatest...
IMPORTANCE
General and specific factors of psychopathology are associated with future adverse outcomes, indicating that they might be useful for identifying individuals at greatest risk. However, it remains unknown if these associations are attributable to confounders that may influence both the psychopathology factors and later outcomes.
OBJECTIVE
To analyze associations between psychopathology factors and clinically relevant outcomes within family pairs, adjusting for unmeasured confounds by applying co-twin control and sibling comparison designs.
DESIGN, SETTING, AND PARTICIPANTS
This longitudinal cohort study with a follow-up range of 9 to 13 years included all Swedish twins born from 1959 to 1985 who participated in the Study of Twin Adults: Genes and Environment (60% response rate) and the oldest pair of all Swedish siblings born from 1959 to 1985 per the Multi-Generation Register. Twins were evaluated based on responses to a hierarchical factor model derived using multivariate statistics. Sibling pairs were evaluated based on psychiatric diagnoses per the Swedish National Patient Register. Information on outcome events and prescriptions were derived from the National Patient Register, Prescribed Drug Register, and Crime Register. Baseline assessment was in August 2005, and data were analyzed from January 2022 to February 2023.
EXPOSURES
Hierarchical factor model consisting of 1 general and 4 specific factors fit to 48 psychiatric symptoms on which twin participants self-reported in 2005 and 1 general and 3 specific factors fit to 9 register-based psychiatric diagnoses assigned to sibling participants prior to 2005.
MAIN OUTCOMES AND MEASURES
Outcomes consisted of 7 register-based events occurring after 2005, including suicidal behavior, substance overdoses, and criminal suspicion or convictions (data available until the end of 2013), and prescription of antidepressants, antialcohol or antiopioid medication, antipsychotics, and stimulants (data available until the end of 2017).
RESULTS
The study included 32 328 twins (mean [SD] age, 34 [8] years; 16 076 [49.73%] male) and 1 942 106 siblings (mean [SD] age, 34 [7] years; 991 500 [51.05%] male). General psychopathology was significantly associated with all 7 outcomes within sibling pairs (mean within-pair odds ratio [OR], 2.28; 95% CI, 2.19-2.37) and dizygotic twin pairs (within-pairs OR, 1.65; 95% CI, 1.38-1.98) and with 3 outcomes within monozygotic twin pairs (mean within-pairs OR, 1.77; 95% CI, 1.35-2.36). Within sibling pairs, the specific internalizing factor was associated with antidepressant prescriptions (within-pairs OR, 1.65; 95% CI, 1.59-1.71), the specific substance misuse factor was associated prescription of antialcohol and antiopioid medication (within-pairs OR, 2.36; 95% CI, 2.20-2.54), and the specific psychotic factor was associated with antipsychotic medications (within-pairs OR, 1.61; 95% CI, 1.51-1.72). Similar results emerged within twin pairs.
CONCLUSION AND RELEVANCE
In this cohort study, general psychopathology was significantly associated with all 7 outcomes within sibling and dizygotic twin pairs and 3 outcomes within monozygotic twin pairs at 10 years. Within twin and sibling pairs, the specific factors were primarily associated with related outcomes. Several of the associations in this cohort study could not be attributed to unmeasured confounds shared by family members, suggesting that interventions toward broad psychopathology dimensions might help reduce the risk of future clinically relevant events.
Topics: Humans; Adult; Male; Female; Siblings; Longitudinal Studies; Sweden; Twins, Monozygotic; Mental Disorders; Twins, Dizygotic; Registries
PubMed: 37163290
DOI: 10.1001/jamapsychiatry.2023.1162 -
ELife Jul 2020Losing a co-twin by death is a severely stressful event yet with unknown impact on the surviving twin's risk of psychiatric disorders. We identified all Swedish-born...
Losing a co-twin by death is a severely stressful event yet with unknown impact on the surviving twin's risk of psychiatric disorders. We identified all Swedish-born twins who lost a co-twin by death between 1973 and 2013 (n = 4,528), their 4939 non-twin full siblings, together with 22,640 age- and sex-matched non-bereaved twins. Compared to the non-bereaved twins, exposed twins were at increased risk of receiving a first diagnosis of psychiatric disorders (hazard ratio = 1.65, 95% confidence interval1.48-1.83), particularly during the first month after loss. Similarly, compared to non-twin full siblings, the relative risks were significantly increased after loss of monozygotic co-twin (2.45-fold), and loss of a dizygotic co-twin (1.29-fold), with higher HR observed with greater age gaps between twins and non-twin siblings. As dizygotic twins share equal genetic relatedness to the deceased twin as their full siblings, this pattern suggests that beyond the contribution of genetic factors, shared early life experiences and attachment contribute to the risk of psychiatric disorders among surviving twins after co-twin loss.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Child; Cohort Studies; Female; Humans; Incidence; Male; Mental Disorders; Middle Aged; Risk Factors; Sweden; Twins, Dizygotic; Twins, Monozygotic; Young Adult
PubMed: 32660693
DOI: 10.7554/eLife.56860 -
Psychological Medicine Feb 2023Anxiety disorders are highly prevalent with an early age of onset. Understanding the aetiology of disorder emergence and recovery is important for establishing...
BACKGROUND
Anxiety disorders are highly prevalent with an early age of onset. Understanding the aetiology of disorder emergence and recovery is important for establishing preventative measures and optimising treatment. Experimental approaches can serve as a useful model for disorder and recovery relevant processes. One such model is fear conditioning. We conducted a remote fear conditioning paradigm in monozygotic and dizygotic twins to determine the degree and extent of overlap between genetic and environmental influences on fear acquisition and extinction.
METHODS
In total, 1937 twins aged 22-25 years, including 538 complete pairs from the Twins Early Development Study took part in a fear conditioning experiment delivered remotely via the Fear Learning and Anxiety Response (FLARe) smartphone app. In the fear acquisition phase, participants were exposed to two neutral shape stimuli, one of which was repeatedly paired with a loud aversive noise, while the other was never paired with anything aversive. In the extinction phase, the shapes were repeatedly presented again, this time without the aversive noise. Outcomes were participant ratings of how much they expected the aversive noise to occur when they saw either shape, throughout each phase.
RESULTS
Twin analyses indicated a significant contribution of genetic effects to the initial acquisition and consolidation of fear, and the extinction of fear (15, 30 and 15%, respectively) with the remainder of variance due to the non-shared environment. Multivariate analyses revealed that the development of fear and fear extinction show moderate genetic overlap (genetic correlations 0.4-0.5).
CONCLUSIONS
Fear acquisition and extinction are heritable, and share some, but not all of the same genetic influences.
Topics: Humans; Fear; Extinction, Psychological; Conditioning, Classical; Anxiety; Twins, Dizygotic
PubMed: 34474701
DOI: 10.1017/S0033291721002580