Journal articles on the topic 'Australian twins'
To see the other types of publications on this topic, follow the link: Australian twins.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Australian twins.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Sadrzadeh, Sheda, Susan A. Treloar, G. Caroline M. van Baal, and Cornelis B. Lambalk. "Potential Bias Regarding Birth Weight in Historical and Contemporary Twin Data Bases." Twin Research 4, no. 5 (October 1, 2001): 332–36. http://dx.doi.org/10.1375/twin.4.5.332.
Full textAbstract:
AbstractIn this study we examine the hypothesis that monozygotic (MZ) twins in historical databases are less discordant for birth weight due to negative selection of severely discordant MZ twins. Furthermore, we test the hypothesis that MZ twins are less discordant for birth weight when comparing a volunteer based twin registry with a population based twin registry, due to selective registration. Data were available on 3927 twin pairs from the volunteer Australian Twin Registry born before 1964, 3059 volunteer twin pairs from the Netherlands Twin Register born 1987–1989 and 454 Belgian twin pairs from The East Flanders Prospective Twin Survey born 1987–1989. Intrapair relative birth weight differences (RBWD) were computed for MZ and dizygotic (DZ) twins from each twin registry. Comparing birth weight differences between MZ and DZ twins provides support for the hypothesis that MZ twins are subject to a negative selection in historical databases. Furthermore, Australian MZ twins have a lower RBWD compared to Dutch MZ twins when corrected for the RBWD of Australian and Dutch DZ twins, indicating circumstances which only affect MZ twins. Our hypothesis that MZ twins are less discordant for birth weight in a volunteer based twin registry compared to a population based twin registry had to be rejected. We suggest that investigators using historical databases to test the fetal origins hypothesis should be aware of this increased likelihood of selective exclusion of individuals with extreme morphometric parameters at time of birth.
2
Hopper, John L., Debra L. Foley, Paul A. White, and Vincent Pollaers. "Australian Twin Registry: 30 Years of Progress." Twin Research and Human Genetics 16, no. 1 (December 3, 2012): 34–42. http://dx.doi.org/10.1017/thg.2012.121.
Full textAbstract:
The Australian Twin Registry (ATR) is a national volunteer resource of twin pairs and higher-order multiples willing to consider participating in health, medical, and scientific research. The vision of the ATR is ‘to realize the full potential of research involving twins to improve the health and well-being of all Australians’. The ATR has been funded continuously by the National Health and Medical Council for more than 30 years. Its core functions entail the recruitment and retention of twin members, the maintenance of an up-to-date database containing members’ contact details and baseline information, and the promotion and provision of open access to researchers from all institutes in Australia, and their collaborators, in a fair and equitable manner. The ATR is administered by The University of Melbourne, which acts as custodian. Since the late 1970s the ATR has enrolled more than 40,000 twin pairs of all zygosities and facilitated more than 500 studies that have produced at least 700 peer-reviewed publications from classical twin studies, co-twin control studies, within-pair comparisons, twin family studies, longitudinal twin studies, randomized controlled trials, and epigenetics studies, as well as studies of issues specific to twins. New initiatives include: a Health and Life Style Questionnaire; data collection, management, and archiving using a secure online software program (The Ark); and the International Network of Twin Registries. The ATR's expertise and 30 years of experience in providing services to national and international twin studies has made it an important resource for research across a broad range of disciplines.
3
Townsend, G. C., T. Brown, L. C. Richards, J. R. Rogers, S. K. Pinkerton, G. R. Travan, and V. B. Burgess. "Metric Analyses of the Teeth and Faces of South Australian Twins." Acta geneticae medicae et gemellologiae: twin research 35, no. 3-4 (October 1986): 179–92. http://dx.doi.org/10.1017/s0001566000005699.
Full textAbstract:
AbstractProcedures are described for the acquisition and analysis of data in a study of the dental and facial characteristics of South Australian twins. Comparisons of the mesiodistal diameters of maxillary incisors in MZ and DZ twins revealed heterogeneity of total variances and evidence of inequality of mean values for some dimensions between MZ and DZ twins. Previous estimates of heritabilities for tooth size, relying on classical assumptions in twin research, may be exaggerated. A preliminary analysis of facial shape was undertaken using a procedure for shape matching based on a least squares fit of homologous coordinates. There was evidence of mirror-imaging in some MZ twin pairs and differences in facial asymmetry between male and female DZ twins. Future extensions of the study using methods for three-dimensional shape analysis are described.
4
Ferreira, Paulo H., Vinicius C. Oliveira, Daniela R. Junqueira, Lígia C. Cisneros, Lucas C. Ferreira, Kate Murphy, Juan R. Ordoñana, John L. Hopper, and Luci F. Teixeira-Salmela. "The Brazilian Twin Registry." Twin Research and Human Genetics 19, no. 6 (November 17, 2016): 687–91. http://dx.doi.org/10.1017/thg.2016.83.
Full textAbstract:
The Brazilian Twin Registry (BTR) was established in 2013 and has impelled twin research in South America. The main aim of the initiative was to create a resource that would be accessible to the Brazilian scientific community as well as international researchers interested in the investigation of the contribution of genetic and environmental factors in the development of common diseases, phenotypes, and human behavior traits. The BTR is a joint effort between academic and governmental institutions from Brazil and Australia. The collaboration includes the Federal University of Minas Gerais (UFMG) in Brazil, the University of Sydney and University of Melbourne in Australia, the Australian Twin Registry, as well as the research foundations CNPq and CAPES in Brazil. The BTR is a member of the International Network of Twin Registries. Recruitment strategies used to register twins have been through participation in a longitudinal study investigating genetic and environmental factors for low back pain occurrence, and from a variety of sources including media campaigns and social networking. Currently, 291 twins are registered in the BTR, with data on demographics, zygosity, anthropometrics, and health history having been collected from 151 twins using a standardized self-reported questionnaire. Future BTR plans include the registration of thousands of Brazilian twins identified from different sources and collaborate nationally and internationally with other research groups interested on twin studies.
5
Duffy, D. L., L. S. Spelman, and N. G. Martin. "Psoriasis in Australian twins." Journal of the American Academy of Dermatology 29, no. 3 (September 1993): 428–34. http://dx.doi.org/10.1016/0190-9622(93)70206-9.
Full text
6
Hay, D. A., C. Clifford, P. Derrick, J. Hopper, B. Renard, and T. M. Theobald. "Twin Children in Volunteer Registries: Biases in Parental Participation and Reporting." Acta geneticae medicae et gemellologiae: twin research 39, no. 1 (January 1990): 71–84. http://dx.doi.org/10.1017/s0001566000005584.
Full textAbstract:
AbstractThe biases in volutary participation by adult twins are well known but less attention has been paid to twin children where parents decide on participation and provide much of the information. Several aspects of reporting including the assessment of zygosity are compared in four large Australian data bases: 1) a nationwide compulsory (and hence representative) survey of literacy and numeracy; 2) a nationwide “Twins in School” survey of parents and teachers of twins run through Education Departments and AMBA, the parents organisation in conjunction with LaTrobe; 3) the LaTrobe Twin Study which is a longitudinal program involving frequent interactions between families and researchers, and 4) the Australian NHMRC Twin Registry which has surveyed a large sample of their families with twin children by mail. One potential bias comes when recruitment is on a continuing basis as in the LaTrobe Twin Study and the Australian Twin Registry when differences between “early” and “late” enrolling families arise. One difference between the four samples arose from parents being much more likely to contrast their twins and to report problems in one but not the other, whereas teachers' and psychologists' assessments of these same children generally reported much smaller intrapair differences. Future studies should have some common questions to provide comparative data on such biases. Key questions are proposed for this area, mainly on the perceived need for different forms of remediation, together with other recommendations about the minimal essential baseline data set for a registry.
7
Bennett, Kellie S., David A. Hay, Jan Piek, Jillian Pearsall-Jones, Florence Levy, and Neilson Martin. "The Australian Twin ADHD Project: Current Status and Future Directions." Twin Research and Human Genetics 9, no. 6 (December 1, 2006): 718–26. http://dx.doi.org/10.1375/twin.9.6.718.
Full textAbstract:
AbstractThis article describes the Australian Twin Attention-deficit/hyperactivity disorder (ADHD) Project (ATAP), the results of research conducted using this database and plans for future studies. Information has been actively collected from Australian families with twin children since 1991 for the ATAP database. The value of assessing siblings as well as twins is emphasized. Much work has gone into continuing the involvement of families in the study though this does become more difficult when twins reach maturity. The main focus of the project is ADHD in children and adolescents plus comorbid conditions including conduct disorder, oppositional defiant disorder, and generalized anxiety disorder. A major challenge has been how to retain continuity in the assessments, while at the same time covering changes in psychiatric classification, such as the move to Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994). Changes in the scale can affect the reports of twin similarity. Over the years, these twins have become part of other twin studies and future plans include linking different twin databases to investigate the relationships between childhood behavior and adult conditions. Recruitment, assessment and retention of twin families require a major commitment but create a significant resource for collaboration in areas outside the original aim.
8
Tyler, Jessica, Janine Lam, Katrina Scurrah, and Gillian Dite. "The Association Between Chronic Disease and Psychological Distress: An Australian Twin Study." Twin Research and Human Genetics 23, no. 6 (December 2020): 322–29. http://dx.doi.org/10.1017/thg.2020.86.
Full textAbstract:
AbstractThere is a commonly observed association between chronic disease and psychological distress, but many potential factors could confound this association. This study investigated the association using a powerful twin study design that can control for unmeasured confounders that are shared between twins, including genetic and environmental factors. We used twin-paired cross-sectional data from the Adult Health and Lifestyle Questionnaire collected by Twins Research Australia from 2014 to 2017. Linear regression models fitted using maximum likelihood estimations (MLE) were used to test the association between self-reported chronic disease status and psychological distress, measured by the Kessler Psychological Distress Scale (K6). When comparing between twin pairs, having any chronic disease was associated with a 1.29 increase in K6 (95% CI: 0.91, 1.66; p < .001). When comparing twins within a pair, having any chronic disease was associated with a 0.36 increase in K6 (95% CI: 0.002, 0.71; p = .049). This within-pair estimate is of most interest as comparing twins within a pair naturally controls for shared factors such as genes, age and shared lived experiences. Whereas the between-pair estimate does not. The weaker effect found within pairs tells us that genetic and environmental factors shared between twins confounds the relationship between chronic disease and psychological distress. This suggests that associations found in unrelated samples may show exaggerated estimates.
9
Larsen, Sally A., Callie W. Little, Katrina Grasby, Brian Byrne, Richard K. Olson, and William L. Coventry. "The Academic Development Study of Australian Twins (ADSAT): Research Aims and Design." Twin Research and Human Genetics 23, no. 3 (June 2020): 165–73. http://dx.doi.org/10.1017/thg.2020.49.
Full textAbstract:
AbstractThe Academic Development Study of Australian Twins was established in 2012 with the purpose of investigating the relative influence of genes and environments in literacy and numeracy capabilities across two primary and two secondary school grades in Australia. It is the first longitudinal twin project of its kind in Australia and comprises a sample of 2762 twin pairs, 40 triplet sets and 1485 nontwin siblings. Measures include standardized literacy and numeracy test data collected at Grades 3, 5, 7 and 9 as part of the National Assessment Program: Literacy and Numeracy. A range of demographic and behavioral data was also collected, some at multiple longitudinal time points. This article outlines the background and rationale for the study and provides an overview for the research design, sample and measures collected. Findings emerging from the project and future directions are discussed.
10
Sachdev, Perminder S., Andrea Lammel, Julian N. Trollor, Teresa Lee, Margaret J. Wright, David Ames, Wei Wen, Nicholas G. Martin, Henry Brodaty, and Peter R. Schofield. "A Comprehensive Neuropsychiatric Study of Elderly Twins: The Older Australian Twins Study." Twin Research and Human Genetics 12, no. 6 (December 1, 2009): 573–82. http://dx.doi.org/10.1375/twin.12.6.573.
Full textAbstract:
AbstractThe Older Australian Twins Study (OATS) was recently initiated to investigate genetic and environmental factors and their associations and interactions in healthy brain ageing and ageing-related neurocognitive disorders. The study extends the classic MZ-DZ design to include one or two equivalently aged siblings for each twin pair and utilizes the rich resources of the Australian Twin Registry. The study has a number of distinguishing features including comprehensive psychiatric, neuropsychological, cardiovascular, metabolic, and neuroimaging assessments, a longitudinal design and links with a brain donor program. The study measures many behavioral and environmental factors, but in particular lifetime physical and mental activity, physical and psychological trauma, loss of parent early in life, later losses and life events, early-life socioeconomic environment, alcohol and drug use, occupational exposure, and nutrition. It also includes comprehensive cardiovascular assessment, blood biochemistry, genetics and proteomics. The socio-demographic and health data on the first 172 pairs of twins participating in this study are presented. Prevalence of mild cognitive impairment is 12.8% and of dementia 1.5% in the sample. The target sample size is 1000, with at least 400 pairs of twins aged 65–90 years. The cohort will be assessed every two years, with in-depth assessments being repeated. OATS offers an excellent opportunity for collaboration with other similar studies as well as researchers who share the same interests.
11
Corfield, Elizabeth C., Nicholas G. Martin, and Dale R. Nyholt. "Familiality and Heritability of Fatigue in an Australian Twin Sample." Twin Research and Human Genetics 20, no. 3 (May 24, 2017): 208–15. http://dx.doi.org/10.1017/thg.2017.22.
Full textAbstract:
Familial factors have previously been implicated in the etiology of fatigue, of which a significant proportion is likely attributable to genetic influences. However, family studies have primarily focused on chronic fatigue syndrome, while univariate twin studies have investigated broader fatigue phenotypes. The results for similar fatigue phenotypes vary between studies, particularly with regard to sex-specific contributions to the heritability of the traits. Therefore, the current study aims to investigate the familiality and sex-specific effects of fatigue experienced over the past few weeks in an older Australian population of 660 monozygotic (MZ) twin pairs, 190 MZ singleton twins, 593 dizygotic (DZ) twin pairs, and 365 DZ singleton twins. Higher risks for fatigue were observed in MZ compared to DZ co-twins of probands with fatigue. Univariate heritability analyses indicated fatigue has a significant genetic component, with a heritability (h2) estimate of 40%. Sex-specific effects did not significantly contribute to the heritability of fatigue, with similar estimates for males (h2= 41%, 95% CI [18, 62]) and females (h2= 40%, 95% CI [27, 52]). These results indicate that fatigue experienced over the past few weeks has a familial contribution, with additive genetic factors playing an important role in its etiology.
12
Hottenga, Jouke-Jan, John B. Whitfield, Eco J. C. de Geus, Dorret I. Boomsma, and Nicholas G. Martin. "Heritability and Stability of Resting Blood Pressure in Australian Twins." Twin Research and Human Genetics 9, no. 2 (April 1, 2006): 205–9. http://dx.doi.org/10.1375/twin.9.2.205.
Full textAbstract:
AbstractIn Australian twins participating in three different studies (1979–1996), the contribution of genetic and environmental influences to variation in resting systolic (SBP) and diastolic blood pressure (DBP) was studied. The sample consisted of 368 monozygotic and 335 dizygotic twin pairs with measurements for both individuals. Blood pressure measurements in two studies were available for 115 complete twin pairs, and 49 twin pairs had measurements in three studies. This allowed assessment of blood pressure tracking over an average period of 12 years in the age range of 23 to 45 years. Multivariate analyses showed significant heritability (h2) of blood pressure in all studies (SBP h2= 19%–56%, DBP h2= 37%–52%). In addition, the analyses showed that the blood pressure tracking was explained by the same set of genetic factors. These results replicate an earlier finding in Dutch twins that also showed stability of the contribution of genetic factors to blood pressure tracking.
13
Ferreira, Lucas C., Jeffrey M. Craig, John L. Hopper, and Susan E. Carrick. "The Charles Perkins Centre's Twins Research Node." Twin Research and Human Genetics 19, no. 4 (June 15, 2016): 393–96. http://dx.doi.org/10.1017/thg.2016.44.
Full textAbstract:
Twins can help researchers disentangle the roles of genes from those of the environment on human traits, health, and diseases. To realize this potential, the Australian Twin Registry (ATR), University of Melbourne, and the Charles Perkins Centre (CPC), University of Sydney, established a collaboration to form the Twins Research Node, a highly interconnected research facility dedicated specifically to research involving twins. This collaboration aims to foster the adoption of twin designs as important tools for research in a range of health-related domains. The CPC hosted their Twins Research Node's launch seminar entitled ‘Double the power of your research with twin studies’, in which experienced twin researchers described how twin studies are supporting scientific discoveries and careers. The launch also featured twin pairs who have actively participated in research through the ATR. Researchers at the CPC were surveyed before the event to gauge their level of understanding and interest in utilizing twin research. This article describes the new Twins Research Node, discusses the survey's main results and reports on the launch seminar.
14
Mihailidis, Suzanna, Michelle Bockmann, Elise McConnell, Toby Hughes, Toos C. E. M. van Beijsterveldt, Dorret I. Boomsma, Minni McMaster, and Grant Townsend. "The Influence of Chorion Type on Health Measures at Birth and Dental Development in Australian and Dutch Twins: A Comparative Study." Twin Research and Human Genetics 18, no. 4 (July 31, 2015): 368–74. http://dx.doi.org/10.1017/thg.2015.43.
Full textAbstract:
Chorion type may significantly influence the prenatal environment of twins. This study explored the associations between chorion type and gestational age, birth weight, birth length, and the timing of emergence of the first primary tooth in two populations of twins, Australian and Dutch. Additionally, we investigated the relationship between chorion type and birth weight discordance (BWD) in order to determine whether a significant relationship existed between discordance in birth weight and discordance in the timing of emergence of the first primary tooth. The two study samples consisted of 409 Australian twin pairs and 301 Dutch twin pairs, all of European ancestry. Data were collected through a combination of questionnaires and recording charts administered to the parents and through linkage with biological databases. In the Australian sample, monozygotic monochorionic (MZMC) twins experienced the shortest mean gestation time (35 weeks), the lowest mean birth length (46 cm) and the lowest mean birth weight (2.3 kg) compared with other twin groups. For the same variables in the Dutch sample, these trends with MZMC twinning were not observed. Chorion type did not significantly affect the mean timing of emergence of the first primary tooth in either sample. Monochorionicity was found to be significantly associated with BWD in both samples, but there was a significant association between BWD in MZMC twin pairs and timing of emergence of the first primary tooth only in the Australian sample. Results from this study support previous findings that the timing of emergence of the first primary tooth is influenced strongly by genetic factors and is well protected from environmental disturbances.
15
Yang, Yuanhao, Huiying Zhao, Andrew C. Heath, Pamela A. F. Madden, Nicholas G. Martin, and Dale R. Nyholt. "Familial Aggregation of Migraine and Depression: Insights From a Large Australian Twin Sample." Twin Research and Human Genetics 19, no. 4 (June 6, 2016): 312–21. http://dx.doi.org/10.1017/thg.2016.43.
Full textAbstract:
Objectives: This research examined the familial aggregation of migraine, depression, and their co-occurrence.Methods: Diagnoses of migraine and depression were determined in a sample of 5,319 Australian twins. Migraine was diagnosed by either self-report, the ID migraine™ Screener, or International Headache Society (IHS) criteria. Depression was defined by fulfilling either major depressive disorder (MDD) or minor depressive disorder (MiDD) based on the Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria. The relative risks (RR) for migraine and depression were estimated in co-twins of twin probands reporting migraine or depression to evaluate their familial aggregation and co-occurrence.Results: An increased RR of both migraine and depression in co-twins of probands with the same trait was observed, with significantly higher estimates within monozygotic (MZ) twin pairs compared to dizygotic (DZ) twin pairs. For cross-trait analysis, the RR for migraine in co-twins of probands reporting depression was 1.36 (95% CI: 1.24–1.48) in MZ pairs and 1.04 (95% CI: 0.95–1.14) in DZ pairs; and the RR for depression in co-twins of probands reporting migraine was 1.26 (95% CI: 1.14–1.38) in MZ pairs and 1.02 (95% CI: 0.94–1.11) in DZ pairs. The RR for strict IHS migraine in co-twins of probands reporting MDD was 2.23 (95% CI: 1.81–2.75) in MZ pairs and 1.55 (95% CI: 1.34–1.79) in DZ pairs; and the RR for MDD in co-twins of probands reporting IHS migraine was 1.35 (95% CI: 1.13–1.62) in MZ pairs and 1.06 (95% CI: 0.93–1.22) in DZ pairs.Conclusions: We observed significant evidence for a genetic contribution to familial aggregation of migraine and depression. Our findings suggest a bi-directional association between migraine and depression, with an increased risk for depression in relatives of probands reporting migraine, and vice versa. However, the observed risk for migraine in relatives of probands reporting depression was considerably higher than the reverse. These results add further support to previous studies suggesting that patients with comorbid migraine and depression are genetically more similar to patients with only depression than patients with only migraine.
16
Hopper, John L., Susan A. Treloar, Nicholas H. de Klerk, and Ruth Morley. "Australian Twin Registry: A Nationally Funded Resource for Medical and Scientific Research, Incorporating match and WATCH." Twin Research and Human Genetics 9, no. 6 (December 1, 2006): 707–11. http://dx.doi.org/10.1375/twin.9.6.707.
Full textAbstract:
AbstractThe Australian Twin Registry (ATR) has, since the late 1970s, enrolled more than 30,000 pairs of all zygosity types and ages willing to consider participation in approved research studies. Its core functions are the recruitment to, and maintenance of, an up-to-date database containing contact details and baseline information, and the management of fair and equitable access so as to enhance medical and scientific research. The ATR has facilitated more than 430 studies producing 525 peer-reviewed publications using a variety of designs including classic biometrical twin and twin family studies, co-twin control studies, intervention studies, longitudinal studies, and studies of issues relevant specifically to twins. The ATR is supported for 2004 to 2009 by an Australian National Health and Medical Research Council (NHMRC) Enabling Grant, a new form of funding which recognizes the importance of long-term support for shared national resources. New initiatives include: integration with the Western Australian Twin Child Health (WATCH) cohort and the new Western Australian Twin Registry (WATR); foundation of a cohort of mothers and their twin children recruited from the time of diagnosis of the multiple gestation (match); a national Twins Festival run in collaboration with the Australian Multiple Birth Association (AMBA); promotion of the ATR at medical conferences; and fostering an active network of researchers from a range of disciplines and providing financial support for new researchers to attend international twin research workshops. Consistent with its mission statement, the long-term goal of the ATR is to make twin studies a standard component of medical and scientific research.
17
Race, Jonathan P., Grant C. Townsend, and Toby E. Hughes. "Chorion Type, Birthweight Discordance and Tooth-Size Variability in Australian Monozygotic Twins." Twin Research and Human Genetics 9, no. 2 (April 1, 2006): 285–91. http://dx.doi.org/10.1375/twin.9.2.285.
Full textAbstract:
AbstractChorion type is an important variable that can affect the prenatal environment of monozygotic (MZ) twin pairs, leading to differences in growth and development. In particular, vascular anastomoses between monochorionic (MC) MZ twin pairs can lead to an imbalance in nutrition between co-twins. One objective of this study was to determine whether maternal reports, hospital records or birthweight discordances found in MZ co-twins provide reliable indications of monochorionicity. The other objective was to test the hypotheses that in MZ twin pairs of known chorion type, MC twin pairs would show greater birthweight differences and greater within-pair variability in permanent tooth size than dichorionic (DC) twin pairs, reflecting greater differences in intrauterine environment between MC MZ pairs. Birthweights and tooth size data were recorded for 170 pairs of MZ Australian twins enrolled in an ongoing study of dentofacial growth and development. Chorion type based on maternal reports was compared with that based on hospital records for a subsample of 68 pairs of these MZ twins. Maternal reports were found to be unreliable for determining chorion type and hospital records often did not provide enough information to be certain about chorionicity. For 27 twin pairs with confirmed chorion type, associations were tested between birthweight discordances in MZ twin pairs and chorion type, and also between intrapair variances for tooth size and chorion type. A significant association was noted between birthweight discordance and chorion type (p <.05), with greater discordances occurring more often in MC twin pairs. Although significant heterogeneity of intrapair variances for tooth size was found in only 5 of 48 comparisons, intrapair variances for crown dimensions were greater significantly more often in MC pairs than DC pairs (p <.05). Our findings indicated that neither maternal reports nor often hospital records can be relied upon for information on chorion type. However, when analyses were performed on data for MZ twin pairs of known chorion type, we found evidence of a significant association between intrapair birthweight differences and chorion type and also between intrapair variances of dental crown measurements and chorion type. Consistent with our hypotheses, large birthweight discordances were found to occur more often in MC twin pairs than DC twin pairs, and intrapair variances for tooth size in MC twin pairs exceeded those in DC twin pairs more often than expected due to chance.
18
Kirk, KM, HH Maes, MC Neale, AC Heath, NG Martin, and LJ Eaves. "Frequency of church attendance in Australia and the United States: models of family resemblance." Twin Research 2, no. 2 (April 1, 1999): 99–107. http://dx.doi.org/10.1375/twin.2.2.99.
Full textAbstract:
AbstractData on frequency of church attendance have been obtained from separate cohorts of twins and their families from the USA and Australia (29 063 and 20 714 individuals from 5670 and 5615 families, respectively). The United States sample displayed considerably higher frequency of attendance at church services. Sources of family resemblance for this trait also differed between the Australian and US data, but both indicated significant additive genetic and shared environment effects on church attendance, with minor contributions from twin environment, assortative mating and parent–offspring environmental transmission. Principal differences between the populations were in greater maternal environmental effects in the US sample, as opposed to paternal effects in the Australian sample, and smaller shared environment effects observed for both women and men in the US cohort.
19
Sachdev, Perminder S., Teresa Lee, Andrea Lammel, John Crawford, Julian N. Trollor, Margaret J. Wright, Henry Brodaty, David Ames, and Nicholas G. Martin. "Cognitive functioning in older twins: The Older Australian Twins Study." Australasian Journal on Ageing 30 (October 2011): 17–23. http://dx.doi.org/10.1111/j.1741-6612.2011.00534.x.
Full text
20
Kettlewell, Nathan, and Agnieszka Tymula. "The Australian Twins Economic Preferences Survey." Twin Research and Human Genetics 24, no. 6 (December 2021): 365–70. http://dx.doi.org/10.1017/thg.2021.49.
Full textAbstract:
AbstractThis article describes the Australian Twins Economic Preferences Survey (ATEPS). The data set comprises a wide variety of preference and behavioral measures (risk aversion, impatience, ambiguity aversion, trust, confidence) elicited using incentivized decision tasks. One-thousand one-hundred twenty Australian adult twins (560 pairs) completed the survey, making it one of the largest data sets containing incentivized preference measures of twins. As the survey was conducted during the COVID-19 pandemic, we also collected information on experiences related to the pandemic, along with a variety of questions on political attitudes and mental wellbeing. We hope that ATEPS can make a valuable contribution to social science and genetics research.
21
Cutler, Tessa L., Kate Murphy, John L. Hopper, Louise A. Keogh, Yun Dai, and Jeffrey M. Craig. "Why Accurate Knowledge of Zygosity is Important to Twins." Twin Research and Human Genetics 18, no. 3 (April 8, 2015): 298–305. http://dx.doi.org/10.1017/thg.2015.15.
Full textAbstract:
All same-sex dizygotic (DZ) twins and approximately one-third of monozygotic (MZ) twin pairs have separate placentas, making it impossible to use the number of placentas to determine zygosity. Zygosity determination is further complicated because incorrect assumptions are often made, such as that only DZ pairs have two placentas and that all MZ pairs are phenotypically identical. These assumptions, by twins, their families and health professionals, along with the lack of universal zygosity testing for same-sex twins, has led to confusion within the twin community, yet little research has been conducted with twins about their understanding and assumptions about zygosity. We aimed to explore and quantify understanding and assumptions about zygosity using twins attending an Australian twin festival. We recruited 91 twin pairs younger than 18 years of age and their parents, and 30 adult twin pairs who were all uncertain of their zygosity, to complete one pen and paper questionnaire and one online questionnaire about their assumed zygosity, reasons for their assumptions and the importance of accurate zygosity knowledge. Responses were compared with their true zygosity measured using a genetic test. We found a substantial proportion of parents and twins had been misinformed by their own parents or medical professionals, and that knowledge of their true zygosity status provided peace of mind and positive emotional responses. For these reasons we propose universal zygosity testing of same-sex twins as early in life as possible and an increase in education of medical professionals, twins and families of twins about zygosity issues.
22
Baughman, H. M., E. A. Giammarco, Livia Veselka, Julie A. Schermer, Nicholas G. Martin, Michael Lynskey, and Phillip A. Vernon. "A Behavioral Genetic Study of Humor Styles in an Australian Sample." Twin Research and Human Genetics 15, no. 5 (June 13, 2012): 663–67. http://dx.doi.org/10.1017/thg.2012.23.
Full textAbstract:
The present study investigated the extent to which individual differences in humor styles are attributable to genetic and/or environmental factors in an Australian sample. Participants were 934 same-sex pairs of adult twins from the Australian Twin Registry (546 monozygotic pairs, 388 dizygotic pairs) who completed the Humor Styles Questionnaire (HSQ). The HSQ measures four distinct styles of humor — affiliative, self-enhancing, aggressive, and self-defeating. Results revealed that additive genetic and non-shared environmental factors accounted for the variance in all four humor styles, thus replicating results previously obtained in a sample of twins from the United Kingdom. However, a study conducted with a U.S. sample produced different results and we interpret these findings in terms of cross-cultural differences in humor.
23
Duffy, David L., Vijaya Manicavasagar, Dianne O'Connell, Derrick Silove, Chris Tennant, and Pauline Langelludecke. "Type A personality in Australian twins." Behavior Genetics 24, no. 5 (September 1994): 469–75. http://dx.doi.org/10.1007/bf01076182.
Full text
24
Bekkhus, Mona, Sally Staton, Anne Inger H. Borge, and Karen Thorpe. "Conflict, Closeness and Comfort: The Inter-Twin Relationship as a Risk Factor for Behavioral Difficulties." Twin Research and Human Genetics 14, no. 5 (October 1, 2011): 444–51. http://dx.doi.org/10.1375/twin.14.5.444.
Full textAbstract:
Background: There is currently little evidence concerning the impact of the inter-twin relationship on behavioral outcomes and yet the twin relationship is frequently hypothesized to be a unique source of psychopathology in twins. The current study asked whether the inter-twin relationship is a predictor of behavioral difficulties and whether there are zygosity differences in this relationship.Method: An Australian sample of same sex twins (N = 356, 164 MZ and 192 DZ) was studied in the year prior to school (Time 1) and again in first year of school (Time 2). Associations between twin-relationship and behavior problems were examined via path-analysis, and Satorra-Bentler chi-square difference tests were used to compare twins across zygosity.Results: Results show that both conflict and lower levels of warmth at Time 1 were predictive of hyperactivity and conduct disorder at Time 2, but they were not associated with emotional difficulties or peer problems. While DZ twins shared less warmth than MZ twins, there were no differences in behavior problems.Conclusion: Conflict and lower levels of warmth in the inter-twin relationship are associated with hyperactivity and conduct disorder and may serve as important considerations when making decisions regarding class separation at entry to school.
25
Hughes, Toby, Michelle Bockmann, Suzanna Mihailidis, Corinna Bennett, Abbe Harris, W. Kim Seow, Dimitra Lekkas, et al. "Genetic, Epigenetic, and Environmental Influences on Dentofacial Structures and Oral Health: Ongoing Studies of Australian Twins and Their Families." Twin Research and Human Genetics 16, no. 1 (October 12, 2012): 43–51. http://dx.doi.org/10.1017/thg.2012.78.
Full textAbstract:
The Craniofacial Biology Research Group in the School of Dentistry at The University of Adelaide is entering an exciting new phase of its studies of dental development and oral health in twins and their families. Studies of the teeth and faces of Australian twins have been continuing for nearly 30 years, with three major cohorts of twins recruited over that time, and currently we are working with twins aged 2 years old to adults. Cross-sectional data and records relating to teeth and faces of twins are available for around 300 pairs of teenage twins, as well as longitudinal data for 300 pairs of twins examined at three different stages of development, once with primary teeth, once at the mixed dentition stage, and then again when the permanent teeth had emerged. The third cohort of twins comprises over 600 pairs of twins recruited at around birth, together with other family members. The emphasis in this third group of twins has been to record the timing of emergence of the primary teeth and also to sample saliva and dental plaque to establish the timing of colonization of decay-forming bacteria in the mouth. Analyses have confirmed that genetic factors strongly influence variation in timing of primary tooth emergence. The research team is now beginning to carry out clinical examinations of the twins to see whether those who become colonized earlier with decay-forming bacteria develop dental decay at an earlier age. By making comparisons within and between monozygotic (MZ) and dizygotic (DZ) twin pairs and applying modern molecular approaches, we are now teasing out how genetic, epigenetic, and environmental factors interact to influence dental development and also oral health.
26
Beck, Jeffrey J., Jouke-Jan Hottenga, Hamdi Mbarek, Casey T. Finnicum, Erik A. Ehli, Yoon-Mi Hur, Nicholas G. Martin, Eco J. C. de Geus, Dorret I. Boomsma, and Gareth E. Davies. "Genetic Similarity Assessment of Twin-Family Populations by Custom-Designed Genotyping Array." Twin Research and Human Genetics 22, no. 4 (August 2019): 210–19. http://dx.doi.org/10.1017/thg.2019.41.
Full textAbstract:
AbstractTwin registries often take part in large collaborative projects and are major contributors to genome-wide association (GWA) meta-analysis studies. In this article, we describe genotyping of twin-family populations from Australia, the Midwestern USA (Avera Twin Register), the Netherlands (Netherlands Twin Register), as well as a sample of mothers of twins from Nigeria to assess the extent, if any, of genetic differences between them. Genotyping in all cohorts was done using a custom-designed Illumina Global Screening Array (GSA), optimized to improve imputation quality for population-specific GWA studies. We investigated the degree of genetic similarity between the populations using several measures of population variation with genotype data generated from the GSA. Visualization of principal component analysis (PCA) revealed that the Australian, Dutch and Midwestern American populations exhibit negligible interpopulation stratification when compared to each other, to a reference European population and to globally distant populations. Estimations of fixation indices (FST values) between the Australian, Midwestern American and Netherlands populations suggest minimal genetic differentiation compared to the estimates between each population and a genetically distinct cohort (i.e., samples from Nigeria genotyped on GSA). Thus, results from this study demonstrate that genotype data from the Australian, Dutch and Midwestern American twin-family populations can be reasonably combined for joint-genetic analysis.
27
Mina-Vargas, Angela, Lucía Colodro-Conde, Katrina Grasby, Gu Zhu, Scott Gordon, Sarah E. Medland, and Nicholas G. Martin. "Heritability and GWAS Analyses of Acne in Australian Adolescent Twins." Twin Research and Human Genetics 20, no. 6 (November 7, 2017): 541–49. http://dx.doi.org/10.1017/thg.2017.58.
Full textAbstract:
Acne vulgaris is a skin disease with a multifactorial and complex pathology. While several twin studies have estimated that acne has a heritability of up to 80%, the genomic elements responsible for the origin and pathology of acne are still undiscovered. Here we performed a twin-based structural equation model, using available data on acne severity for an Australian sample of 4,491 twins and their siblings aged from 10 to 24. This study extends by a factor of 3 an earlier analysis of the genetic factors of acne. Acne severity was rated by nurses on a 4-point scale (1 = absent to 4 = severe) on up to three body sites (face, back, chest) and on up to three occasions (age 12, 14, and 16). The phenotype that we analyzed was the most severe rating at any site or age. The polychoric correlation for monozygotic twins was higher (rMZ = 0.86, 95% CI [0.81, 0.90]) than for dizygotic twins (rDZ = 0.42, 95% CI [0.35, 0.47]). A model that includes additive genetic effects and unique environmental effects was the most parsimonious model to explain the genetic variance of acne severity, and the estimated heritability was 0.85 (95% CI [0.82, 0.87]). We then conducted a genome-wide analysis including an additional 271 siblings — for a total of 4,762 individuals. A genome-wide association study (GWAS) scan did not detect loci associated with the severity of acne at the threshold of 5E-08 but suggestive association was found for three SNPs: rs10515088 locus 5q13.1 (p = 3.9E-07), rs12738078 locus 1p35.5 (p = 6.7E-07), and rs117943429 locus 18q21.2 (p = 9.1E-07). The 5q13.1 locus is close to PIK3R1, a gene that has a potential regulatory effect on sebocyte differentiation.
28
Mosing, Miriam A., Nancy L. Pedersen, Nicholas G. Martin, and Margaret J. Wright. "Sex Differences in the Genetic Architecture of Optimism and Health and Their Interrelation: A Study of Australian and Swedish Twins." Twin Research and Human Genetics 13, no. 4 (August 1, 2010): 322–29. http://dx.doi.org/10.1375/twin.13.4.322.
Full textAbstract:
AbstractOptimism has a positive influence on mental and somatic health throughout lifetime and into old age. This association is mainly due to shared genetic influences, with some indication of sex differences in the heritability of these and related traits (e.g., depression and subjective wellbeing). Here we extend our initial study of Australian twins by combining with data available from Swedish twins, in order to increase the power to explore potential sex differences in the genetic architecture of optimism, mental and self-rated health and their covariation. Optimism, mental, and self-rated health were measured in 3053 Australian (501 identical female (MZf), 153 identical male (MZm), 274 non-identical female (DZf), 77 non-identical male (DZm), and 242 non-identical opposite-sex twin pairs, and 561 single twins; mean age 60.97 ± 8.76), and 812 Swedish (71 MZf, 53 MZm, 93 DZf and 67 DZm twin pairs, and 244 single twins; mean age 60 ± 14.3) twin individuals using the Life Orientation Test (LOT), the General Health Questionnaire (GHQ) and a single-item self-rating of overall health, respectively. In females all three traits were moderately heritable (.27–.47), whereas in males heritability was substantially lower (.08–.19), but genetic modeling showed that sex differences were not significant. The absence of significant sex differences, despite the consistent trend across the two cohorts, is likely due to a lack of power, raising the importance for future studies, on the same or similar traits, to utilize large samples and to keep the possibility of sex differences in mind when conducting their analyses.
29
Carvalho-e-Silva, Ana Paula, Marina B. Pinheiro, Manuela L. Ferreira, Markus Hübscher, Lucas Calais-Ferreira, and Paulo H. Ferreira. "Cohort profile: the AUstralian Twin BACK pain and physical activity study (AUTBACK study)." BMJ Open 10, no. 7 (July 2020): e036301. http://dx.doi.org/10.1136/bmjopen-2019-036301.
Full textAbstract:
PurposeDespite the growing evidence that physical activity and familial factors play a role in low back pain (LBP), there is a lack of robust longitudinal studies that (1) investigate the types and dosages of physical activity that are protective or harmful for LBP, (2) employ objective measures of physical activity and (3) conduct appropriate adjustment for confounders. The AUstralian Twin BACK (AUTBACK) study was established to elucidate the longitudinal LBP–physical activity relationship with the benefits of controlling for familial (both genetic/nongenetic) factors that may influence physical activity engagement and LBP.ParticipantsParticipants are twins registered at Twins Research Australia (TRA), older than 18 years, with access to internet. We collected data on LBP status (weekly) and physical activity levels (monthly) for 12 months as well as a wide range of health, lifestyle and physical activity (objective, self-reported, including different types and dosages) data.Findings to dateWe included 401 twins, 157 being complete twin pairs (n=314). Lifetime prevalence of LBP was 85%. Participants spent 61% of their week in sedentary time and only 4% in moderate/vigorous intensity physical activity (accelerometer). So far, 168 participants (40% of the sample) have completed the 12-month follow-up. A total of 7150 weekly (LBP status) and 1763 monthly questionnaires (physical activity status) have been answered (92% response rate).Future plansThe 12-month follow-up will be completed by June 2020. This cohort represents a novel and comprehensive resource for researchers in the field, and includes high-quality, and frequent data on LBP and physical activity. It allows the investigation of genetic and shared environmental factors on the LBP–physical activity relationship. The AUTBACK group has planned a number of projects, with the main one being the investigation of the influence of physical activity on recurrence of LBP. Data linkage opportunities are available, including with other studies conducted by TRA.
30
Schache, Maria, and Paul N. Baird. "The Australian Twin Registry as a Resource For Genetic Studies into Ophthalmic Traits." Twin Research and Human Genetics 16, no. 1 (November 2, 2012): 52–57. http://dx.doi.org/10.1017/thg.2012.96.
Full textAbstract:
The Australian Twin Registry (ATR) is a not-for-profit organization that coordinates research involving Australian twins and researchers. The ATR is one of the largest volunteer registries of its kind and contains over 33,000 twin pairs. The purpose of this review is to provide a broad overview of recent ophthalmic studies that have utilized the ATR for recruitment purposes. Such studies include the Australian Twin Eye Study (ATES) and the Genes in Myopia (GEM) study. The ATES and GEM studies have undertaken studies into the genetic influences on a number of ophthalmic traits through the use of heritability studies, linkage studies, genome-wide association studies, and candidate gene-based studies. An overview of these studies is provided in this review, as well as a description of the recruitment methodologies for both the ATES and GEM studies.
31
Dash, Genevieve F., Christal N. Davis, Nicholas G. Martin, Dixie J. Statham, Michael T. Lynskey, and Wendy S. Slutske. "High‐Intensity Drinking in Adult Australian Twins." Alcoholism: Clinical and Experimental Research 44, no. 2 (January 13, 2020): 522–31. http://dx.doi.org/10.1111/acer.14262.
Full text
32
Richards, L. C., G. C. Townsend, T. Brown, and V. B. Burgess. "Dental arch morphology in South Australian twins." Archives of Oral Biology 35, no. 12 (1990): 983–89. http://dx.doi.org/10.1016/0003-9969(90)90018-6.
Full text
33
Koncz, Rebecca, Adith Mohan, Laughlin Dawes, Anbupalam Thalamuthu, Margaret Wright, David Ames, Teresa Lee, Julian Trollor, Wei Wen, and Perminder Sachdev. "Incidental findings on cerebral MRI in twins: the Older Australian Twins Study." Brain Imaging and Behavior 12, no. 3 (July 4, 2017): 860–69. http://dx.doi.org/10.1007/s11682-017-9747-2.
Full text
34
Raj, Supriya, and Ruth Morley. "‘Are You Asking Me If We Had Sex To Conceive?’ To Whom Do Parents Of Twins Disclose Mode Of Conception and What Do They Feel About Being Asked?" Twin Research and Human Genetics 10, no. 6 (December 1, 2007): 886–91. http://dx.doi.org/10.1375/twin.10.6.886.
Full textAbstract:
AbstractThere are no data on whether parents of twins will disclose mode of conception to researchers or to their children, who will be informants in adulthood. We sent 1600 questionnaires about this via the Victorian branch of the Australian Multiple Birth Association, to be returned anonymously. Parents were asked how their twins were conceived and whether those who used assisted conception would disclose this to researchers studying assisted conception, twin pregnancy or twin children, or to their children. Comments were invited. Altogether 975 (61%) questionnaires were returned and 389 (40%) indicated use of some form of assisted conception: 75 (19%) ovarian stimulation alone, 165 (42%) In Vitro Fertilisation, 132 (34%) Intracytoplasmic Sperm Injection, and 17 (4%) Gamete Intrafallopian Transfer, with 20 reporting use of donor eggs and thirteen donor sperm. Of those using assisted conception, the proportion reporting that they would not, or may not, tell researchers was 5% for assisted conception studies, 6% for twin pregnancy studies, and 7% for studies of twin children, while 7% reported that they would not, or may not, tell their children. From the comments (from 374/975; 38%) it was clear that questions about mode of conception can be offensive to some parents of twins, unless there is a need to know. Further, the question ‘are your twins natural?’ should be avoided. We believe the question ‘Did you need medical help to conceive your twins’, followed up with specific questions, is more acceptable.
35
Metrustry, Sarah J., Mark H. Edwards, Sarah E. Medland, John W. Holloway, Grant W. Montgomery, Nicholas G. Martin, Tim D. Spector, Cyrus Cooper, and Ana M. Valdes. "Variants Close to NTRK2 Gene Are Associated With Birth Weight in Female Twins." Twin Research and Human Genetics 17, no. 4 (June 20, 2014): 254–61. http://dx.doi.org/10.1017/thg.2014.34.
Full textAbstract:
Low weight at birth has previously been shown to be associated with a number of adult diseases such as type 2 diabetes, cardiovascular disease, high blood pressure, and obesity later in life. Genome-wide association studies (GWAS) have been published for singleton-born individuals, but the role of genetic variation in birth weight (BW) in twins has not yet been fully investigated. A GWAS was performed in 4,593 female study participants with BW data available from the TwinsUK cohort. A genome-wide significant signal was found in chromosome 9, close to the NTRK2 gene (OMIM: 600456). QIMR, an Australian twin cohort (n = 3,003), and UK-based singleton-birth individuals from the Hertfordshire cohort (n = 2,997) were used as replication for the top two single nucleotide polymorphism (SNPs) underpinning this signal, rs12340987 and rs7849941. The top SNP, rs12340987, was found to be in the same direction in the Australian twins and in the singleton-born females (fixed effects meta-analysis beta = -0.13, SE = 0.02, and p = 1.48 × 10−8) but not in the singleton-born males tested. These findings provide an important insight into the genetic component of BW in twins who are normally excluded due to their lower BW when compared with singleton births, as well as the difference in BW between twins. The NTRK2 gene identified in this study has previously been associated with obesity.
36
van Beijsterveldt, C. E. M. Toos, Chantal Hoekstra, Roel Schats, Grant W. Montgomery, Gonneke Willemsen, and Dorret I. Boomsma. "Mode of Conception of Twin Pregnancies: Willingness to Reply to Survey Items and Comparison of Survey Data to Hospital Records." Twin Research and Human Genetics 11, no. 3 (June 1, 2008): 349–51. http://dx.doi.org/10.1375/twin.11.3.349.
Full textAbstract:
AbstractBased on results from a survey study in a sample of Australian parents of twins, Raj and Morley (2007) reported that questions concerning the mode of conception of twins may be offensive to parents. We looked at the willingness to reply to questions about mode of conception of twin pregnancies in a large survey study that was completed by 20,150 mothers of twins from the Netherlands Twin Registry. Data collection took place in 2005/2006. The amount of missing data was examined and by using data from earlier survey studies, responders and nonresponders were compared with respect to their answers to questions on assisted reproduction techniques. In addition, we assessed the reliability of the question on mode of conception by comparing the survey data with hospital records in a subsample of 80 mothers of twins. We found no indication that mothers of twins were not prepared to reply to questions on mode of conception. Only a small number of mothers did not fill in the question on mode of conception (0.8%). Also, the use of artificial fertility techniques did not differ between mothers who returned and mothers who did not return the 2005/2006 survey. The comparison of the survey data with the hospital records showed that mothers can accurately report on the mode of conception of their twins.
37
Higgins, Denice, Toby E. Hughes, Helen James, and Grant C. Townsend. "Strong genetic influence on hypocone expression of permanent maxillary molars in South Australian twins." Dental Anthropology Journal 22, no. 1 (September 2, 2018): 1–7. http://dx.doi.org/10.26575/daj.v22i1.83.
Full textAbstract:
An understanding of the role of genetic influences on dental traits is important in the areas of forensic odontology, human evolution and population variation. The aims of this study were: to calculate the frequency of occurrence and degree of expression of hypocones on permanent maxillary first and second molars in a sample of South Australian twins; to compare trait expression between males and females; to compare concordance rates for trait expression between monozygotic (MZ) and dizygotic (DZ) twins; and to fit genetic models to the data derived from twins and determine heritability estimates. Using stone dental casts, hypocone expression was scored on maxillary permanent first and second molars of 45 MZ twin pairs and 43 DZ pairs. Degrees of expression were scored from absence, through minor wrinkles or ridges, to very large cusps (score 0 – 5) using the standardized method of Turner et al. (1991). Hypocones were found to be more common and larger on first molars than second molars and there was a tendency for them to be larger in males although this was not statistically significant. No significant differences in occurrence or expression were noted between antimeres, with fewer differences observed between first than second molars. The percentage concordance for expression in MZ twin pairs was higher than in DZ twin pairs indicating a genetic influence determining the variation observed in hypocone expression. The most parsimonious model to explain observed variation was an AE model, incorporating additive genetic and unique environmental effects. Narrow-sense heritability estimates for both the first and second molars were high indicating that a large portion of the phenotypic variation could be explained by additive genetic effects. The greater range of phenotypic expression shown by the second molars compared with the first molars may reflect a common genetic liability that is modulated by differences in tooth size, location and/or developmental timing between these teeth.
38
Townsend, Grant, Lindsay Richards, Louise Brearley Messer, Toby Hughes, Sandra Pinkerton, Kim Seow, Theo Gotjamanos, Neville Gully, and Michelle Bockmann. "Genetic and Environmental Influences on Dentofacial Structures and Oral Health: Studies of Australian Twins and Their Families." Twin Research and Human Genetics 9, no. 6 (December 1, 2006): 727–32. http://dx.doi.org/10.1375/twin.9.6.727.
Full textAbstract:
AbstractOur studies of the teeth and faces of Australian twins commenced at the School of Dentistry, The University of Adelaide in the early 1980s. There are now over 900 pairs of twins enrolled in our continuing investigations, together with 1200 relatives. There are 3 main cohorts of participants. The first cohort comprises around 300 pairs of teenage twins for whom various records have been collected, including dental casts, facial photographs, finger and palm prints and information on laterality, including handedness. The second cohort comprises around 300 pairs of twins who have been examined at 3 stages of dental development from approximately 4 years of age to about 14 years: at primary, mixed, and permanent dentition (excluding 3rd molars) stages. The most recent study of tooth emergence and oral health, for which we are currently recruiting twins, will provide a third cohort of around 500 twin pairs aged from around birth to 3 to 4 years of age. Our broad aim in these studies has been to improve our understanding of how genetic and environmental factors contribute to variation in dental and facial features, and to oral health. We have also used our data to investigate aspects of the determination of laterality, particularly the fascinating phenomenon of mirror imaging. We plan to maximize the use of the longitudinal data and DNA we have collected, and continue to collect, by performing genome-wide scans for putative genetic linkage peaks for a range of dental features, and then to test for association between a series of likely candidate genes and our phenotypes.
39
Waldron, Mary, Andrew C. Heath, Eric Turkheimer, Robert Emery, Kathleen K. Bucholz, Pamela A. F. Madden, and Nicholas G. Martin. "Age at First Sexual Intercourse and Teenage Pregnancy in Australian Female Twins." Twin Research and Human Genetics 10, no. 3 (June 1, 2007): 440–49. http://dx.doi.org/10.1375/twin.10.3.440.
Full textAbstract:
AbstractGirls who report first sexual intercourse during their early teen years have much higher rates of teenage pregnancy and childbearing than girls who delay sexual onset until older adolescence. In this study, we examine genetic and environmental influences on variation in teenage pregnancy and covariation with age at first sexual intercourse in two cohorts of Australian female twins. In the older twin cohort, born 1893–1964, we observe substantial heritable variation in teenage pregnancy that is largely shared with heritable variation in age at first sexual intercourse, with shared environment contributintablg little to variation in teenage pregnancy. Genetic influences on teenage pregnancy are smaller and nonsignificant in the younger twin cohort, born 1964–1971, where shared environment contributes much more and overlaps entirely with shared environmental variation in age at first intercourse.
40
Verhulst, Brad, Michael C. Neale, Lindon J. Eaves, Sarah E. Medland, Andrew C. Heath, Nicholas G. Martin, and Hermine H. Maes. "Extended Twin Study of Alcohol Use in Virginia and Australia." Twin Research and Human Genetics 21, no. 3 (April 25, 2018): 163–78. http://dx.doi.org/10.1017/thg.2018.21.
Full textAbstract:
Drinking alcohol is a normal behavior in many societies, and prior studies have demonstrated it has both genetic and environmental sources of variation. Using two very large samples of twins and their first-degree relatives (Australia ≈ 20,000 individuals from 8,019 families; Virginia ≈ 23,000 from 6,042 families), we examine whether there are differences: (1) in the genetic and environmental factors that influence four interrelated drinking behaviors (quantity, frequency, age of initiation, and number of drinks in the last week), (2) between the twin-only design and the extended twin design, and (3) the Australian and Virginia samples. We find that while drinking behaviors are interrelated, there are substantial differences in the genetic and environmental architectures across phenotypes. Specifically, drinking quantity, frequency, and number of drinks in the past week have large broad genetic variance components, and smaller but significant environmental variance components, while age of onset is driven exclusively by environmental factors. Further, the twin-only design and the extended twin design come to similar conclusions regarding broad-sense heritability and environmental transmission, but the extended twin models provide a more nuanced perspective. Finally, we find a high level of similarity between the Australian and Virginian samples, especially for the genetic factors. The observed differences, when present, tend to be at the environmental level. Implications for the extended twin model and future directions are discussed.
41
Gillespie, Nathan A., Anjali K. Henders, Tracy A. Davenport, Daniel F. Hermens, Margie J. Wright, Nicholas G. Martin, and Ian B. Hickie. "The Brisbane Longitudinal Twin Study: Pathways to Cannabis Use, Abuse, and Dependence Project—Current Status, Preliminary Results, and Future Directions." Twin Research and Human Genetics 16, no. 1 (November 28, 2012): 21–33. http://dx.doi.org/10.1017/thg.2012.111.
Full textAbstract:
We describe the data being collected from the Brisbane Longitudinal Twin Study in Australia as part of the US National Institute on Drug Abuse (NIDA)-funded project, Pathways to Cannabis Use, Abuse and Dependence. The history, recruitment, assessment, and retention of twin families in this project are described in detail, along with preliminary findings and plans for future research. The goal of this NIDA project is to make a significant contribution to the discovery of quantitative trait loci influencing cannabis use disorders. Although the focus is cannabis use, abuse, and dependence in young adults, measures of comorbid illicit drug use disorders are also being collected. In addition, a variety of internalizing and externalizing disorders are being assessed, funded by support from the Australian National Health and Medical Research Council. Because these same twins have participated in numerous twin studies since 1992, future plans will include linking different phenotypes to investigate relationships between drug use, psychiatric disorders, and psychological phenotypes within cross-sectional and longitudinal or developmental frameworks.
42
Couvy-Duchesne, Baptiste, Victoria O’Callaghan, Richard Parker, Natalie Mills, Katherine M. Kirk, Jan Scott, Anna Vinkhuyzen, et al. "Nineteen and Up study (19Up): understanding pathways to mental health disorders in young Australian twins." BMJ Open 8, no. 3 (March 2018): e018959. http://dx.doi.org/10.1136/bmjopen-2017-018959.
Full textAbstract:
PurposeThe Nineteen and Up study (19Up) assessed a range of mental health and behavioural problems and associated risk factors in a genetically informative Australian cohort of young adult twins and their non-twin siblings. As such, 19Up enables detailed investigation of genetic and environmental pathways to mental illness and substance misuse within the Brisbane Longitudinal Twin Sample (BLTS).ParticipantsTwins and their non-twin siblings from Queensland, Australia; mostly from European ancestry. Data were collected between 2009 and 2016 on 2773 participants (age range 18–38, 57.8% female, 372 complete monozygotic pairs, 493 dizygotic pairs, 640 non-twin siblings, 403 singleton twins).Findings to dateA structured clinical assessment (Composite International Diagnostic Interview) was used to collect lifetime prevalence of diagnostic statistical manual (4th edition) (DSM-IV) diagnoses of major depressive disorder, (hypo)mania, social anxiety, cannabis use disorder, alcohol use disorder, panic disorder and psychotic symptoms. Here, we further describe the comorbidities and ages of onset for these mental disorders. Notably, two-thirds of the sample reported one or more lifetime mental disorder.In addition, the 19Up study assessed general health, drug use, work activity, education level, personality, migraine/headaches, suicidal thoughts, attention deficit hyperactivity disorder (ADHD) symptomatology, sleep–wake patterns, romantic preferences, friendships, familial environment, stress, anorexia and bulimia as well as baldness, acne, asthma, endometriosis, joint flexibility and internet use.The overlap with previous waves of the BLTS means that 84% of the 19Up participants are genotyped, 36% imaged using multimodal MRI and most have been assessed for psychological symptoms at up to four time points. Furthermore, IQ is available for 57%, parental report of ADHD symptomatology for 100% and electroencephalography for 30%.Future plansThe 19Up study complements a phenotypically rich, longitudinal collection of environmental and psychological risk factors. Future publications will explore hypotheses related to disease onset and development across the waves of the cohort. A follow-up study at 25+years is ongoing.
43
Condon, Julianne, Joanne E. Shaw, Michelle Luciano, Kirsten O. Kyvik, Nicholas G. Martin, and David L. Duffy. "A Study of Diabetes Mellitus Within a Large Sample of Australian Twins." Twin Research and Human Genetics 11, no. 1 (February 1, 2008): 28–40. http://dx.doi.org/10.1375/twin.11.1.28.
Full textAbstract:
AbstractTwin studies of diabetes mellitus can help elucidate genetic and environmental factors in etiology and can provide valuable biological samples for testing functional hypotheses, for example using expression and methylation studies of discordant pairs. We searched the volunteer Australian Twin Registry (19,387 pairs) for twins with diabetes using disease checklists from nine different surveys conducted from 1980–2000. After follow-up questionnaires to the twins and their doctors to confirm diagnoses, we eventually identified 46 pairs where one or both had type 1 diabetes (T1D), 113 pairs with type 2 diabetes (T2D), 41 female pairs with gestational diabetes (GD), 5 pairs with impaired glucose tolerance (IGT) and one pair with MODY. Heritabilities of T1D, T2D and GD were all high, but our samples did not have the power to detect effects of shared environment unless they were very large. Weight differences between affected and unaffected cotwins from monozygotic (MZ) discordant pairs were large for T2D and GD, but much larger again for discordant dizygotic (DZ) pairs. The bivariate genetic analysis (under the multifactorial threshold model) estimated the genetic correlation between body mass index (BMI) and T2D to be 0.46, and the environmental correlation at only 0.06.
44
Bockmann, Michelle R., Toby E. Hughes, and Grant C. Townsend. "Genetic Modeling of Primary Tooth Emergence: A Study of Australian Twins." Twin Research and Human Genetics 13, no. 6 (December 1, 2010): 573–81. http://dx.doi.org/10.1375/twin.13.6.573.
Full textAbstract:
The aim of this study was to quantify contributions of genetic and environmental factors to variation in timing of emergence of the primary teeth in a sample of monozygotic and dizygotic twins, using univariate model-fitting approaches. The sample comprised 94 pairs of monozygotic twins and 125 pairs of dizygous twins, all of European ancestry, aged from 2–6 years. Tooth emergence timing was based on parental report, with a subset of data validated by clinical assessment. Heritability estimates for tooth emergence timing were generally high, around 90%, however estimates for the lower right lateral incisor and the lower canines were around 50%. These findings confirm a strong genetic influence on observed variation in the timing of emergence of the human primary teeth.
45
Schermerhorn, Alice C., Brian M. D'Onofrio, Wendy S. Slutske, Robert E. Emery, Eric Turkheimer, K. Paige Harden, Andrew C. Heath, and Nicholas G. Martin. "Offspring ADHD as a Risk Factor for Parental Marital Problems: Controls for Genetic and Environmental Confounds." Twin Research and Human Genetics 15, no. 6 (September 10, 2012): 700–713. http://dx.doi.org/10.1017/thg.2012.55.
Full textAbstract:
Background: Previous studies have found that child attention-deficit/hyperactivity disorder (ADHD) is associated with more parental marital problems. However, the reasons for this association are unclear. The association might be due to genetic or environmental confounds that contribute to both marital problems and ADHD. Method: Data were drawn from the Australian Twin Registry, including 1,296 individual twins, their spouses, and offspring. We studied adult twins who were discordant for offspring ADHD. Using a discordant twin pairs design, we examined the extent to which genetic and environmental confounds, as well as measured parental and offspring characteristics, explain the ADHD–marital problems association. Results: Offspring ADHD predicted parental divorce and marital conflict. The associations were also robust when comparing differentially exposed identical twins to control for unmeasured genetic and environmental factors, when controlling for measured maternal and paternal psychopathology, when restricting the sample based on timing of parental divorce and ADHD onset, and when controlling for other forms of offspring psychopathology. Each of these controls rules out alternative explanations for the association. Conclusion: The results of the current study converge with those of prior research in suggesting that factors directly associated with offspring ADHD increase parental marital problems.
46
Mitchell, Brittany L., Adrian I. Campos, Miguel E. Rentería, Richard Parker, Lenore Sullivan, Kerrie McAloney, Baptiste Couvy-Duchesne, et al. "Twenty-Five and Up (25Up) Study: A New Wave of the Brisbane Longitudinal Twin Study." Twin Research and Human Genetics 22, no. 03 (June 2019): 154–63. http://dx.doi.org/10.1017/thg.2019.27.
Full textAbstract:
AbstractThe aim of the 25 and Up (25Up) study was to assess a wide range of psychological and behavioral risk factors behind mental illness in a large cohort of Australian twins and their non-twin siblings. Participants had already been studied longitudinally from the age of 12 and most recently in the 19Up study (mean age = 26.1 years, SD = 4.1, range = 20–39). This subsequent wave follows up these twins several years later in life (mean age = 29.7 years, SD = 2.2, range = 22–44). The resulting data set enables additional detailed investigations of genetic pathways underlying psychiatric illnesses in the Brisbane Longitudinal Twin Study (BLTS). Data were collected between 2016 and 2018 from 2540 twins and their non-twin siblings (59% female, including 341 monozygotic complete twin-pairs, 415 dizygotic complete pairs and 1028 non-twin siblings and singletons). Participants were from South-East Queensland, Australia, and the sample was of predominantly European ancestry. The 25Up study collected information on 20 different mental disorders, including depression, anxiety, substance use, psychosis, bipolar and attention-deficit hyper-activity disorder, as well as general demographic information such as occupation, education level, number of children, self-perceived IQ and household environment. In this article, we describe the prevalence, comorbidities and age of onset for all 20 examined disorders. The 25Up study also assessed general and physical health, including physical activity, sleep patterns, eating behaviors, baldness, acne, migraines and allergies, as well as psychosocial items such as suicidality, perceived stress, loneliness, aggression, sleep–wake cycle, sexual identity and preferences, technology and internet use, traumatic life events, gambling and cyberbullying. In addition, 25Up assessed female health traits such as morning sickness, breastfeeding and endometriosis. Furthermore, given that the 25Up study is an extension of previous BLTS studies, 86% of participants have already been genotyped. This rich resource will enable the assessment of epidemiological risk factors, as well as the heritability and genetic correlations of mental conditions.
47
NELSON, ELLIOT C., ANDREW C. HEATH, MICHAEL T. LYNSKEY, KATHLEEN K. BUCHOLZ, PAMELA A. F. MADDEN, DIXIE J. STATHAM, and NICHOLAS G. MARTIN. "Childhood sexual abuse and risks for licit and illicit drug-related outcomes: a twin study." Psychological Medicine 36, no. 10 (July 20, 2006): 1473–83. http://dx.doi.org/10.1017/s0033291706008397.
Full textAbstract:
Background. This study examined the relationships between self-reported childhood sexual abuse (CSA) and drug-related outcomes in an Australian twin panel.Method. A semi-structured psychiatric interview was conducted in 1996–2000 by telephone with young adult Australian twins (mean age 29·9 years). Data reported here are from 6050 twins who responded to both CSA and drug-related items.Results. A history of CSA was associated with significant risk for subsequently occurring regular smoking and use of each illicit drug class. Further CSA-associated risk was found among regular users, for nicotine and alcohol dependence, and among illicit drug users, for abuse/dependence of most drug classes. In same-sex discordant pairs, significant risk for regular smoking and illicit drug use was found in twins with a history of CSA compared to their non-abused co-twins. Similar analyses for abuse/dependence found significant risk for opioids, any illicit drug, and any non-cannabis illicit drug. CSA was associated with significantly earlier drug use. Despite the association of CSA with risk for early-onset cannabis use and regular smoking, risks for illicit drug outcomes associated with CSA and with either form of early-onset use combine in near-additive fashion.Conclusions. CSA is associated with risk for subsequently occurring regular smoking and illicit drug use and abuse/dependence. Risks for drug use are mildly attenuated with control for familial contributions; similar risks for abuse/dependence remain significant for opioids and for illicit drugs combined across classes. Although we found evidence of earlier onset drug use with CSA, risks associated with CSA and with early-onset use combine in a largely additive manner.
48
Hopper, J. L., V. M. White, G. T. Macaskill, D. J. Hill, and C. A. Clifford. "Alcohol Use, Smoking Habits and the Junior Eysenck Personality Questionnaire in Adolescent Australian Twins." Acta geneticae medicae et gemellologiae: twin research 41, no. 4 (October 1992): 311–24. http://dx.doi.org/10.1017/s0001566000002166.
Full textAbstract:
AbstractIn 1988, questionnaires were received from 1,400 twin pairs (17% MZM, 23% MZF, 17% DZM, 19% DZF, 24% DZO) aged 11 to 18, registered with the Australian NHMRC Twin Registry. Twins reported independently on themselves and on the perceived behaviour of their parents, siblings and friends. For smoking and for drinking in the previous month, the prevalence was modelled as a logistic function of age, sex, perceived smoking or drinking behaviour of family and friends, and the Junior Eysenck Personality Questionnaire (JEPQ) scales. Strenghts of association were: family behaviour, odds ratio (OR) ≤2; Extraversion and Psychoticism, interquartile OR ≈ 1.6; behaviour of friend, OR ≈ 3 to 6. Twin associations were represented by odds ratios. For smoking they were 16 in MZ and 7 in DZ same-sex pairs, and 3 in DZO pairs. Although the former is consistent with genetic factors determining adolescent smoking behaviour, the reduced association in DZO pairs and strong association with smoking by friends argue to the contrary. For drinking, twin odds ratios were 11 in MZM, MZF and DZF pairs, and 4 in DZM and DZO pairs, consistent with genetic factors determining alcohol use in male but not female, adolescents. Twin odds ratios were not influenced by adjustment for the JEPQ scales; this does not support the hypothesis that genetic factors which determine personality also determine smoking or drinking behaviour during adolescence.
49
Matison, Annabel, Anbupalam Thalamuthu, Simone Reppermund, Victoria Flood, Julian Trollor, Margaret Wright, David Ames, Henry Brodaty, Perminder Sachdev, and Karen Mather. "Nature Versus Nurture – Studying the Relationships Between Diet and Depression in Older Adults." Current Developments in Nutrition 6, Supplement_1 (June 2022): 1118. http://dx.doi.org/10.1093/cdn/nzac078.012.
Full textAbstract:
Abstract Objectives Prior work suggests that higher fruit and vegetable consumption may protect against depression in older adults. By better understanding the influence of genetic and environmental factors on fruit and vegetable intakes, more effective interventions could be designed to increase intakes in older adults to reduce and/or assist with the treatment of depression in older adults. The aim of this heritability study is to estimate the genetic and environmental influences on the consumption of fruit and vegetables in older adults and to investigate if there are shared influences between fruit and vegetable intakes and depression. Methods Participants (n = 374 twins, 67.1% female; 208 identical; 166 non-identical, ≥ 65-years) were drawn from the Older Australian Twins Study. Data on diet (validated food frequency questionnaire) and depressive symptoms (15-item Geriatric Depression Scale) were collected. The contribution of genetic and environmental influences on fruit and vegetable intake were estimated by comparing identical and non-identical twin intakes using structural equation modelling. A trivariate model was used to estimate the genetic and environmental correlation between total fruit and vegetable intakes and depression. Results In this study, vegetable intake was moderately influenced by genetics (heritability = 36%) with the remaining 64% due to the unique environment. Heritability was highest for brassica vegetables (40%), while intake of starchy vegetables was not heritable. Genetics did not significantly influence the intake of fruit. No significant genetic or environmental correlations were detected between fruit or vegetable intakes and depression. The number of participants meeting Australian Dietary Guidelines for fruit and vegetable intake was low (fruit 46.5%; vegetables 2.9%). Conclusions Consumption of vegetables, particularly bitter tasting brassica vegetables, was significantly influenced by genetics. These findings provide novel insights into the drivers of fruit and vegetable consumption in older adults and may help shape interventions to increase intakes, with the view of reducing the burden of depression. Funding Sources The Older Australian Twins Study was funded by the National Health & Medical Research Council and Australian Research Council.
50
Lam, Janine R., Jessica Tyler, Katrina J. Scurrah, Nicola J. Reavley, and Gillian S. Dite. "The Association between Socioeconomic Status and Psychological Distress: A Within and Between Twin Study." Twin Research and Human Genetics 22, no. 5 (October 2019): 312–20. http://dx.doi.org/10.1017/thg.2019.91.
Full textAbstract:
AbstractLow socioeconomic status (SES) has been established as a risk factor for poor mental health; however, the relationship between SES and mental health problems can be confounded by genetic and environmental factors in standard regression analyses and observational studies of unrelated individuals. In this study, we used a within-pair twin design to control for unmeasured genetic and environmental confounders in investigating the association between SES and psychological distress. We also employed within–between pair regression analysis to assess whether the association was consistent with causality. SES was measured using the Index of Relative Socio-economic Disadvantage (IRSD), income and the Australian Socioeconomic Index 2006 (AUSEI06); psychological distress was measured using the Kessler 6 Psychological Distress Scale (K6). Data were obtained from Twins Research Australia’s Health and Lifestyle Questionnaire (2014–2017), providing a maximum sample size of 1395 pairs. Twins with higher AUSEI06 scores had significantly lower K6 scores than their co-twins after controlling for shared genetic and environmental traits (βW [within-pair regression coefficient] = −0.012 units, p = .006). Twins with higher income had significantly lower K6 scores than their co-twins after controlling for familial confounders (βW = −0.182 units, p = .002). There was no evidence of an association between the IRSD and K6 scores within pairs (βW, p = .6). Using a twin design to eliminate the effect of potential confounders, these findings further support the association between low SES and poor mental health, reinforcing the need to address social determinants of poor mental health, in addition to interventions targeted to individuals.