The feasibility of creating a population-based national twin registry in the United States.

Between 4 to 6 million twins exist in the US today who offer scientists a valuable potential resource for conducting behavioral and biomedical research. However, unlike many other countries, there is no national system in the US for identifying twins and eliciting their participation in these important research programs. Therefore, the National Institute of Environmental Health Sciences (NIEHS) is conducting a study to determine the feasibility of creating a national, population-based twin registry in the US. The major goal is to estimate the potential size and characteristics of a national twin registry based on the current twin population in the US, our ability to ascertain and enroll them, and their willingness to participate. Existing US twin cohorts are also being examined in this study as well as alternatives for improving US twin resources should a national twin registry be deemed infeasible. The various options will be compared in terms of possible source populations, generalizability and adequacy for statistically powering various types of etiological studies. Two expert advisory panels have been assembled to assist in the conduct of this study. The Scientific Advisory Panel is charged with providing expertise concerning study goals, design and methodology, and evaluating the study's conclusion. A separate Ethics Advisory Panel is charged with providing expertise on the ethical, legal, and social issues that might be encountered if a national twin registry is ultimately pursued. Having a national population-based twin registry in the US would be advantageous to US scientists and those worldwide. It would provide ample numbers of twin pairs to conduct various types of environmental genomic studies currently not possible with existing US twin resources. It would also allow US scientists to select for characteristics (race, ethnicity, environments, and so on) inherent in our own population. Finally and foremost, it would help to meet the worldwide demand for twin resources which is expected to increase over time, as new genomic and analytical tools become available and new hypotheses emerge concerning the complex interplay between genes, lifestyles and environment.

Healthy Twin: a twin-family study of Korea--protocols and current status.

"Healthy Twin" is a twin family study extension of the existing Korean Twin-Family Register. Healthy Twin recruits adult like-sex twins over the age of 30 and their adult family members. Healthy Twin protocols are primarily tailored to the study of the quantitative trait loci of complex traits as well as to the role of environment in the etiology of complex diseases. A full-length survey is underway, including questionnaires, health examinations and the collection of biological specimens. So far, 820 individuals (169 twin pairs and their families) have participated in the survey and 1068 individual twins (608 twin pairs) have replied to the mailed zygosity questionnaire as of July 2006. The first phase (2005-2006) of Healthy Twin will recruit 1550 individuals (including about 380 twin pairs), and the second phase a proposed 1500 to 2500 additional participants. We report study protocols and zygosity and the distribution of family size of the study participants.

HealthTwiSt: the Berlin Twin Registry.

The Berlin Twin Registry began as a short-term local project and developed into a resource that now serves partners throughout Germany and Europe. A twin registry as a private company is a different approach with pros and cons. Compared to academic institutions, there are greater flexibilities in collaborations, as well as acquisition and use of research funds. Recruitment is based on invitation in the context of the mass media coverage of scientific results. Phenotyping in normal twin subjects is concentrated on intermediate phenotypes that can bear on common diseases. These phenotypes include proteomic approaches and gene expression. Some results are briefly described to give an impression of the range of research topics and related opportunities for retrospective and prospective collaborative research.

An initiative in Spain for the study of women's health: the Murcia Twin Registry.

The present article describes the initial steps taken in setting up a twin registry in Spain. The Murcia Twin Registry (MTR) will focus initially on perimenopausal women's health. It will be administered and managed by the University of Murcia and the Murcia Health Council and will start with a database of 452 pairs of female twins born between 1940 and 1965 in the region of Murcia, Spain. Once the MTR is established and has gained some experience, our goal is to expand the age range and include males and opposite-sex twins. The current main areas of research interest are menopause, preventive behaviors, lifestyle and health as well as quality of life.

The Italian Twin Register: new cohorts and tools, current projects and future perspectives of a developing resource.

Since its start as a database of "possible twins", the Italian Twin Register has developed remarkably in terms of twin approach and recruitment, data-management tools, the cohorts enrolled, and the breadth of information gathered, making the Italian Twin Register a valuable resource for genetic epidemiological research. The Italian Twin Register is a random population of twins at both the national level and within targeted geographical areas or birth cohorts. Further, the Register is linked with disease records and has recently implemented a web-based method for volunteer twin recruitment specifically designed to promote the Register and to disseminate information on genetic epidemiology. To date, approximately 9000 twins have joined the Italian Twin Register, the majority of whom (approximately 70%) represent young adults aged 20 at time of enrollment. Although the total number of twins recruited to date is far below the expected figure initially predicted, the newly established standardized procedures guarantee an increase of around 2000 twins each year. Following the collaboration between the Italian Twin Register and the main Italian nonprofit association for blood donors, twin DNA sampling and storage has recently accelerated contributing to the large amount of phenotypic data collected. The Italian Twin Register is currently involved in both population and clinical based studies on various complex phenotypes and diseases, some conducted within large European consortia.

Twin database of the secondary school attached to the Faculty of Education of the University of Tokyo.

This article profiles the historical twin databases of the secondary education school attached to the Faculty of Education at the University of Tokyo. The school was established in 1948. Every year, about 50 pairs of twins of all sex and zygosity combinations and aged 11 to 12 years take an examination, and about 10 to 20 pairs are admitted based on the results. Three independent datasets exist: one for applicants (11-12 years), one for students (12-18 years), and one for graduates (18-72 years). These three historical databases and research perspectives are introduced herein.

The Norwegian Institute of Public Health twin program of research: an update.

The population-based twin program of research at the Norwegian Institute of Public Health (NIPH) was begun in 1992. It consists of a number of questionnaire and clinical interview projects exploring a broad array of mental and physical health outcomes. This article provides a brief update summarizing our research activities, some research highlights, new developments and potentials for further developing the program of twin research. In the most recent years a large effort has concentrated on completing a mental health interview study of Axis I psychiatric and substance use disorders and Axis II personality disorders. Although still in the early planning phases, one of the most significant developments is that an agreement is now in place to centralize the Norwegian twin data into a national Norwegian Twin Registry. This new registry will include twin cohorts born from 1905 onwards. Other resources for building twin projects are described. Nationally, there is great potential for linking the NIPH twin data with other health registries and with information in a number of Norway's large population-based biobank studies. Internationally, platforms such as those developed within GenomEUtwin, for data standards and data sharing and access are greatly facilitating international collaborations in twin research.