CATSS9w - The Child and Adolescent Twin Study in Sweden (9 year, web questionnaire)

Only the autism section of the A-TAC questionnaire, used in CATSS9 (see separate data description), is used here. DOI: 10.1192/bjp.187.3.262 DOI: 10.1186/1471-244X-10-1 DOI: 10.1186/1471-244X-13-233

Screening of ADHD based on the DSM-IV Criteria. DOI: 10.1176/appi.books.9780890420249.dsm-iv-tr

The Life Stressor Checklist-Revised (LSC-R) is a self-report measure used to assess traumatic or stressful life events. DOI: 10.1017/S0033291711003060 DOI: 10.1037/t04534-000

Approved on 4th of March 2020

The Swedish Twin Registry (STR) is a national research register open to academic and industrial users. The mission of the STR is to provide a longitudinal research resource for epidemiological and molecular studies of twins. It was originally established in 1959 with particular focus on cardiovascular disease and cancer. Since then, interest has expanded to almost all common diseases and health problems. The STR has contacted all living Swedish born twins (over 9 years) and is the world´s largest twin registry. The current system of twin ascertainment, which has been running in perpetual mode for 13 years, is done through parental interviews when the twins turn 9 years of age. Nationwide questionnaires and telephone interviews have been conducted for different birth cohorts since the beginning of the 1960s. Longitudinal information about health and disease is obtained through regular linkages to the Swedish health registries. DNA from 55 000 twins and serum of 13 000 twins are stored at KI Biobank and is subject to use to new investigations and analyses. Genome-wide genotyping of more than 30 000 participants has been completed and genotypes can be used for co-analysis for different outcomes and characteristics. We apply for funds to keep up the register, continue the ascertainment of 9-year old twins and introduce, in parallel, a nation-wide system for ascertainment of new-born twins with concomitant sampling of umbilical cord blood and immediate zygosity testing.

We apply for a continuation of the support of the Swedish Twin Registry (STR), a research infrastructure for population based, epidemiological and molecular studies of twins. The purpose of the STR is to enable research about the importance of genetic and environmental factors for health, lifestyle and behavior.The STR facilitates access to data, samples and twin-contacts for de novo data-collection. For more than 60 years, it has been used for research on a large number of diseases, behaviors and health problems. All living Swedish born twins over the age of 9 years have been contacted by the STR and it is thereby the largest twin registry in the world.Nationwide questionnaires, measurements and telephone interviews have been conducted for different birth cohorts since the 1960s. Broad consents and a unified system make it possible to combine data and samples over the sub-studies to address new research questions. Beside self-reported health and exposures, additional critical information is obtained through regular linkages to the national health registers. At present, the STR holds DNA and other biological samples from more than 58 000 twins to be used for new analyses. Genome-wide genotyping is available for the vast majority.The STR is managed by Karolinska Institutet and led by a Steering Group with mandate for periods of 3 years. There is also an advisory National Council with members from several universities that meets two times per year. It provides an academic arena for input and communication regarding strategies impacting the research enabled by the STR in the future. The grant will support the running costs of the new twin contacts, sample and data collections, upholding the secure database and provide access to data for researchers. The national added value consists in the opportunity to manage and develop an already productive infrastructure in directions that benefits a national range of researchers in a cross disciplinary and transparent manner.