Swedish Twin Registry

Swedish Twin Registry is a national population-based twin register established in Sweden to support longitudinal research in genetics, epidemiology, and public health. The registry links twin pairs to Swedish national registers and has been used in studies involving Charles Darwin, Francis Galton, Gregor Mendel, Thomas Hunt Morgan, and contemporary scholars from institutions such as Karolinska Institutet, Uppsala University, and Lund University. It collaborates with international consortia including the International Society for Twin Studies, the Consortium for Genetics of Personality Traits, and the Cohorts for Heart and Aging Research in Genomic Epidemiology.

History

The registry traces conceptual roots to early twin studies by Francis Galton and theoretical frameworks from Charles Darwin; formal organization began amid mid‑20th century efforts in Nordic epidemiology influenced by researchers at Karolinska Institutet and Uppsala University. Initial waves of data collection in the 1960s and 1970s coincided with registry developments at Danish Twin Registry and Finnish Twin Cohort, and expansion accelerated with linkage to Swedish national resources like the Swedish National Board of Health and Welfare registers and the Total Population Register (Sweden). Major methodological contributions have been disseminated in journals associated with The Lancet, Nature Genetics, and American Journal of Human Genetics.

Structure and Cohorts

The registry comprises multiple subcohorts assembled by birth year, zygosity, and participation in surveys or clinical examinations. Core cohorts include twins born in 1886–1925, 1926–1958, and later birth cohorts covering 1959 onward, with specialized samples for aging studies, psychiatric research, and cardiovascular investigations. Administrative and research governance involve institutions such as Karolinska Institutet, Uppsala University, Stockholm University, and regional health authorities like the Stockholm County Council. Collaborative links extend to biobanks including SciLifeLab and international projects with groups affiliated to Harvard University, University of Oxford, and University of California, Los Angeles.

Data Collection and Variables

Data sources integrate questionnaire surveys, clinical examinations, registry linkages, and biospecimens. Variables include zygosity assessments, biometric measures, clinical diagnoses coded to classifications from World Health Organization, medication records from the Swedish Prescribed Drug Register, cause‑of‑death information from the Cause of Death Register (Sweden), and sociodemographic data from the Longitudinal Integration Database for Health Insurance and Labour Market Studies. Genetic data generated in collaboration with genotyping centers tied to Wellcome Trust Sanger Institute, Broad Institute, and European Bioinformatics Institute enable genome‑wide association analyses. Mental health phenotypes have been harmonized with instruments used in cohorts linked to National Institute of Mental Health, while cardiovascular endpoints align with protocols from European Society of Cardiology studies.

Research Uses and Key Findings

Researchers have exploited the registry for classical twin designs, discordant twin analyses, and modern molecular twin studies. Notable domains include heritability estimates for traits studied in meta‑analyses with groups from University of Cambridge, Columbia University, and Yale University; gene–environment interaction research coordinated with teams at Max Planck Institute for Psycholinguistics and University of Chicago; and longitudinal aging research integrated with projects at University College London and Johns Hopkins University. Key findings include refined heritability estimates for psychiatric disorders published alongside consortia such as the Psychiatric Genomics Consortium, insights into genetic and environmental contributions to cardiovascular risk factors corroborated by Framingham Heart Study comparisons, and evidence on life‑course influences on mortality consistent with work from Helsinki University Hospital cohorts. The registry has also informed studies on educational attainment, linking results to international efforts at University of Oxford and Stanford University.

Governance, Ethics, and Access

Governance frameworks involve ethical review boards associated with Swedish Ethical Review Authority, data protection oversight aligned with the European Data Protection Board and national law, and data use agreements managed by host institutions such as Karolinska Institutet and Uppsala University. Access procedures require approvals from institutional review boards and compliance with statutes referenced by authorities like the Ministry of Health and Social Affairs (Sweden). International collaboration follows models used by consortia including the International Genome Sample Resource and adheres to standards promoted by organizations such as the World Medical Association and the European Commission for cross‑border research. Data sharing has been facilitated in collaborative projects with repositories and networks including dbGaP, European Genome-phenome Archive, and multicenter initiatives led by Wellcome Trust–funded teams.

Category:Medical registries in Sweden