The Norwegian Twin Registry

  • Thomas S. Nilsen
  • Ingunn Brandt
  • Nikolai Czajkowski
  • Gun Peggy Knudsen
  • Per Magnus
  • Ted Reichborn-Kjennerud
  • Kristian Tambs
  • Jennifer R. Harris
  • Ragnhild Ørstavik


The Norwegian Twin Registry (NTR) is a large population based twin cohort for research purposes. At present,
the registry has 14 692 complete twin pairs with information on zygosity and to varying degree information on
somatic and mental health, lifestyle and demographics. The registry covers birth years 1895-1960 and 1967-
1991. NTR was established in 2009, at the Norwegian Institute of Public Health, as a merger of three major
twin panels, the oldest originating in the 1960s. Since then Norwegian twin research has been a notable
contributor to twin research internationally. Norwegian twin researchers have published over 250 papers based
on Norwegian twin data, spanning a broad range of somatic and mental health phenotypes. In twin studies of
heritability a data structure with both variance within and between pairs is required. Therefore a large sample is
necessary, especially when studying rare diseases and conditions, and it is of vital importance to expand the
registry. NTR is actively recruiting new twins, both young and older, but declining response rates are a
challenge. The value of NTR is greatly enhanced through the linkage possibilities offered by Norway’s many
nationwide registries (medical, demographic, and socio-economic). Access to data is permitted by the NTR
steering group and will in most instances need permission from the Regional Ethics Committee.


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How to Cite
Nilsen, T. S., Brandt, I., Czajkowski, N., Knudsen, G. P., Magnus, P., Reichborn-Kjennerud, T., Tambs, K., Harris, J. R., & Ørstavik, R. (2016). The Norwegian Twin Registry. Norsk Epidemiologi, 26(1-2).