The Norwegian twin registry

Abstract

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.