Netherlands Twin Register (NTR, n=1051), the Queensland Institute of Medical Research (QIMR, n=3528), the Rotterdam studies (RS1, RS2 and RS3, n=5406), the Study of Addiction: Genetics and Environment (SAGE, n=1376), the SardiNIA study (n=2158), Twins UK I, II and III (n=3962) and the Women’s Genome Health Study (WGHS, n=22,028). Full details can be found in the Supplementary note. All studies were approved by local ethics committees and all participants provided written informed consent.
