We estimated the power of our GWAS meta-analysis sample to detect signals at the p<5E-08 significance threshold assuming an LD (r2) of 0.8 between the causal allele and the marker allele, as previously suggested [40]. To account for intraclass correlation within 78 DZ pairs included in the FinnTwin sample, we estimated the effective sample size (Neff) for these 156 DZ twins using the formula Neff = N/(1 + (m ‐ 1)ICC), where N is the number of DZ twins (156 twins in our case), m is the number of observations in a group (2 in our case), and ICC is the intraclass correlation (0.26 estimated from FinnTwin data), resulting in an estimated effective sample size of 124 (a reduction of 32). Thus, the effective sample size in our meta-analysis was reduced from 1518 to 1486. We performed power analyses using the Genetic Power Calculator [41].
