We combined stage 1 and stage 2 data using both the OR-based and the weighted z score-based meta-analysis approaches described above (Stage 1 meta-analysis). We also assessed our results using random effects meta-analysis to better account for any heterogeneity between the studies (Supplementary Table 6). Locus-specific and combined sibling relative risk estimates were calculated using sample size-weighted estimates of the effect size and risk-allele frequency derived from stage 2 replication samples only, and under the assumption of allelic and locus independence, as described by26,27.
