appendix p 18), although a different SNP was identified as the lead SNP (rs11783093). When rs11783093 was conditioned for the GWAS of smoking initiation, the signal was attenuated (p=1·55 × 10−6; appendix p 18). These findings suggest that the chromosome 8 signal might be partly driven by smoking initiation, or indicative of a pleiotropic effect with a stronger impact on cannabis use disorder than on smoking initiation.36 Despite the plausibility of CHRNA2 in the cause of cannabis use disorder, it is worth noting that EPHX2, which is involved in the metabolism of cannabinoids,56, 57, 58 was also identified in eQTL analyses but not supported by other post-hoc analyses (appendix p 29).
