Cannabis use is increasing in the population1 and around 9% of users become dependent2. Genetic factors explain a large proportion of the risk for cannabis use disorder (CUD) with twin heritability estimates in the range of 513-70%4. The prevalence of diagnosed CUD in the population has been estimated to 1-1.5% among Europeans5 and Americans1. CUD is associated with a range of adverse health problems6 including risk of psychosis7, bipolar disorder8, anxiety disorder9 and cognitive impairment with more persistent use associated with greater decline10. Estimates of the heritability for cannabis use initiation and life-time cannabis use, with respect to the amount of variance explained by common variants (i.e. the single nucleotide polymorphism (SNP) heritability), has been estimated to 0.0611-0.212. Four GWASs related to cannabis use initiation or lifetime use have been conducted; three studies without genome-wide significant findings11-13 and a large GWAS meta-analysis of life-time cannabis use including 184,765 individuals, wich identified eight genome-wide significant independent risk loci14. Four GWASs of problematic use or diagnosed CUD have been conducted; two without genome-wide significant findings15,16 and two recent reporting genome-wide significant associations,
