Here we present results from a GWAS and subsequent replication based on analyses of the largest cohorts of diagnosed CUD reported so far. Individuals included in the discovery GWAS come from the Danish nation-wide population based cohort collected by the Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH). The iPSYCH cohort was ascertained to study six major psychiatric disorders (schizophrenia, bipolar disorder, major depressive disorder, attention-deficit hyperactivity disorder (ADHD), anorexia nervosa and autism spectrum disorder) and consists of 79,492 genotyped individuals. The present GWAS included 2,387 individuals with a diagnosis of CUD. In this study CUD was defined by individuals having an ICD10 diagnosis reflecting a problematic and persistent use of cannabis (ICD10 F12.1-12.9; see Supplementary Table 1, 2 and 3 for information on number of cases in each diagnostic subcategory and distribution over diagnostic subcategories in relation to comorbid psychiatric disorders) and 48,985 individuals not diagnosed with CUD, all from the iPSYCH cohort. We identify a genome-wide significant risk locus on chromosome 8, which replicates in an independt cohort from deCODE genetics. The index variant is a strong eQTL
