Ca-HL was defined using similar questions in the Semi-Structured Assessment for Drug Dependence and Alcoholism (SSADDA)13 (for Yale-Penn) and the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA)14 (for COGA). For the SSADDA, this question is, “Has your use of [marijuana] ever caused you emotional or psychological problems like: Hearing, seeing, or smelling things that weren’t really there?” In the SSAGA, the question is “Because of your marijuana use, did you ever experience any of the following: Hearing, seeing or smelling things that weren’t really there?”. As in Yale-Penn samples >90% of participants with Ca-HL used cannabis ≥1 year and ≥100 times, these two criteria were used to define comparison subjects (controls) who were long-term cannabis users without Ca-HL. The same criteria were used to select samples from COGA. The sample sizes of our GWAS were not predesigned for ensuring adequate power to detect a pre-specific effect size.
