Colizzi and colleagues (2015) investigated the dopamine receptor D2 (DRD2) genotype rs1076560 locus and found that cannabis-using carriers of the T-allele had a three-fold increase in the odds of psychosis compared to GG carriers (OR = 3.07; 95% CI 1.22–7.63). This evidence concerns the gene DRD2 and psychotic disorder.