In 801 patients with schizophrenia and 740 unaffected siblings, of 152 candidate single-nucleotide polymorphisms, the AKT1 rs2494732 polymorphism was the only one to emerge as interacting with cannabis.8 Carriers of two copies of the C allele of the rs2494732 (single-nucleotide polymorphism) of the AKT1 gene were at a twofold greater risk of being diagnosed with a psychotic disorder (patients) or having greater schizotypy (siblings) if they had used cannabis. This evidence concerns the gene AKT1 and psychotic disorder.