AKT1 and psychotic disorder: Certain variant (C/C genotype) of the AKT1 gene has been shown to give an increased likelihood of psychosis after life-time cannabis use (29), and looking at schizotypy proneness in unaffected siblings, Van Winkel and Genetic Risk and Outcome of Psychosis (GROUP) Investigators (52) found that genetic variation in AKT1 mediated both short-term as well as longer-term effects associated with use of cannabis.