Association study of the dihydropyrimidinase-related protein 2 gene and methamphetamine psychosis

Dihydropyrimidinase-related protein 2 (DRP-2 or DPYSL-2)mediates the intracellular response to collapsin, a repulsive extracellular guidance cue or axonal outgrowth. DRP-2 is also referred to as collapsin response mediator protein 2 (CRMP-2). We have previously demonstrated that the DRP-2 gene is associated with susceptibility to schizophrenia, but not to bipolar disorders. In addition, a genetic association was observed with paranoid-type schizophrenia, but not with hebephrenic-type schizophrenia. It has been well documented that repeated abuse of methamphetamine (METH) for a long period frequently produces psychotic symptoms, such as auditory hallucinations and delusions that are hardly distinguishable from those of paranoid-type schizophrenia. Therefore, we hypothesized that a certain genetic variant of the DRP-2 gene may affect individual vulnerability to the development of METH-induced psychosis. We examined the genetic association by a case-control method. The polymorphism *2236T>C in the 3' untranslated region of the DRP-2 gene, which has been shown to be a negative genetic risk factor for paranoid-type schizophrenia, was analyzed in 198 patients with METH psychosis and 221 corresponding healthy controls in a Japanese population. No significant association of the DRP-2 gene with METH psychosis was found. Neither did we find an association with the clinical phenotype of METH psychosis, such as the age of first consumption of METH, latency to development of psychosis after METH abuse, prognosis of psychosis after detoxification from METH use, complication of spontaneous relapse of psychosis without reconsumption of the drug, or multisubstance abuse status. These findings indicate that a genetic variant of the DRP-2 gene may not affect the risk of METH psychosis or any clinical phenotype of the disorder.