Schizophrenia and the cannabinoid receptor type 1 (CB1): association study using a single-base polymorphism in coding exon 1.

Abuse of cannabis is frequent among the young and is suspected to precipitate schizophrenia in vulnerable subjects. Cannabinoid receptor (CB1) is particularly concentrated in dopamine-modulated areas of the nervous system. An association between an AAT polymorphism of the CB1 gene and intravenous drug abuse has been previously reported, but not with schizophrenia. In a French Caucasian population, we compared the distribution of a single-base polymorphism revealed by MspI within the first exon of the CB1 gene in patients with schizophrenia (n = 102) and ethnic- and gender-matched controls (n = 63). No significant difference was seen in the allele or genotype distribution between the whole sample of schizophrenic patients and controls. However, we found a borderline lack of allele g and a significant lack of gg genotype in the non-substance-abusing patients compared to substance-abusing patients, the latter being similar to the controls. These results are the first report of an significant association between CB1 receptor and a subtype of schizophrenia. Studies are needed to confirm and further explore the precise role of the cannabinoid system in schizophrenia. Copyright 2001 Wiley-Liss, Inc.