Linked polymorphisms (–333G>T and –286A>G) in the promoter region of the CCK-A receptor gene may be associated with schizophrenia

Cholecystokinin A receptors (CCKAR) modulate CCK-stimulated dopamine release, and mutations in the CCKAR gene may predispose affected individuals to schizophrenia. Our previous study suggested that -286A>G polymorphism (previously named 201A>G) in the CCKAR gene promoter is associated with schizophrenia. In the present study, we carried out a further investigation of the promoter and intron 1 of the CCKAR gene. In addition to polymorphisms reported previously (-333G>T, -286A>G, -241G>A, 773A>T, and 779T>C), two novel polymorphisms (-388(GT)(8)>(GT)(9) and -85C>G) were identified. These polymorphisms were in a linkage disequilibrium. Association analyses between schizophrenic patients and controls revealed that the frequencies of the A allele and AA genotype at the -286 loci, as well as the frequency of the GG genotype at the -333 loci, were significantly higher in patients than in controls. Furthermore, patients with paranoid type schizophrenia, auditory hallucinations, or a positive family history had a significantly higher frequency of the -286A allele than the control group. The results supported our previous data, and suggest the possible involvement of the -333G>T and the -286A>G polymorphisms in the promoter region of the CCKAR gene in the predisposition to schizophrenia.