Dopamine D2 receptor gene −141C Insertion/Deletion polymorphism in Turkish schizophrenic patients

Schizophrenia is a chronic and neuropsychiatric disease that affects about 0.5–1% of the world’s population. An increase in dopamine and dopamine D2 receptor (DRD2) gene products has been well described in schizophrenic patients. Several groups have studied the relationship between dopaminergic hyperactivity and cellular communications have obtained discordant results. Studies searching for the relationship between the schizophrenia and DRD2 gene have gained more interest. Our objective was to determine the relationships among schizophrenic symptoms in schizophrenia subtypes and severity of symptoms in terms of DRD2 gene −141C Insertion/Deletion [Ins/Del; I/D] polymorphism by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) assay method. Genomic DNA was prepared from peripheral blood by using salt extraction method. After amplification of genomic DNA, PCR products were digested with BstNI restriction enzyme for the detection of DRD2 gene −141C Ins/Del polymorphism in 73 schizophrenic patients and 60 healthy control subjects. The allelic frequencies of the DRD2 gene −141C Ins/Del polymorphism in case and control groups were 79.5 and 77.5% for I allele; 20.5 and 22.5% for D allele respectively. There was no significant difference in frequencies of genotypes and alleles between the two groups. In schizophrenic and control subjects, there were no significant relationship in severity of the disease and schizophrenia types among the −141C Ins/Del genotypes and alleles.