Objective: The dopamine D4 receptor (DRD4) is a candidate gene for increasing genetic susceptibility to schizophrenia. A recent study found that a -521C>T promoter base pair change affects transcriptional regulation of the DRD4 gene. The present study was designed to investigate the role of both the -521C>T single nucleotide polymorphism and the DRD4 variable number tandem repeat (VNTR) polymorphism.
Methods: A case-control study of 630 Chinese schizophrenic patients and 428 Chinese controls was conducted to test for allelic association with schizophrenia.
Results: The number of DRD4 VNTR fragments was associated with schizophrenia. Long DRD4 VNTR fragments as opposed to short fragments were commoner in schizophrenia. No evidence was found for allelic association between the -521C>T DRD4 polymorphism and schizophrenia.
Conclusions: This study provides preliminary and unconfirmed evidence for the involvement of the DRD4 repeat VNTR in the pathogenesis of schizophrenia.