The C957T gene polymorphism is a single nucleotide synonymous mutation located within the coding region of the DRD2 gene. Rather than being ‘silent’ the C allele influences mRNA stability and translation. As a result, the C allele alters dopamine-induced up-regulation of the D2 receptor.  Individuals with the CC genotype make a greater number of preservative errors on the Wisconsin Card Sorting Test  and exhibit a reward-related impulsivity endophenotype in response to acute psychosocial stress.  The CC genotype interacts with the COMT Val158Met polymorphism  and is associated with schizophrenia.  The CC genotype also interacts with the TaqI-A polymorphism of the ANKK1 gene and is associated with dissocial personality disorder.