The allele frequencies of DRD2 C957T were not significantly different between the CWS and the CWNS; however, the frequency of the TT genotype was significantly higher among the CWS (p = 0.02), which was associated with 2.25-fold susceptibility to stuttering (OR = 2.25, 95% CI = 1.03 to 4.90, p = 0.04).
This idea is supported by an additional path model showing that the polymorphism DRD2 C957T influences the self-reported severity of stuttering mainly by its influence on neuroticism (independent of the variable sex).