Lack of association between obsessive-compulsive disorder and the dopamine D₃ receptor gene: Some preliminary considerations

Controversial results possibly suggesting an association between Tourette's Syndrome (TS) and excess of homozygosity at a Msc I polymorphism in the Dopamine D₃ receptor (DRD₃) gene have recently been reported. Since a relationship between Obsessive-Compulsive Disorder (OCD) and Tourette's Syndrome (TS) has been suggested, in this study we assessed the frequency of this 2-allele polymorphism in a sample of 97 OCD patients and in 97 control subjects. No statistically significant differences in allele or genotype frequencies were found. Thus this mutation in the coding sequence of the DRD₃ gene is unlikely to confer susceptibility to OCD.