Association between obsessive-compulsive disorder and a variable number of tandem repeats polymorphism in intron 2 of the serotonin transporter gene.

BACKGROUND Pharmacological studies indicate a dysregulation of the serotonergic system in obsessive-compulsive disorder (OCD). A variable number tandem repeats (VNTR) polymorphism with three alleles (Stin2.9, Stin2.10, Stin2.12) has been described in intron 2 of the serotonin transporter (5-HTT) gene. This polymorphism has been associated with unipolar depression, bipolar disorder, schizophrenia, and anxiety disorders including OCD. METHODS The association between OCD and the polymorphism is examined in 97 OCD patients, 578 psychiatric controls and 406 healthy controls, all Spanish Caucasians. RESULTS Genotype frequencies for the polymorphism were significantly different in OCD patients, psychiatric patients and controls. There was a significant excess of 12/12 and 12/10 genotypes in OCD patients compared to psychiatric patients and controls. CONCLUSIONS Our results indicate a possible association between the Stin2.12 allele of the VNTR polymorphism and OCD.