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.