Association between obsessive disorder and polymorphisms of dopamine receptor genes

Abstract

Objective To explore the association between obsessive-compulsive disorder and polymorphisms of dopamine(DA) receptor genes: the dopamine D2 receptor( DRD2 ) 141C Ins/Del,and the dopamine D3 receptor( DRD3 ) 25A/G(9Ser/Gly) polymorphism in the northern Han nationality. Methods 164 OCD patients and 175 healthy controls were included in this study. The genotypes of DRD2 and DRD3 were determined with polymerase chain reaction amplification fragment length polymorphism techniques(PCR-RELP). Results Generally speaking, OCD patients did not show significant differences in genotype distribution and allele frequency for polymorphisms investigated relative to controls. However, when the sample was stratified by gender, age at onset,with or without comorbidity, and OCD symptom dimensions, there was a trend to a significant predominance of the DRD3 Gly/Gly genotype,and a higher frequency of the DRD3 Gly allele in female OCD patients compared to female controls. In addition,an association of the DRD2 Ins/Ins genotype or DRD2 Ins allele in patients with an early onset OCD was observed. Either DRD2 or DRD3 was significantly different between controls and subtype of OCD with comorbidities or OCD with obsession and compulsion in the genotype distribution and allele frequency. Conclusion The results provided support for a potential role of the DRD2 and DRD3 locus in subgroup of female, early onset patients, OCD with comorbidities, and OCD with obsession and compulsion. Further studies will need to investigate the differences between OCD genetics and clinical variables such as gender, age at onset and comorbidity of the disorder to improve the identification of OCD subtypes and genetic etiology. Key words: Obsessive-compulsive disorder; Gene; Polymorphism; Reaction fragment length; Dopamine D2 receptor; Dopamine D3 receptor