Role of genetic polymorphisms of the dopaminergic system in Parkinson's disease patients with impulse control disorders.

BACKGROUND: The mechanisms underlying the development of impulse control disorders (ICDs) like compulsive gambling, buying, sexual, and eating behaviors in Parkinson's disease (PD) are debated. We assessed whether allelic variants of dopamine D2 receptors (DRD2), catechol-O-methyltransferase (COMT) and dopamine transporter (DAT) were associated with the development of ICDs in PD.

METHOD: We enrolled 89 idiopathic PD patients (48 without ICDs and 41 with ICDs). All patients were screened with the Minnesota Impulsive Disorders Interview (MIDI) and fulfilled DSM-IV criteria for the ICD positive cohort. Differences in the frequency of the genotypes between ICDs and non-ICDs groups were assessed using the χ(2) test.

RESULTS: Genotyping was performed for variants of the DRD2 Taq1A (rs1800497), COMT Val(158)Met (rs4680), DAT1 (3' UTR 40bp VNTR). Variants of DRD2 Taq1A, COMT and DAT1 were not associated with the risk of developing ICDs.

CONCLUSION: In our study, there were no differences in the frequency of variant of DRD2 Taq1A, COMT and DAT1 between the two groups. Polymorphisms of dopaminergic genes do not play a relevant role in the development of ICD in PD suggesting that ICD originate from inability to filter inappropriate behaviors triggered by dopaminergic therapy.