Visual hallucinations are significant nonmotor symptoms in the course of treatment of Parkinson's disease. Previous studies have shown that the interindividual variability and pharmacogenetic profile of Parkinson's disease patients seem to influence the occurrence of visual hallucinations. In our study, we investigated a possible relationship of sequence variants in DRD1, DRD2, DRD3, DAT1, and COMT genes with the presence of visual hallucinations in Parkinson's disease patients. A total of 224 Brazilian patients from the Pro-Parkinson service at the Clinical Hospital of the University of Pernambuco, diagnosed with sporadic Parkinson's disease, were enrolled. Parkinson's disease patients were divided into 2 groups based on the presence or absence of visual hallucinations. The sequence variants for DRD1, DRD2, DRD3, DAT1, and COMT were determined through the polymerase chain reaction-restriction fragment length polymorphism technique. Multiple Poisson regression analyses showed that individuals carrying the DRD3 Ser/Ser and Ser/Gly genotypes presented increased prevalence ratios of visual hallucinations (9.7-fold and 4.4-fold, respectively; P < .001). Regarding DAT1 rs28363170, there was a 9.82-fold increase in the prevalence ratio in patients with the 10/11 genotype, 8.78-fold for the 10/8 genotype, and 2.44-fold for the 9/8 genotypes (P < .001, for all). In addition, visual hallucinations were also associated with use of transdermal patches with rotigotine (PR, 3.7; 95%CI, 1.2-10.9; P = .017) and rasagiline (PR, 2.8; 95%CI, 1.3-6.0; P = .006). Our results suggest that the genetic variants DRD3 and DAT1, along with other therapeutic confounders, may influence the prevalence ratio of visual hallucinations.

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