The authors conducted a case-control study of Parkinson's disease patients with and without visual hallucinations to investigate associations of the polymorphisms of the dopamine receptors D2 32806 C>T (Taq1A), D3 Ser9Gly and Msp1, D5 978T>C and dopamine transporter 3'-UTR 40 bp VNTR with visual hallucinations in Parkinson's disease.
The frequency of the Msp I polymorphic allele, a variant of CYPIA1 (m2), was significantly higher in patients with PD (0.444) than in controls (0.349).