Polymorphisms of Dopamine Receptor Genes and Risk of L-Dopa-Induced Dyskinesia in Parkinson's Disease.

L-dopa-induced dyskinesia (LID) is a frequent motor complication of Parkinson's disease (PD), associated with a negative prognosis. Previous studies showed an association between dopamine receptor (DR) gene ( DR ) variants and LID, the results of which have not been confirmed. The present study is aimed to determine whether genetic differences of DR are associated with LID in a small but well-characterized cohort of PD patients. To this end we enrolled 100 PD subjects, 50 with and 50 without LID, matched for age, gender, disease duration and dopaminergic medication in a case-control study. We conducted polymerase chain reaction for single nucleotide polymorphisms (SNP) in both D1-like ( DRD1 A48G; DRD1 C62T and DRD5 T798C) and D2-like DR ( DRD2 G2137A, DRD2 C957T, DRD3 G25A, DRD3 G712C, DRD4 C616G and DRD4 nR VNTR 48bp) analyzed genomic DNA. Our results showed that PD patients carrying allele A at DRD3 G3127A had an increased risk of LID (OR 4.9; 95% CI 1.7-13.9; p = 0.004). The present findings may provide valuable information for personalizing pharmacological therapy in PD patients.