This means that only patients which have a predisposition for PD due to mutations in one of the genes like LRRK2, SNCA etc. are prone to develop PD when the CYP2D6 gene is mutated, whereas none of the SNPs alone (OR values in IPD patients of 0.228 and 0.229 were found) seems to be sufficient to cause symptoms of PD. This evidence concerns the gene CYP2D6 and Parkinson disease.