The detection of genetic mutations such as PINK, GBA1, and LRRK2 that are associated with increased risk for developing PD paved the way for a paradigm shift in PD diagnosis and the prodromal phase prior to the appearance of clinical symptoms [34,92]; providing a window period for establishing early markers with predictive validity for PD [82,92]. This evidence concerns the gene LRRK2 and Parkinson disease.