GBA1 and Parkinson disease: An advantage of PD genetic studies in the Ashkenazi Jewish population (AJ) is the higher frequency of common founder mutations in the two PD-risk genes, Leucine-Rich Repeat Kinase 2 (LRRK2) and Glucosylceramidase β 1 (GBA1) (34% of AJ-PDs compared to up to 10% of PD patients in the general population), which allows the performance of targeted and specific analyses of the mutations’ dependent stratified manner [10].