14,15 However, cross-sectional analyses of patients with established PD with both LRRK2 and GBA variations suggest that carriers of LRRK2/GBA may instead have a less severe clinical course than those harboring GBA variations only,15,16 including less severe motor symptoms, and less dementia, and less severe nonmotor features in LRRK2/GBA PD compared with GBA PD.15,16 Because there are founder variations for LRRK2 G2019S and GBA variations in individuals of Ashkenazi Jewish descent, the likelihood of identifying carriers of LRRK2/GBA is increased in this ethnic group. Here, LRRK2 is linked to Parkinson disease.