RAB12 and Alzheimer disease: Herein we describe that LRRK2-mediated phosphorylated Rab12 labels lysosomal structures, GVBs, in LRRK2 mutation carriers and idiopathic PD – and across clinically distinct neurodegenerative diseases (AD, DLB and primary tauopathies) not previously reported to be characterized by LRRK2 pathway dysfunction.