Therefore, in this study, we sought to replicate the association with AD previously observed with ABI3 rs616338-T and PLCG2 rs72824905-G in Caucasians, test if this association is also observed in African-Americans, and determine if these variants associate with risk of other neurodegenerative diseases, namely Parkinson’s disease (PD), dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP) and multiple system atrophy (MSA). This evidence concerns the gene PLCG2 and Alzheimer disease.