Because of the similarities in our observations between cases with pure PD and DLB, and because β-amyloid correlated with both α-synuclein and ATP13A2 protein levels (which correlated with each other), we suggest that ATP13A2 in pure Lewy body diseases is modulated mainly by the changes in α-synuclein rather than β-amyloid. This evidence concerns the gene ATP13A2 and Lewy body dementia.