Autopsy studies have found tau to colocalize with alpha-synuclein in Lewy bodies in both Parkinson’s disease and dementia with Lewy bodies.56 A small autopsy study in LRRK2 carriers found that 100% of the brains had tau pathology.57 Therefore, it is possible that the Lewy body disease risk genes associated with tau pathology are not good candidates to distinguish LBD-D from LBD-ND. The gene discussed is SNCA; the disease is Parkinson disease.