PLCG2 and Parkinson disease: The specific expression patterns of SORL1, primarily linked to memory in hippocampus and the CN in the AD brain (Tejada Moreno et al., 2022), along with elevated PLCG2 indicative of reactive microgliosis (Andreone et al., 2020) in the brain with AD as well as PD demonstrate the molecular complexity of these diseases in which previously reported AD risk genes and PD-associated markers failed to show statistical significances (Supplementary Figures S6–S11, S17).