APP and Parkinson disease: PD neurons showed enrichment for “Mutation Caused Aberrant Abeta to Electron Transfer in Complex I” (p = 5.62E-11) and neuronal signaling pathways including “mGluR5 Ca2 + Apoptotic Pathway” and “VGCC Ca2 + Apoptotic Pathway,” which are specifically related to synaptic calcium signaling and neurotransmission.