NRGN and Alzheimer disease: Synaptic-related proteins neurogranin, synaptotagmin, synaptotagmin-1, synaptophysin, synaptopodin, GAP43, SNAP25, NMDAR2A, L1CAM, AMPA4, NPTX2, NLGN1, and NRXN2α exhibited significant decreases in patients with AD.