NRGN and Alzheimer disease: The CSF level of CT-Ng significantly correlated with of all synaptic markers FL-Ng (rho = 0.595, P = 0.003), SNAP-25 (rho = 0.636, P = 0.001), synaptotagmin, 215–223 (rho = 0.677, P = 0.0004), and synaptotagmin, 238–245 (rho = 0.702, P = 0.0002) [6, 7] in AD patients.