NRGN and Alzheimer disease: Based on such evidence, in line with previous observations [22], we speculate that Ng may act as a "topographic" marker of cortical and hippocampal pathology, not only in AD [37] but also CJD, as demonstrated by the high CSF levels observed in sCJD subtypes with prominent cortical pathology (MM(V)1, MM(V)2C and VV1) and the unexpectedly low concentrations reported in VV2 (in whom subcortical and cerebellar pathology is prevailing) [3].