NRGN and Alzheimer disease: Second, in an effort to estimate the proportion of C‐terminal Ng fragments to total‐Ng content, we depleted full‐length Ng and mainly N‐terminal Ng fragments from several individual AD and control CSF samples and measured by sandwich ELISA the concentration of the remaining Ng which represented mainly the C‐terminal Ng fragments, allowing estimation of the proportion of C‐terminal fragments to total‐Ng content.