NRGN and Alzheimer disease: Often only the cleaved fragment might serve as a biomarker; examples include the AD biomarkers amyloid-\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\beta$$\end{document}β and neurogranin [103, 119].