APOE and Alzheimer disease: Among the genetic contributors, the Apolipoprotein E (APOE) gene, specifically the \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\varepsilon4$$\end{document} allele, is the most well-established risk factor for AD, associated with both increased susceptibility and earlier disease onset [9].