CTSD and Alzheimer disease: The G2 (up-down) also includes proteins located on multiple known AD-risk loci such as SPI1 and Protein Tyrosine Kinase 2 Beta (PTK2B), as well as other proteins known to be implicated on AD or neurodegeneration such as Brain-Derived Neurotrophic Factor (BDNF)37,38, Cathepsin D (CTSD)39,40, and Nuclear Factor Kappa B Subunit 1 (NFKB1) 41,42.