Genetic Modifiers of Alzheimer Risk Administrative Supplement We have identified a blood biomarker signal that differentiates genetically mutant Alzheimer disease (AD)-model mice from their age- and sex-matched non-mutant littermates: markers of the cellular response to DNA damage. This supplement to the KOMP project will define the detection limits of the assay signal in time, pre-disease, and breadth of models detectable, and will examine viable knock-out mice generated in the KOMP project for signal in the blood assay as a simple screen for knock-outs with AD and pre-AD properties. This work has the potential to identify new AD risk alleles, and to produce a simple, early initial blood-based biomarker and assay for AD risk. Simple blood screens for pre-AD phenotypes could allow identification and potentially prevention of symptoms in at-risk individuals not otherwise identified.