In the first phase, expression profiles of pure populations of microglia from physiological aging, accelerated aging (Ercc1), disease mouse models for AD (App-Ps1) and ALS (Sod1) mice, and acute immune activated (i.p. injection with LPS) microglia were obtained and preprocessed in parallel (Figure 1, phase 1). The gene discussed is ERCC1; the disease is Alzheimer disease.