We propose to establish a comprehensive, validated repository of adult human dermal fibroblasts and human induced pluripotent stem cell (hiPSC) lines from frontotemporal dementia (FTD) patients with genetically defined mutations and familial, non-mutation carrying controls. hiPSCs hold tremendous promise for the development of in vitro FTD models for studying disease pathogenesis in relevant human cell types that would otherwise be impossible to obtain, such as human neurons. Using an established, collaborative, multi- institutional approach, we will bank adult human dermal fibroblasts from FTD patients carrying common mutations in the genes currently known to cause FTD: tau (MAPT), C9ORF72, and progranulin (GRN). In Aim 1, we will recruit both FTD patients with defined genetic mutations and control subjects. Comprehensive and longitudinal clinical evaluations will be linked to each cell line, allowing us to correlate disease characteristics with molecular phenotypes. In Aim 2, we will reprogram fibroblasts into hiPSCs by non-DNA-integrating technologies with which we have had recent success. In addition, we will further create EGFP reporter lines for monitoring and standardizing differentiation protocols in FTD-relevant cell types such as forebrain neurons. We will also correct selective mutations to create isogenic control lines so that we can precisely differentiate mutation-specific phenotypes from the noise of inter-individual variability. In Aim 3, we will derive and validate human neurons to model and study FTD pathogenesis in culture and to deliver hiPSC lines with robust phenotypes for FTD research and drug development. Based on our previous research experience in RNA and Tau biology and pathophysiology, we will focus on human neurons with GGGGCC repeat expansions in C9ORF72 and MAPT mutations. All cell lines will be banked at the Coriell Institute and will be accessible to the worldwide FTD research and drug development community. These resources should significantly alter the FTD research landscape by accelerating discovery.