No effective treatments are available for most neurodegenerative diseases. This study uses Ataxia-Telangiectasia (A-T), an early-onset inherited neurodegenerative disease of children, as a model to study the mechanisms leading to cerebellar neurodegeneration and to develop a drug that can slow or halt neurodegeneration. Aim1 proposed to use “Yamanaka factors” to reprogram A-T patient-derived skin fibroblasts, which carry nonsense mutations that we have shown can be induced by RTCs to express full-length and functional ATM protein, into iPSCs. We have successfully reprogrammed A-T fibroblasts to hiPSCs and teratoma formation shows their pluripotency. Aim2 will use these established iPSCs to model neurodegeneration, focusing on differentiation to cerebellar cells, such as Purkinje cells and granule cells. We have generated the Purkinje cell promoter –driven GFP reporter system and will use this system to examine the differentiation capacity of A-T iPSCs to Purkinje cells. Aim3 will utilize the newly-developed neural cells carrying disease-causing ATM nonsense mutations as targets for evaluating the potential therapeutic effects of leading RTCs. We have already started to test the efficacy and toxicity of our lead RTC compounds on A-T iPSC-derived neural progenitor cells. The continuation of this study will help us to pick up one promising RTC compound for IND application. This project is on the right track towards its objective for the development of disease models with hiPSCs and the test of our lead small molecule compounds for the treatment of A-T or other neurodegenerative diseases.