PROJECT SUMMARY/ABSTRACT This is a research grant application for a study being undertaken in the laboratory of Dr. Aras Mattis, a Scientist at the University of California, San Francisco (UCSF). This grant will provide support for the Mattis lab to conduct this research over the five-year term of this project. Differentiation of patient induced pluripotent stem cells (iPSCs) to hepatocytes (iPSC-Heps) has incredible value for modeling and experimental treatment of human hepatic disease. My lab has significant expertise in the differentiation of iPSCs to human hepatocytes and therefore modeling of liver diseases. The major goal of this project is to use iPSC-Hep cell lines that we have developed from a single family of patients with NASH and matched controls to study modeling of NAFLD in vitro and the relationship of novel genes we uncovered to the disease process. First, we will use the iPSC-Hep model to test a set of genes with unknown function for involvement in NAFLD. We uncovered these genes by sequencing this family with severe and penetrant NASH. Furthermore, we will test loss of function knockouts of these novel genes in control iPSC- Heps, for their ability to cause steatosis, endoplasmic reticulum (ER) stress, and/or inflammatory pathway activation. Finally we will test a set of genes we uncovered as potentially therapeutic targets. The specific experimental aims of this project are to 1) Identify NAFLD pathways modeled in patient 7017 familial NASH iPSC-Heps, 2) Establish contribution of known SNPs and novel genes for involvement in NAFLD Phenotypes, and 3) Test our previously identified genes as therapeutic targets in 7017 iPSC-Heps. This project follows the mission of the NIH to support medical research on hepatic diseases with the potential for clinical translational use.