PROJECT SUMMARY Dilated cardiomyopathy (DCM) is a genetic cardiac disorder with high morbidity and an incidence of 1:250. Although generally thought of as a disease with monogenic heritability, recent genetic studies suggest complex polygenic causes. Functional profiles of polygenic cardiomyopathies are poorly understood and this hampers effective therapeutics development. Recent advances in stem cell technology such as patient- derived induced pluripotent stem cells (iPSCs) and genome-editing, provides an unprecedented opportunity to study such disease phenotypes. Cardiomyocytes will be differentiated from iPSCs taken from patients with two DCM related mutations and sequenced to understand transcriptome differences that may correlate with disease susceptibility. The analysis will be normalized by using CRISPR to create isogenic controls and also insert the mutations in healthy individuals that are related to these patients. We will then utilize the iPSC platform coupled with tissue engineering to develop engineered heart tissues composed of cardiac specific cells. We will perform single cell RNA sequencing to test the cell-cell interactions and crosstalk between the cells. We will also perform functional assays like calcium-handling and contractility. CRISPR/dCas9 systems will allow us to identify genes suitable for drug targeting. The overarching goal of the parent R01 grant is to understand underlying mechanisms of polygenic DCM using the iPSC platform. The proposed diversity supplement extends this work by studying patients of different ethnicities and considering how this factors in disease severity. African-American and Hispanic patients are underrepresented in health studies, and therefore more vulnerable to poor disease management. Dr. Carlos Vera will expand our cohort of 20 individuals by six iPSC lines derived from these minority populations and perform the proposed set of experiments.