In the no cost extension period for this new cell line award we completed the basic analysis of ten human embryonic stem cell (hESC) lines generated at UCLA and performed a comprehensive analysis of five additional hESC lines with trisomy 21 which constitute a unique disease model for Down Syndrome. Our data on the five Down Syndrome hESC lines reveals unique abnormalities in neural progenitor cell differentiation. Taken together, this New Cell Line Award has resulted in the generation of unique hESC tools for the scientific community, and in particular we demonstrate that hESC lines with Trisomy 21 have the potential to contribute unique perspectives on the underlying mechanisms of disease in individuals with Down Syndrome.