Mitochondria generate most of the energy required for cellular function by oxidizing fatty acids and sugars. Disruption of this process can result in fatal mitochondrial disease, affecting heart, brain and liver function. We will transform skin cells from patients with mitochondrial fatty acid oxidation disorders into induced pluripotent stem cells, and then differentiate these stem cells into cardiomyocytes and neurons. This will allow us to examine mitochondrial energy generation in specific human cell types and define the function of proteins involved in mitochondrial fatty acid oxidation and oxidative phosphorylation. This will provide novel insights into both mitochondrial metabolism and disease pathophysiology.