This presentation will focus on the diseases that disrupt the normal process of copying our mitochondrial DNA. Dr. Copeland will summarize the genes (POLG, POLG2, TWNK, and SSBP1) that are involved in copying our mitochondrial DNA and how they participate in preventing or causing mutations in mitochondrial DNA. Then he will focus on the diseases caused by mutations in these genes and the consequences of these mutations on mitochondrial function and health.