Book excerpt: Mitochondria produce the chemical energy necessary for eukaryotic cell functions; hence mitochondria are an essential component of health, playing roles in both disease and aging. More than 80 human diseases and syndromes are associated with mitochondrial dysfunction; this book focuses upon diseases linked to these ubiquitous organelles. Accumulation of mitochondrial DNA damage results in mitochondrial dysfunction through two main pathways. Mutation in mitochondrial DNA causes diseases such as Kearns-Sayre syndrome and Pearson syndrome. Mutation in chromosomal DNA causes diseases such as Parkinson's disease and schizophrenia. These and many other diseases are reviewed in this book. Key Features Presents the detailed structure of mitochondria, mitochondrial function, roles of oxidants and antioxidants in mitochondrial dysfunction. Includes summary of both causes and effects of these diseases. Discusses current and potential future therapies for mitochondrial dysfunction diseases Explores a wide variety of diseases caused by dysfunctional mitochondria.