The concept of mitochondrial diseases originated in 1962 with the description by Luft and coworkers of a patient with nonthyroidal hypermetabolism due to loose coupling of oxidation and phosphorylation in muscle mitochondria. Over the following quarter of a century, thanks to W. King Engel's "ragged-red fibres" as convenient markers for mitochondrial pathology, numerous papers described clinical, morphological, and biochemical features of "mitochondrial myopathies." In 1988 the discovery of mutations in mitochondrial DNA led to an explosive expansion of research into mitochondrial disorders. Throughout the 1990s the rapid identification of multiple mitochondrial gene defects associated with clinically diverse disorders has left practitioners puzzled about diagnosing such heterogeneous and complex syndromes. Through updated data, this book discusses now what Luft aptly called "mitochondrial medicine." In so doing, it considers the pivotal role of mitochondria in drug sensitivity, their key roles in ageing, apoptosis, and neurodegeneration along with primary mitochondrial diseases due to mutations in the nuclear genome, in the mitochondrial genome, or in the cross-talk between the two genomes.