Mitochondrial disease: when the powerhouse goes awry.

Knowledge of and interest in mitochondrial disease is relatively recent. The first diagnosis of a mitochondrial cytopathy occurred in 1962. Since then, researchers have elucidated hundreds of types of mutant mitochondrial DNA and mapped their repercussions. This article walks the reader through the basics of mitochondrial function--normal and mutant. Mitochondrial cytopathies appear first in organs with high-energy needs; once a threshold of mutant mitochondrial DNA is exceeded, manifestations can be single or multisystem conditions. Although these conditions are currently incurable, some therapies aimed at enhancing mitochondrial function or scavenging free radicals may help individual patients. Certain nonpharmacological therapies should be employed in all patients. Research findings suggest that mitochondrial functioning may have a greater role in other pathologies than previously assumed.