Commentary: Human mitochondrial cytopathies.

Mitochondria provide energy (ATP) for all eukaryotic cells except mature erythrocytes and keratinocytes. They are abundant in cells that expend much energy, such as muscle, exocrine pancreas, nervous system, and heart cells, and motile sperm. Many mitochondrial enzymes are encoded by nuclear DNA and imported into the mitochondria. Like bacteria, mitochondria possess their own DNA and ribosomes. They are fueled by fatty acids and pyruvate, and through acetyl-coA enzyme can use fats, carbohydrates, and proteins as energy sources, producing ATP for cells. A high index of suspicion for mitochondrial mutations enables clinicians to recognize these unusual and rare disorders and provide proper genetic counseling. Mitochondrial cytopathies include a diverse group of diseases, affecting many organs, especially skeletal muscle and central nervous system, and are associated with abnormal mitochondria in skeletal muscle known as ragged red fibers. Mitochondrial DNA mutations are detectable in peripheral blood.