Mitochondrial disorders are a group of diseases caused by dysfunction in the mitochondria, which are the energy-producing structures within cells. These disorders can affect various organs and systems in the body, leading to symptoms such as muscle weakness, neurological issues, and problems with growth and development. The severity and type of symptoms can vary widely among individuals, depending on which cells are affected and the extent of the dysfunction. Mitochondrial disorders can be inherited from parents or occur spontaneously due to mutations in mitochondrial DNA or nuclear DNA that affect mitochondrial function.