Mitochondrial diseases are a group of disorders caused by dysfunctional mitochondria, the organelles that generate energy for the cell. Mitochondria are found in every cell of the human body except red blood cells, and convert the energy of food molecules into the ATP that powers most cell functions. Reportedly, the first pathogenic mutation in mitochondrial DNA was identified in 1988. Between then and 2016, over 275 other disease-causing mutations were identified. Symptoms of mitochondrial diseases may include poor growth, loss of muscle coordination, muscle weakness, visual problems, hearing problems, learning disabilities, heart disease, liver disease, kidney disease, gastrointestinal disorders, respiratory disorders, neurological problems, autonomic dysfunction, autism-like symptoms, and dementia.