Mitochondria– an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It has a double membrane, the inner part being folded inwards to form layers (cristae). Mitochondrial diseases result from failures of the mitochondria, specialized compartments present in every cell of the body except red blood cells. Mitochondria are responsible for creating more than 90% of the energy needed by the body to sustain life and support growth. When they fail, less and less energy is generated within the cell. Cell injury and even cell death follow. If this process is reiterated all over the body, whole systems begin to fail, and the life of the person in whom this is happening is severely compromised. The disease primarily affects children, but adult onset is becoming more and more common. Diseases of the mitochondria appear to cause the most damage to cells of the brain, heart, liver, skeletal muscles, kidney and the endocrine and respiratory systems. Depending on which cells are affected, symptoms may include loss of motor control, muscle weakness and pain, gastro-intestinal disorders and swallowing difficulties, poor growth, cardiac disease, liver disease, diabetes, respiratory complications, seizures, visual/hearing problems, lactic acidosis, developmental delays and susceptibility to infection. Mitochondrial diseases can be treated by a noval method of “GENE EDITING”. A new genetic engineering technique could help prevent mitochondrial diseases without the ethically sticky “three-parent problem” of another recently developed method. The three-parent technique involves transferring the nucleus of a prospective mother’s egg into a donor egg containing healthy mitochondria in order to replace mutant mitochondria with healthy ones. The new gene-editing method removes or depletes the number of mutant mitochondria from eggs or early embryos. This methodology could preserve mitochondrial diseases from being passed from mother to child.