Each cell contains hundreds of mitochondria. They play important role in energy production.

Central nervous system, heart, skeletal muscles, kidneys, endocrine glands have the highest application for energy and thus are most stricken with mitochondria diseases. Mitochondria diseases are transmitted only by mother (sperm does not contain mitochondria), phenotypical effects are various depending on the proportion of mutated and not mutated mitochondria. There are rare diseases.