(CIT): The concept of heteroplasmy and threshold levels of mitochondrial mutations will be discussed. The Mitochondria Interest Group (MIG) is an Inter-Institute Interest Group at the National Institutes of Health (NIH), with members from NIH and from around the world! MIG is concerned with all aspects of the mitochondrion and diseases in which the mitochondrion is involved. For more information, visit the Mitochondria Interest Group (MIG).