MedGen

Progressive damage to mitochondrial DNA (mtDNA) during life is thought to contribute to aging processes. This notion is supported by the observation of an aging-related accumulation in human mtDNA of oxidative and alkylation derivatives of nucleotides, of small deletions and insertions, and of large deletions, although their low frequency raises questions about their functional significance (Michikawa et al., 1999). [from OMIM]

A mode of inheritance that is observed for traits related to a gene encoded on the mitochondrial genome. Because the mitochondrial genome is essentially always maternally inherited, a mitochondrial condition can only be transmitted by females, although the condition can affect both sexes. The proportion of mutant mitochondria can vary (heteroplasmy). [from HPO]