Heteroplasmy

Heteroplasmy is the presence of more than one type of organellar genome (mitochondrial DNA or plastid DNA) within a cell or individual. It is an important factor in considering the severity of mitochondrial diseases. Because most eukaryotic cells contain many hundreds of mitochondria with hundreds of copies of mitochondrial DNA, it is common for mutations to affect only some mitochondria, leaving most unaffected.

Although detrimental scenarios are well-studied, heteroplasmy can also be beneficial. For example, centenarians show a higher than average degree of heteroplasmy.[1]

At birth, all copies of mitochondrial DNA are thought to be identical in most humans.[2] Microheteroplasmy is mutations of up to about 2−5% of mitochondrial genomes, and is present in most adults. This refers to hundreds of independent mutations in one organism, with each mutation found in about 1–2% of all mitochondrial genomes.[3] Very low-level heteroplasmic variance is present in essentially all individuals, even those who are healthy, and is likely to be due to both inherited and somatic single base substitutions.[2]

  1. ^ Rose G, Passarino G, Scornaienchi V, Romeo G, Dato S, Bellizzi D, Mari V, Feraco E, Maletta R, Bruni A, Franceschi C, De Benedictis G (2007). "The mitochondrial DNA control region shows genetically correlated levels of heteroplasmy in leukocytes of centenarians and their offspring". BMC Genomics. 8: 293. doi:10.1186/1471-2164-8-293. PMC 2014781. PMID 17727699.
  2. ^ a b Payne BA, Wilson IJ, Yu-Wai-Man P, Coxhead J, Deehan D, Horvath R; et al. (2013). "Universal heteroplasmy of human mitochondrial DNA". Hum Mol Genet. 22 (2): 384–90. doi:10.1093/hmg/dds435. PMC 3526165. PMID 23077218.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ Smigrodzki, R. M.; Khan, S. M. (2005). "Mitochondrial Microheteroplasmy and a Theory of Aging and Age-Related Disease". Rejuvenation Research. 8 (3): 172–198. doi:10.1089/rej.2005.8.172. PMID 16144471.