Homoplasmy is a term used in genetics to describe a mammalian cell whose copies of mtDNA are all identical. Homoplasmic mtDNA copies may be normal or mutated. Most mutations are heteroplasmic - only occurring in some copies of mtDNA - but it has been discovered that homoplastic mtDNA mutations may be found in human tumours.
The term may also refer to uniformity of plant plastid DNA, whether occurring naturally or otherwise.
^Ballana, E., Govea, N., de Cid, R., Garcia, C., Arribas, C., Rosell, J. and Estivill, X. (2008), Detection of unrecognized low-level mtDNA heteroplasmy may explain the variable phenotypic expressivity of apparently homoplasmic mtDNA mutations. Hum. Mutat., 29: 248–257. doi: 10.1002/humu.20639. Accessed October 21, 2012.
^Coller HA, Khrapko K, Bodyak ND, Nekhaeva E, Herrero-Jimenez P, Thilly WG. "High frequency of homoplasmic mitochondrial DNA mutations in human tumors can be explained without selection." Nature Genetics 28, 2001 Jun; pp. 147-50. DOI 10.1038/88859. Accessed October 21, 2012.