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mtDNA Mutations Frequently Asked Questions

What are mtDNA mutations?

Mutations are changes to your DNA code. They are natural copying errors. One analogy is to think of a copy machine that is making many copies of a page. Occasionally the printer will make a mistake, for example, an “e” might look more like an “o.” This is a “mutation.” If you then take that page with the “o” and copy it, it will pass on its “mutation” to all of its descendant copies.

How do mitochondrial mutations occur?

Every human cell contains hundreds of mitochondria. Each mitochondrion in a cell contains multiple copies of its own DNA (mtDNA). A new mitochondrial mutation occurs in only one copy of the mtDNA in one mitochondrion in one cell. Depending on the location of that cell, the new mutation may become more common in the individual over their lifetime. If it occurs in a woman’s egg cell, future generations have the potential to pass it on.

Are some mtDNA mutations more common than others?

We see some mitochondrial DNA mutations more often than others. One mutation which we find often in a number of different haplogroups is C16311T in the HVR1 result. This is a base pair in the mitochondrial DNA that seems to have mutated many different times in human history.

Is my mtDNA mutation medical?

FamilyTreeDNA offers mtDNA full sequence tests strictly for genealogy and personal ancestry information purposes. We do not examine or discuss the medical implications of any person’s mtDNA. 

What is the Reconstructed Sapiens Reference Sequence (RSRS)?

The Reconstructed Sapiens Reference Sequence (RSRS) is a mitochondrial DNA (mtDNA) reference sequence that uses both a global sampling of modern human samples and samples from ancient hominids. It was introduced in early 2012 as a replacement for the rCRS (revised Cambridge Reference Sequence). Because it is based on the likely modal haplotype of the common ancestor to both modern humans and such ancient groups as the Neanderthals, it shows an unbiased path back from any one modern mtDNA sequence to our distant common maternal ancestor.

Source: Behar, D. M., van Oven, M., Rosset, S., Metspalu, M., Loogväli, E.-L., Silva, N. M., Kivisild, T., Torroni, A., and Villems, R. (2012). A ”Copernican” reassessment of the human mitochondrial DNA tree from its root. The American Journal of Human Genetics, 90(4):675-684.

What is the revised Cambridge Reference Sequence (rCRS)?

The revised Cambridge Reference Sequence (rCRS) is the revised sequence based on the first mtDNA sequence completed (Cambridge Reference Sequence). The Cambridge Reference Sequence (CRS) is the mitochondrial DNA sequence first sequenced in 1981. It was used as a basis for comparison with mtDNA test results until it was replaced with the RSRS.

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