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Understanding 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 mtDNA 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 mutations common? 

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. 



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