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    The mtDNA Test Explained

    Tom Johnson
    Tom Johnson - 2020-07-28T21:00:00.000Z

    An mtDNA test can identify other people that are descended from the same female somewhere up the line. mtDNA can be unchanged over hundreds of years, so it can’t tell you whothe common ancestor  is – it could be somebody very distant or a much more recent relative.

    Everybody has mitochondrial DNA (mtDNA) inherited from their mother, which they inherited from their mother over generations. Sons and daughters both inherit mtDNA, but it’s only the daughters that then pass it on to their children.

    It’s possible that a person may share mtDNA with a descendent of direct-line females, but while males may also share mtDNA with another person, they are unable to pass it down to others.

    Test other mtDNA lines

    Though mtDNA is most commonly associated with tracing back maternal lines, you can also trace back using your father and his brothers and sisters to identify the mtDNA of their mother’s maternal line. This allows you to investigate other maternal lines genetically if you can find a relative who descends from a different line in your own ‘tree’.

    The relative you test doesn’t have to be female, but their mother should be directly descended through the relevant maternal line. It’s common for you to be able to test a father, paternal uncle, or child of a paternal uncle to help you discover the mtDNA of your paternal grandmother’s own maternal line.

    mtDNA levels

    If you are using mtDNA tests for genealogical purposes, these can only be conducted through Family Tree DNA, and it’s important if you do decide to go down this route that you do their Full Mitochondrial Sequence (FMS) test. If you did one of their earlier mtDNA tests that only checked a portion of your mtDNA, you can log into your account and order an upgrade to FMS.
     
    Some testing companies report mtDNA haplogroup predictions when providing autosomal DNA test results, but they are not comparable in terms of detail and reliability with an FMS test.

    The main reason for this is that they don’t test every SNP in the mitochondria, only the ones that are branch-defining, which means the produced data is not as strong.

    Furthermore, they do not compare your mtDNA with others to generate a list of maternal line matches.

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    mtDNA test - what is it good for?

    There is a range of practical applications for mtDNA testing, whether your interest is genealogical, biological or just inspired by curiosity.

    Some of the ways mtDNA tests can be used are:

    • Discovering the earliest possible origins of your maternal line by connecting with your mtDNA matches who have researched their own maternal line further back.
    • Helping fill in the gaps and finding connections between maternal lines where traditional record-keeping or physical data is inaccessible.
    • Discovering whether or not two women who share the same surname are related at some point down the line.
    • Determining if females who lives in different places, but who share an unusual surname, are related down the line.
    • Helping to solve maternity mysteries, including whether or not two siblings have the same mother or if cousins share the same maternal grandmother. You may also be able to discover which wife of a male ancestor who married more than once was the mother of a particular child or children. Additionally, it can help you discover if previously unknown cousin matches are related on the maternal or paternal side of the family, primarily by helping to eliminate particular relationships.

    mtDNA testing can also assist with broader genealogical research:

    • If you are unable to trace the surname of your most distant known maternal match then an FMS match can help provide clues for learning what it is.
    • If your autosomal DNA matches share the same mtDNA FMS haplogroup as any of your own tested mtDNA lines then you will be able to focus your research on the relevant direct maternal lines.

    mtDNA test

    Share your mtDNA test

    It is possible to share your test results with others, including members of your family. Your own haplogroup test result should be the same as your sister, brother, mother, mother’s sisters, and children of your mother’s sisters.

    It should also match with your maternal grandmother’s sisters’ daughters’, as well as a large number of more distant direct-line cousins who are of a maternal origin. In practical terms, this means you are able to complete one test and share the results with relevant family members, allowing you to break down the cost.

    It is particularly useful to share your results if you have matches with distant relatives or branches of your family that you may not have previously met. But if you do take this step then ensure you verify the match and aren’t jumping to incorrect conclusions.

    As we have already mentioned, mtDNA remains unchanged for many generations, stretching back hundreds of years, which means there are many people who’d be interested in learning of your results.

    There are instances of close relatives having slightly different mtDNA results, due to mutations in recent or current generations. If you believe that this could be the case for you, then conduct the test with one or more of your maternal female cousins to pinpoint where the mutation occurred.The mtDNA database is not as extensive as the broader autosomal DNA database, so you may not get precise or even warm matches straight away.  But, because an mtDNA test examines every SNP on the whole mitochondria, you won’t ever have to make an additional investment. And once you have completed your own test, you can wait for others to discover their own results and monitor any new matches that appear.