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X-Match of 40.6 Centimorgans (cM) between my uncle and 1st cousin

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  • X-Match of 40.6 Centimorgans (cM) between my uncle and 1st cousin

    My uncle Norman Hagan took the mtDNA test as well as my 1st cousin Joan. I got a match of 40.6 Centimorgans (cM) on chromosome 23. I understand that the female has XX and the male one X. What does this mean when I am comparing between my uncle and his niece?
    Rich

  • #2
    Originally posted by richjh View Post
    My uncle Norman Hagan took the mtDNA test as well as my 1st cousin Joan. I got a match of 40.6 Centimorgans (cM) on chromosome 23. I understand that the female has XX and the male one X. What does this mean when I am comparing between my uncle and his niece?
    Rich
    Maybe I'm misunderstanding what you've written. You mention the mtDNA test and then mention a match on chromosome 23.

    The mtDNA test doesn't involve any of the chromosomes, which are inside the nucleus. The mtDNA test is done on mitochondrial DNA, which is outside the nucleus.

    You also wrote that your uncle and cousin took the mtDNA test. Then you wrote, "I got a match of 40.6 Centimorgans (cM) on chromosome 23." It seems that you, not your uncle or cousin have the match on the x chromosome. Who is this x chromosome match between among your uncle, your cousin and you?

    You'll need to clarify these points before we can answer your question.

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    • #3
      Please forgive me I meant to say GEDMatch X one-to-one. I was a little tired from jumping to GEDMatch, FamilyFinder, mtDNA and yDNA.
      Rich

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      • #4
        The X match is from my uncle Norman Hagan and his niece Joan Bailie. Along with FamilyFinder they both also tested mtDNA.
        Rich

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        • #5
          This shows my X match,
          Rich

          [IMG]/Users/richjh101/Desktop/X-chromosome.png[/IMG]

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          • #6
            and why do I have such trouble getting my images to show.
            Rich

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            • #7
              I keep forgetting to say the X-match is from GEDMatch
              Rich

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              • #8
                Originally posted by richjh View Post
                The X match is from my uncle Norman Hagan and his niece Joan Bailie. Along with FamilyFinder they both also tested mtDNA.
                Rich
                In your initial post, you asked, "What does this mean when I am comparing between my uncle and his niece?"

                How is your uncle related to his niece? Is his brother or sister the parent of the niece? It makes some difference in accounting for the inheritance of the x segment they share.

                If the niece is related to your uncle because her father is his brother, then the x segment they share is coming from her paternal grandmother, the mother of her father and your brother. If the niece is related to your uncle because her mother is the uncle's sister, then the x segment they share is coming from her maternal grandparents, but since her uncle only received his x from her maternal grandmother, then the segment comes from the niece's maternal grandmother.

                I suspect that the situation is the second one, since both the niece and her father and uncle received her paternal grandmother's x unrecombined. If that were the case, I would think that the niece and your uncle would share almost the entire length of one of her x chromosomes. If the niece received a recombination of her maternal grandparents' x chromosomes from her mother and her maternal uncle only received one x chromosome intact from his mother (the niece's maternal grandmother), the niece and uncle would only share one or more segments on the x, not the entire length of the x.

                So, if I'm right and the niece's mother is the sister of the uncle, you can regard that shared x segment as coming from the niece's maternal grandmother. That information may be useful if you keep a spreadsheet of shared segments and try to label segments as coming from a specific grandparent.

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                • #9
                  Where niece and uncle share on X, they will be sharing DNA from one of the Uncles maternal Grandparents (nieces Great Grandparents)

                  Uncle only received his X from his mother which will be random recombination of his mothers two.

                  Following picture may help you visualize

                  Note as mentioned mtDNA and XDNA have nothing to do with one another, seperate DNA with different inheritance patterns.
                  mtDNA will only match between the two if nieces mother was sister to Uncle.
                  Attached Files

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