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A question about mitochondria DNA and X chromosomes

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  • A question about mitochondria DNA and X chromosomes

    My mother and aunt have the same mitochondria DNA. Just like their mother and their mother's mother. And since I'm her male child I have the same mitochondria DNA too. My question is do I automatically have the same X chromosome as my grandmother on my mother's side? Or could it be from my mother's father? I guess what I mean is does the mitochondria DNA travel along side with the X chromosome, or are the mitochondria DNA and X chromosome one and the same so to speak?

  • #2
    No the X has a very special inheritance pattern. It is not passed from father to son. A son inherits his X from his mother, but what he gets from her is a combination of what she got from each of her parents. On the average, you got half of what each of your maternal grandparents gave to your mother.

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    • #3
      OK I know since I'm a male I don't get my father's X chromosome. But which X chromosome do I get from my mother? The one she got from her mother? Or the one she got from her father? Or basically a combination of the two?

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      • #4
        Originally posted by twang View Post
        Or basically a combination of the two?
        Yes, your X could be a combination of your mother's two X chromosomes. That's why we can't use the X to trace a known direct line like we can with the Y and mtDNA.

        Elise

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        • #5
          Females have two X chromosomes, one inherited from the father and the other from the mother, so the connection could be from either side of the family. Males have one X chromosome, inherited from the mother. SMGF has a nice animation showing the inheritance pathway:

          http://www.smgf.org/education/animat...hromosome.jspx

          Since not all ancestors can make a contribution to the X, you can eliminate at least some of them as possibilities. See the diagrams on Blaine Bettinger's site:

          http://www.thegeneticgenealogist.com...-x-chromosome/

          http://www.thegeneticgenealogist.com...mosome-charts/

          Note that the percentages are AVERAGES. A man's X chromosome can be exactly the same as his maternal grandfather, exactly the same as his maternal grandmother, or a mixture of the two, which works out to be average of 50%.

          If your genealogy program can print an ahnentafel chart, I've prepared a file with the relevant ahnentafel numbers. Females should start the ahnentafel with themselves; males should start with their mothers. Then you can go through the ahnentafel report and delete the records of the people who could not be the source of your X.

          http://dnacousins.com/AHN_X.TXT

          Ann Turner

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          • #6
            Originally posted by Ann Turner View Post
            A man's X chromosome can be exactly the same as his maternal grandfather, exactly the same as his maternal grandmother, or a mixture of the two, which works out to be average of 50%.



            Ann Turner
            Thank you. I never knew that before. No wonder we human beings are so diverse.

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            • #7
              Males get their X from their mother. She gets hers from both her father and her mother one each. 25% of your tree on your mother side could be the downer. You can eliminate any path where its father to son only consider father to daughter or mother to daughter.

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              • #8
                Originally posted by twang View Post
                My mother and aunt have the same mitochondria DNA. Just like their mother and their mother's mother. And since I'm her male child I have the same mitochondria DNA too. My question is do I automatically have the same X chromosome as my grandmother on my mother's side? Or could it be from my mother's father? I guess what I mean is does the mitochondria DNA travel along side with the X chromosome, or are the mitochondria DNA and X chromosome one and the same so to speak?
                Not sure you ever got your answer about the mitochondria part of your question. Your DNA and your mitochondria's DNA are separate in one sense because they are from different parts of your cells.

                Mitochondria travels in the cell cytoplasm and actually has its own DNA. The DNA we think of, our 23 pairs of chromosomes, travels in the cell nuclei.

                It is copied from a mother to her egg cell to her child. Since mitochondria has its own DNA SNP tests are conducted on it to determine its readings and haplogroup.
                Last edited by mkdexter; 7 August 2011, 08:19 PM.

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                • #9
                  Thank you mkdexter.

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