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  • X chromosome PF painting

    If a male child inherits his mothers X chromosome… How can the chromosome paintings be different?

    Image is from Dr. McDonald analysis
    Attached Files

  • #2
    That's funny!

    You will have to ask Doug McDonald about that one, since its his chromosome painter.

    Keep one thing in mind, the son has a X from his mother but his mother has XX, one from each of her parents.

    The possible outcome for the child (son or daughter) is the following:
    1. Inherits all of the X from his mother's mother, none from her father
    2. Inherits all of the X from his mother's father, none from her mother
    3. Inherits a portion of X from his mother's father and mother.

    The only way I could see this happening, barring any issues with the chromosome painter, is that the mother's reading is leaning to one of her parent's X she inherited while the son is leaning to the other of his mother's parents. I'm not sure this is possible for McDonald's painter though, you would have to ask him.

    Matt.

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    • #3
      Neves let us know what Dr. McDonald has to say that does seem odd.

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      • #4
        Originally posted by Neves View Post
        If a male child inherits his mothers X chromosome… How can the chromosome paintings be different?

        Image is from Dr. McDonald analysis
        I'm going to write down information that comes to my mind initially, and then let others discuss it more fully:

        (1) Your mother has two X chromosomes and they are not alike.

        (2) The one X chromosome you inherited is not exactly like either of your mom's X chromosomes because recombination (between the 2 X's) has been going on in her immature egg cells. (Correct me if I am wrong readers: Some of that recombination was going on in her immature egg cells before she herself was even born.)

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        • #5
          Cross-over does not always occur.

          If you look at is in terms of both maternal grandparents, or both paternal grandparents, almost everyone will find they have a few chromosomes that match one of their grandparents and not the other grandparent , and then they will find some that match both grandparents.

          The chromosomes that match both (maternal or paternal) grandparents are the result of cross-over, the chromosomes that match only one grandparent, but not the other, did not cross-over, they simply inherited one or the other of the pair from their parent.

          The enclosed is a grandson compared to both paternal grandparents. Look at chromosomes 3, 7, 9, and 20. Those had no cross over, the others where two colors appear on the same chromosome did have cross-over, thus both colors, and they cross-over where the colors change.

          Matt.
          Attached Files
          Last edited by mkdexter; 25 November 2012, 02:52 AM.

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          • #6
            Originally posted by mkdexter View Post
            That's funny!

            You will have to ask Doug McDonald about that one, since its his chromosome painter.

            Keep one thing in mind, the son has a X from his mother but his mother has XX, one from each of her parents.

            The possible outcome for the child (son or daughter) is the following:
            1. Inherits all of the X from his mother's mother, none from her father
            2. Inherits all of the X from his mother's father, none from her mother
            3. Inherits a portion of X from his mother's father and mother.

            The only way I could see this happening, barring any issues with the chromosome painter, is that the mother's reading is leaning to one of her parent's X she inherited while the son is leaning to the other of his mother's parents. I'm not sure this is possible for McDonald's painter though, you would have to ask him.

            Matt.
            I agree about asking Doug. It's possible that the reading for the mother is more ambiguous -- her genotype has two alleles for every SNP, which might be interfering with a clear-cut conclusion. The son's X chromosome is automatically a haplotype, so there's more clarity about which SNPs are traveling together as a package.

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            • #7
              Here is what Dr. McDonald said:

              [Why the X does not match: your mother has two X chromosomes, and you get only one. Thus, at that Mideast spot she must has one that has quite a bit, and one that has little, and you got the former one.

              The X is not used for anything except that painting.
              ]

              Taking into consideration that my mothers PF is 100% Orcadian.
              -Her recent family tree going back 7 generations is 75% English and 25% Danish.
              -The segment it is about 1/8th of the whole which would make it about 13%.
              -Comparing X chromossome inheritance pattern and percentages…

              My thoughts are that this must be a solid Danish portion of my maternal great grandparents. My maternal grandmother was half Danish, her mother was full. Perhaps there is a Jewish factor with her parents bringing in the middle east.

              When Dr. McDonald compared my results (autosomal) with my parents charts he said that I was way off the charts from my parents.

              [This one is either actually German, or some sort western-Eastern European mix.
              This is the child of the other two. A child ALWAYS gets exactly 50%
              of their autosomal DNA from each parent. HOWEVER, they don;t get
              exactly 25% from each grandparent. In this case the child is way off on the map from the average of the other two. This means that at least one grandparent had to be from Germany (Denmark) or east of that, and likely two (one maternal, one paternal) of them were.
              ]

              How often is “off the charts” likely to happen?
              only one grandparent was half Danish so do you think I inherited most of my grandmothers Danish side in order for him to think that I should have two full grandparents?

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              • #8
                Neves not sure how to answer the last part of your question. I have to admit I'm still kind of baffled by Dr. McDonald's response. Yes you only get the one X from your Mom's two X's that recombined to you. But why did his painting not paint that Mideast segment on your Mom's as well? As his X IS just for that painting.

                I think I like the way Ann Turner explained what may have happened.

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                • #9
                  @Neves it is possible to inherit a majority from one side and not the other but it is not as common as inheriting near 50% from each. My granddaughter matches 67% of my chromosomes, only 33% of my wife's.

                  I thought of something that we need to ask Doug McDonald about. FTDNA does not provide us with properly formatted X raw data. This is why John has to reformat it when a person uploads X to gedmatch.com. It is quite possible that there are some errors occurring on the X. This would depend on which SNPs are used out of the raw data and whether those SNPs need to be pre-adjusted or not like John has to do.

                  I suggest you load your kits to gedmatch (including the X) and compare them there on the various chromosome painters. You could even phase the one and use the opposite phased file (paternal) in the chromosome painters on gedmatch.com

                  Matt.

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