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Spoke with T.Krahn- explination how X-Testing works

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  • Spoke with T.Krahn- explination how X-Testing works

    I spoke with T. Krahn about X-Testing-Answer

    Men get 1 X gene from their mother so when they pass the X down a daughter it has no chance to recombine with another X because he has XY.
    All females from the same father will share the same X.

    A woman who has 2 X one from mother and one from father. When she passes her X down to her children they will recombine so each sibling will recieve a different X from their mother.

    He said it is very rare, he gave me 3% chance, that a woman's 2 X will not recombine and she will pass the same X to her children.

  • #2
    But the degree of recombination of maternal X can be quite modest, evidently, as shown by my match to my younger sister. We got pretty much the same X from our mother except for differences at just two loci, 6807 and 981.

    Our eldest sister is now testing. Her results will confirm the paternal X, resolve the ambiguity at the two loci, and, hopefully, produce additional alleles attributable to our mother.

    We are posting, progressively, whatever we find of the maternal diplotype on Xmatch at DNA-F under user name Dorothee. It will be, to some degree, a Native American X.
    Last edited by tomcat; 10 October 2007, 01:30 PM.

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    • #3
      So surely X testing could help daughters who don't know their fathers to get an idea of the ethnic background of the father's mother?
      I understand that the daughter won't know which x came from which parent, but suppose the paternal Grandmother was Native American? Would her x tell show up as such if the other x was say European?
      I spoke to whichever company it is who does the testing and they told me that it can't do this. If that is the case then what is the point of it?
      Last edited by burto; 10 October 2007, 01:40 PM.

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      • #4
        Originally posted by burto
        So surely X testing could help daughters who don't know their fathers to get an idea of the ethnic background of the father's mother?
        I understand that the daughter won't know which x came from which parent, but suppose the paternal Grandmother was Native American? Would her x tell show up as such if the other x was say European?
        I spoke to whichever company it is who does the testing and they told me that it can't do this. If that is the case then what is the point of it?
        Actually, if a brother and sister from the same parents do x chromsome testing, you can discover which x in the daughter is from her father. The son will have his only x from the mother. Theoretically, the daughter will have that same x from her mother. It seems logically that the daughter's other x must be from her father.

        Someone please correct me if I have it wrong.

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        • #5
          X test

          Originally posted by MMaddi
          Actually, if a brother and sister from the same parents do x chromsome testing, you can discover which x in the daughter is from her father. The son will have his only x from the mother. Theoretically, the daughter will have that same x from her mother. It seems logically that the daughter's other x must be from her father.

          Someone please correct me if I have it wrong.
          Mike,

          I did the X test to prove my father because he is deceased. My sister and I match exact on one side because we have diffrent mothers.

          My father also had a brother. T.Krahn told me this lowers my % of paternity from 99.999999 % to 97 %. He told me there was a Very Rare chance ( 3% ) that my grnadmother's X did not recombine and that both my father and his brother would get the same exact X.

          It just so happens that my sister and I shared 2 of the same #' on one marker and can not tell which marker is my mother's and which is my fathers.

          Tom stated his sister's have a diffrence in a few markers on their mothers side because of recombination. He is waiting to see what his other sisters test brings. She may have a few diffrent recombining markers also.

          My Uncle took the X but none of his sisters will test to see if they would match on one side or not. If my Uncle matched one of his sisters exactly, that means their mother's X did not recombine and is in the rare 3%.

          I hope this makes sense!

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          • #6
            Ethnic Backround

            Originally posted by burto
            So surely X testing could help daughters who don't know their fathers to get an idea of the ethnic background of the father's mother?
            I understand that the daughter won't know which x came from which parent, but suppose the paternal Grandmother was Native American? Would her x tell show up as such if the other x was say European?
            I spoke to whichever company it is who does the testing and they told me that it can't do this. If that is the case then what is the point of it?
            Burto,

            The X test my sister and I match exact on one side ( Father ) we have different mothers.

            As far as predicting ethnic backround. We know that my father's mother was NA and Irish. Does my X on my father's side match up to this? I don't know. The more people that X test and post their X test at DNA-F, the more study they can do on the markers for ethnic backround. In just playing with my markers and comparing what is available on line, I seem to have a lot more rare markers on my mother's side. My mother's side does have a lot more NA than my father's from what I know of. We have questioned weather my Grandfather on my father's side had NA but at this time we do not know for sure.
            Last edited by Yaffa; 10 October 2007, 02:56 PM.

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            • #7
              Forgive this basic question, but what "x test" are you speaking of? Is this different from the mtDNA haplogroup test? Is this the same as the autosomal?

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              • #8
                Female somatic X's, the type of X harvested by buccal swab, are perfect copies of the two X's received from her parents. She got one X from her father and one from her mother.

                Her mother's X's are all recombined products of the two X's the mother got from her parents. X recombination occurs in females in ovo-genesis only. In somatic cells one X is always inactivated so the two X's present cannot interfere with one another in X chromsome functioning.

                The paternal X that is somatically preserved in the daughter was also preserved in the father because males have only one X and so can never recombine. That paternal X came to the father from his mother, the paternal grandmother. And although it was an X recombined by the grandmother it is nevertheless a generation-jumping genetic signature of the paternal grandmother.

                Because all children can get a slightly different recombo X from their mother, but daughters always get the same 'preserved' X from their father, the best way to sort-out family X-lines is to test two sisters. Their common X is the paternal X haplotype (from grandma). All other X's are various versions of the two maternal X's.

                However, the three X markers known to be in linkage disequilibrium (DXS 10074, 10075, and 10079) always descend in a block and are thought to hang-together for generations.

                So, with a sufficiently large X database, it is imagined that particular blocks will be linked to specific ancestries.

                In our testing so far, we have ID'd the paternal X block and seen one maternal X block twice. We are looking for the other maternal X block and as many other maternal X alleles as we can find.

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                • #9
                  X testing

                  Originally posted by tomcat
                  However, the three X markers known to be in linkage disequilibrium (DXS 10074, 10075, and 10079) always descend in a block and are thought to hang-together for generations.

                  So, with a sufficiently large X database, it is imagined that particular blocks will be linked to specific ancestries.

                  What Tomcat said is important.
                  < DXS10074, 10075 and 10079 descend in a block. >

                  They are transmitted without recombination (maybe during many generations). These three STRs are located within a 280-kb region at Xq12.

                  So, some haplotypes are maybe found in some regions and rare or even absent in other regions of the world. If it's the case it will be informative.

                  There is an interesting paper about that. You can find it at:
                  http://www.springerlink.com/content/763717j1850667w6/

                  Nordvarg

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                  • #10
                    Originally posted by vinnie
                    Forgive this basic question, but what "x test" are you speaking of? Is this different from the mtDNA haplogroup test? Is this the same as the autosomal?
                    X is one of the 'sex chromosomes' the other is Y. X is a completely different animal than Mt-DNA, although in some populations that have a predominant Mt haplogroup and are not admixed one might expect to find a limited number of X haplotypes especially as regard the haplo blocks of markers DXS 10074, 75, 79.

                    X is semi-autosomal because it has a slower recombination rate than the autosome.

                    Try it, you'll like it!

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                    • #11
                      [QUOTE=Nordvarg]What Tomcat said is important.
                      < DXS10074, 10075 and 10079 descend in a block. >

                      Hi!
                      To emphasize what Tomcat says is indeed important(above quote) I want to say that my sister & I received our father's DXS10074,10075 and 10079 from our father..we receive the same X markers and they are: 15,16,16

                      Again quite importantly for me is that this IS my Dad's haploblock..since Dad is deceased and his father is unknown to us , this all we have of Dad's Mother's family..my Carrows..I can hopefully use this to match with cousins or compare in geographic regions..

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                      • #12
                        Dxs10074, 10075, 10079

                        [QUOTE=Kathleen Carrow]
                        Originally posted by Nordvarg
                        What Tomcat said is important.
                        < DXS10074, 10075 and 10079 descend in a block. >

                        Hi!
                        To emphasize what Tomcat says is indeed important(above quote) I want to say that my sister & I received our father's DXS10074,10075 and 10079 from our father..we receive the same X markers and they are: 15,16,16

                        Again quite importantly for me is that this IS my Dad's haploblock..since Dad is deceased and his father is unknown to us , this all we have of Dad's Mother's family..my Carrows..I can hopefully use this to match with cousins or compare in geographic regions..
                        Hi kathleen,

                        Yes those markers are very important since they do not recombine. But I just want to note for kinship between sisters on father's side,all 16 markers have to match. This is what T. Krahn told me.

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                        • #13
                          Not the same...

                          You know mtDNA, y DNA, autosomal dna and then there is X DNA. This is not the mtDNA Haplogroup X. This is totally different. This is one of the sex linked chromsomes. You know XX and XY. Female and male. This is the X part, 2 for female one for male. I had mine done but don't know how to use it. So I haven't concentrated on it that much. Doesn't have a big database yet. I had 16 different X str done between the 2 panels. I think it was about $9.00 for each one.

                          Maria

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                          • #14
                            My x markers...

                            Panel 1
                            dxs10011 31.2 and 40.
                            dxs10066 13 and 14.
                            dxs10067 16 and 18.
                            dxs10068 18 and 23.
                            dxs10069 16 and 17.
                            dxs10031 9 and 9

                            Panel 2
                            dxs10074 13 and 15.
                            dxs10075 17 and 18.
                            dxs10079 17 and 21
                            dxs10132 11 and 11.
                            dxs6807 11 and 15.
                            dxs7132 13 and 15
                            dxs7423 15 and 16.
                            dxs8377 44 and 46
                            dxs981 14.3 and 15.3
                            HPRTB 13 and 14.
                            Eventually I will test my mother and see which markers are hers.

                            Maria

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                            • #15
                              My x markers...

                              Double post!

                              Maria

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