Announcement

Collapse
No announcement yet.

No X Matches - What does it mean?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • No X Matches - What does it mean?

    Hi,

    I have no X matches. If this is correct, can I draw any conclusions from that?

    For example, might I conclude that there aren't very many descendants on the X line that tested with FTDNA?

    Might I also conclude that Autosomal relations would be less likely found along the X lines (i.e X DNA inheritance lines)?

  • #2
    Originally posted by Joel View Post
    Hi,

    I have no X matches. If this is correct, can I draw any conclusions from that?

    For example, might I conclude that there aren't very many descendants on the X line that tested with FTDNA?

    Might I also conclude that Autosomal relations would be less likely found along the X lines (i.e X DNA inheritance lines)?
    The answer to the first question is that you must be a male if you have no X matches at FTDNA. Males have only 1 X so that lowers the chance for pseudo-segments (false segments). Females have a lot of pseudo-segments when the threshold is lowered to 1 cm. Two chromosomes have a much higher propensity for matching in a coincidental manner because the software combines the allele results from each of the chromosomes to make the call.

    I looked at a large FTDNA project to see how many of the males had X matching. I found that by the end of April, 2014, 6% of men in our project had no X matches. 50% of men had only 1 to 5 X matches. Those men who had over 100 X matches were of the Ashkenazi diaspora. Women tended to have lots of matches but these were less sensitive. Females need to increase the threshold probably higher than 10 cM.

    You may still get some autosomal matches along the X chromosomal lines. You cant rule those lines out, but if you eventually get a close relative with both autosomal and X matches, then you should take the X pattern of inheritance really seriously.

    Comment


    • #3
      My cousin is a female and she only has 1 X match over 10 cM. The same holds for my mother. They have the same X match. I attribute this to this to the fact that all ancestors from whom we could have received our X chromosomes immigrated to the United States after 1840 from Germany and France. My cousin's mother and my father were siblings, children of Italian immigrants. My mother's father's father was of Colonial American ancestry, but neither she or her siblings could get any X chromosome DNA from him. All other lines were recent immigrants. We not only have only one X match among these immigrant lines, we have very few autosomal matches either. As far as I can figure out most of the autosomal matches my mother has are in the line of the one grandparent with Colonial American ancestry. I think few German and French people have tested, especially from small villages.

      Do you have largely immigrant ancestry?

      Comment


      • #4
        My wife has 7 pages of X matches out of 39 pages of Family Finder Matches. I have none out of 80 pages of family finder matches.

        My mother's dad was an immigrant from Latvia (German). My mom's mother was in Philadelphia, but they had been around since the Revolutionary War. So I would think there would be some X Chromosome potential there. My mom had another Grandmother b. in Sheffield in 1865 and came here as a young girl.

        Joel

        Comment


        • #5
          Originally posted by Joel View Post
          My wife has 7 pages of X matches out of 39 pages of Family Finder Matches. I have none out of 80 pages of family finder matches.

          My mother's dad was an immigrant from Latvia (German). My mom's mother was in Philadelphia, but they had been around since the Revolutionary War. So I would think there would be some X Chromosome potential there. My mom had another Grandmother b. in Sheffield in 1865 and came here as a young girl.

          Joel
          Joel, I think if you increase the threshold to 10 cM for your wife, she will lose almost all of these matches. If 18% of her autosomal matches also have X matches, that sounds about right for most women when the threshold is only 1 cM. It will diminish considerably if you raise the threshold. Unfortunately the list of people matching your wife is an unrealistic match list. When I checked a few months ago (end of April) a non-Ashkenazi female had an average of 105 X matches out of 492 total FF matches (21%) in our project. Most of these disappeared when the threshold was increased.

          The databases need to be large for the importance of the X to be fully realized. There have been some amazing success stories especially for adoptees, but you have to be lucky. For a male, the X is only one chromosome out of a total of 45 chromosomes that are tested in FF (22 pairs plus one X). If your 80 pages of family finder matches were phased as well as a male's X, you might lose a lot of these autosomal matches too because of false positive identical-by-state matches. You have to have an autosomal match before an X is even reported so that tends to create a loss of significant X matches by design. Some of these might show up at GEDmatch.

          I think most of your autosomal matches must be from the Colonial population if you have 80 pages. It is possible that your X is almost entirely from Latvia. Your mother does not have to mix her two Xs very well but I can't really say that a "Latvian" X is the culprit. My father has 83 pages of autosomal matches but only a single X match (besides me) and this is with a female = 2.65 cM. He should be largely North American Colonial on the X but he did have one more recent X-line ancestor from East Anglia in England. To be successful, we need to meet a critical mass in terms of numbers of people testing. We clearly need to include closer cousins overseas and recent immigrants. I believe there are many pockets where people have not been tested.

          Comment


          • #6
            Originally posted by Kathy Johnston View Post
            Joel, I think if you increase the threshold to 10 cM for your wife, she will lose almost all of these matches. If 18% of her autosomal matches also have X matches, that sounds about right for most women when the threshold is only 1 cM. It will diminish considerably if you raise the threshold. Unfortunately the list of people matching your wife is an unrealistic match list. When I checked a few months ago (end of April) a non-Ashkenazi female had an average of 105 X matches out of 492 total FF matches (21%) in our project. Most of these disappeared when the threshold was increased.

            The databases need to be large for the importance of the X to be fully realized. There have been some amazing success stories especially for adoptees, but you have to be lucky. For a male, the X is only one chromosome out of a total of 45 chromosomes that are tested in FF (22 pairs plus one X). If your 80 pages of family finder matches were phased as well as a male's X, you might lose a lot of these autosomal matches too because of false positive identical-by-state matches. You have to have an autosomal match before an X is even reported so that tends to create a loss of significant X matches by design. Some of these might show up at GEDmatch.

            I think most of your autosomal matches must be from the Colonial population if you have 80 pages. It is possible that your X is almost entirely from Latvia. Your mother does not have to mix her two Xs very well but I can't really say that a "Latvian" X is the culprit. My father has 83 pages of autosomal matches but only a single X match (besides me) and this is with a female = 2.65 cM. He should be largely North American Colonial on the X but he did have one more recent X-line ancestor from East Anglia in England. To be successful, we need to meet a critical mass in terms of numbers of people testing. We clearly need to include closer cousins overseas and recent immigrants. I believe there are many pockets where people have not been tested.
            Thanks, Kathy,

            I am having trouble figuring out how to change the cM level on the X Chromosome other than downloading the results to Excel and sorting it out that way. My wife's X Chromosome matches are 17.5% of her total matches. She has a lot of Canadian ancestors, but many of them have apparently tested or migrated South. When I cut off my wife's X Match Excel list of Longest Block to 10 cM, her X Matches go from 66 to 27.

            It seems like you have figured out my situation correctly. I do have some colonial ancestors - through my great-grandmother. I haven't figured out how to get Gedmatch working yet, so no luck there. It keeps saying my kit was not tokenized. Now it is saying I should upload again.

            I have ordered a kit for my 90+ year old mom, so we'll see what happens there.

            Thanks for your help,

            Joel

            Comment


            • #7
              One addition. If I choose my wife's 5 closest X Match relatives and put them in the Chromosome Browser and choose 10 cM, only her 1st cousing once removed shows up on the bottom X level. I think this is what you were referring to.

              Comment


              • #8
                So I finally checked my X matches at gedmatch as recommended by Kathy. One strange thing there is that ATDNA < 5 cM shows as 0 until you compare them. Many of the submitters had German sounding names, so that seemed right. I don't recall seeing any with gedcoms but will look again and Will probably write to a few to see what happens.

                Forgot to mention, I got quite a few results on gwdmatch corresponding to all chromosomes except for 21 and 22.
                Last edited by Joel; 22nd October 2014, 04:11 PM.

                Comment

                Working...
                X