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  • Introduction to FTDNA X-Chromosome Segment Matching

    X-Chromosome Matching at FTDNA (P1 of 2)

    This week’s big release is X-Chromosome matching. We have fully integrated it into Family Finder matching.

    Here is the menu link to the Family Finder Matches menu.



    On the Family Finder Matches page, there is a filter to show only X-Matches.



    When you use the X-Match filter on a male Family Finder kit, you
    should get only matches from the maternal X-Chromosome.



    Next, like other Family Finder Matches you can expand the advanced bar for a match and click to add the match to the Compare in Chromosome Browser list.



    Matches are added to the Compare in Chromosome Browser list. You could go right to the Chromosome Browser by clicking on the compare arrow at this point.



    Next we can also go right to the Chromosome Browser.



    The Chromosome Browser also lets you filter the match list by X-Matches.



    Here are three immediate relatives. The first two share X-Chromosome DNA. The third (green) one does not.



    When we scroll down to the X at the bottom, we see that X-Matching is displayed for the first two but not the third.



    ...

  • #2
    Introduction to FTDNA X-Chromosome Segment Matching

    X-Chromosome Matching at FTDNA (P2 of 2)

    Moving to the Advanced Matching page, X-Chromosome matches have also been integrated.



    X-Match is an option that can be checked alongside other types of testing.



    I will let everyone know when this is pushed live. Enjoy! Please let me know about questions, bugs, or improvement requests!

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    • #3
      X-chromosome vs. family tree matches

      Basic questions:as a male, genetically speaking, is my relationship with my family tree matches closer than those stablished via x-chromosome matches? Are mtDNA matches genetically closer than x-chromosome matches? As you can read, I'm just trying to make sense out of the raw data. Thank you for your reply!

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      • #4
        Implications of a match on X?

        What are the implications of a match or lack of match on X? Is this part of autosomal DNA?

        Comment


        • #5
          http://www.thegeneticgenealogist.com.../NewChart5.jpg
          gives some probabilities for a male.

          A solid match on the X chromosome allows you to hone in on the lines that are most likely to give you a piece of the X for both you and your matching cousins.

          A match on the mitochondrial DNA can be very distant in the past, often hundreds to even thousands of years.

          The cousin-ship can be difficult to predict even with solid X chromosome matches. If you have many autosomal segments plus a strong X segment match (> 10 cM for example), then there often is an ancestor within a genealogical time frame that appears within the pedigree showing the X inheritance pattern.

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          • #6
            Originally posted by FranM View Post
            What are the implications of a match or lack of match on X? Is this part of autosomal DNA?
            There are 22 pairs of autosomes and a pair of sex chromosomes. The sex chromosomes (X and Y) are not autosomes. A male gets an X from his mother and a Y from his father. A female gets an X from her father and another X from her mother. The autosomes and sex chromosomes are all found in the nucleus of the cell and separate from the mitochondrial DNA.

            The X chromosome pattern of inheritance is similar to autosomal DNA but there can never be two males in a row (father to son) because a male does not give his X to his son. Rather, he gives his Y to his son. So if you want to find a common ancestor who carried the X, you need to map out your pedigree using only the X pattern of inheritance. If you are female, use the female focus chart here to list your ancestors:
            http://debbiewayne.com/search_custom.php

            You will see there are no two males in a row (son to father) going back in time. Entire lineages can be eliminated from the pedigree when trying to find an X ancestor in common.

            A lack of a match on the X does not mean much because some siblings will not match on the X. Full sisters always match each other however because they each match a whole X coming from the father. That is the only time you can rule out a relationship. You can't be full sisters without an entire X match. Females who are half-siblings cannot share a father unless they match a whole X chromosome.

            At FTDNA, the X has been added to the chromosome browser and you don't have to order any special test. Just look at your Family Finder results. Be sure to set the segment size higher than 5 cM (preferably 10 cM). Right now you can't just look at a strong match on the X without also having an autosomal match with the same cousin because there is no chromosome browser here that separates out the X matches from the autosomal matches. You would have to upload raw data to a third party site to look for X matches alone. Some people can match on the X without a significant match on the autosomes. Those people are not on your match list at FTDNA.

            Most X success stories involve lines that have given you both autosomal matches and X matches through some of the same ancestors during recent history. That is simply because you have more DNA in common (and more segments) with a closer cousin. X lineages certainly can be helpful in breaking through brick walls.

            Kathy
            Last edited by Kathy Johnston; 19th January 2014, 12:41 PM.

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            • #7
              Should two full sisters match exactly on the X chromosome?

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              • #8
                Originally posted by Tenn4ever View Post
                Should two full sisters match exactly on the X chromosome?
                Two full sisters should match one X chromosome from beginning to end (except perhaps at the very tips). They also usually have full matching segments where they match on both chromosomes. That is because their mother usually mixes her two X chromsomes before passing one to each daughter. The mother's X is rarely the same between the 2 daughters. The father's X is always the same. In the browser at Family Tree DNA you won't see the full matching segments. The entire segment is colored, hiding the difference between the chromosomes.

                If you upload the raw data from the two sisters to a third party site like David Pike's tool, you can visualize the double matching here:
                http://www.math.mun.ca/~dapike/FF23utils/

                There you should be able to see the segment start and end points coming from the mother listed as a double segment match.

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                • #9
                  Thank you Kathy.

                  Comment


                  • #10
                    Pas de X-matches de trouvés.

                    Bonjour.

                    Est-il normal que je n'ai aucun résultat lorsque je sélectionne X-Matches sur family finder?

                    Cordialement.

                    manuel Mahé

                    Comment


                    • #11
                      Originally posted by mjaMahé View Post
                      Bonjour.

                      Est-il normal que je n'ai aucun résultat lorsque je sélectionne X-Matches sur family finder?

                      Cordialement.

                      manuel Mahé
                      Yikes please use English.

                      Males will have less matches since males only have a single X chromosomes while females have two X chromosome. Males have a Y chromosome instead of a second X chromosome. Both males and females have two chromosomes for the autosomal chromosomes (1-22).

                      Also your X line might be from an ethnic group(s) that is not highly tested for example Polynesian.
                      Last edited by thetick; 6th June 2014, 09:36 PM.

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                      • #12
                        Originally posted by mjaMahé View Post
                        Bonjour.

                        Est-il normal que je n'ai aucun résultat lorsque je sélectionne X-Matches sur family finder?

                        Cordialement.

                        manuel Mahé
                        Translation in English: Is it normal that I have no result when I select x-matches on family finder?

                        Depending on the ethnic group, any males at FTDNA have no X results even at 1 cM. Females normally have a lot more because they have two X chromosomes. I believe females have more coincidental, identical by state matches.

                        Correction, misspelling "many males" not "any males"
                        Last edited by Kathy Johnston; 9th August 2014, 04:54 PM.

                        Comment


                        • #13
                          Bonjour.

                          Merci de vos réponses, mais l'histoire n'est pas très claire dans mon esprit. En effet, pourquoi ne puis-je pas localiser le chromosome X apporté par ma mère?

                          Cordialement.

                          manuel Mahé

                          Comment


                          • #14
                            Originally posted by mjaMahé View Post
                            Bonjour.

                            Merci de vos réponses, mais l'histoire n'est pas très claire dans mon esprit. En effet, pourquoi ne puis-je pas localiser le chromosome X apporté par ma mère?

                            Cordialement.

                            manuel Mahé
                            Translation:
                            "Hello there,

                            Thank you for your answers, but the story is not very clear in my mind. Indeed, why can I not locate the X chromosome contributed by my mother?

                            Best regards.

                            manual Mahe"

                            ---
                            Hello Manual Mahe,

                            Your X chromosome is entirely from your mother, so it should be already located in you and it will be in the raw data. You have to download the X raw data separately. Your Y chromosome came from your father if you are a male.

                            Did you order a test for your mother at Family Tree DNA? If so, does she match you? If she is your mother, she should match you on her X chromosome. Did you look in the section where you see Family Finder Matches? First click on "Show Full View" then "Compare in Chromosome Browser". FTDNA is still showing a couple regions of mismatching between parent and child which is in error. If you go directly to the browser, sometimes the filter does not show "Immediate Relatives" so make sure your closest matches are showing.

                            The X that you have only came from your mother if you are a male. She mixes her two X chromosomes before passing one to you. The X that you received from her could be a mixture of the X coming from her mother and the X coming from her father. You can't tell which grandparent the different sections came from unless you have more information from the grandparent or a relative. Occasionally it will only come from one grandparent. The chromosome browser cannot tell which marker goes on which X chromosome in your mother. It will only show a match. If a grandmother raised you instead of a mother, that could show a non-match.

                            Many males are worried when they have no X chromosome matches with other people. That is common at FTDNA. But you will always match your mother.

                            I am not sure what you are asking. If you are looking for raw data, be sure you download the X chromosome and not just the autosomal DNA.

                            Please clarify.
                            Kathy

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                            • #15
                              is it truly a match on X if low numbers ?

                              GEDmatch.Com X-DNA Comparison

                              Comparing Kit A427033 (*svespa)(M) and A061003 (*Hazel)(F)

                              Minimum threshold size to be included in total = 100 SNPs
                              Mismatch-bunching Limit = 50 SNPs
                              Minimum segment cM to be included in total = 1.0 cM


                              Chr Start Location End Location Centimorgans (cM) SNPs
                              X 1984664 2875296 6.2 163
                              X 12820540 13348788 2.1 107
                              X 50818573 53426560 1.7 141
                              X 55052282 67094485 1.3 329
                              X 100053795 101784780 2.0 196
                              X 109310685 111348168 2.6 147
                              X 145106967 145975176 2.0 135
                              X 146500671 148406917 3.7 251
                              Largest segment = 6.2 cM
                              Total of segments > 1 cM = 21.5 cM Actual.

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