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  • single SNP only after Y-DNA?

    Sorry if this is a dumb question. Why is it necessary to order a Y-DNA test before you can order a single SNP test?

  • #2
    Once you've tested at least 12 yDNA STRs, FTDNA will predict your haplogroup. If they can't confidently predict your haplogroup, they'll do a free backbone SNP test to predict your high level haplogroup, which might be R1b, J2, etc.

    How would you know which single SNP to order if you haven't tested any STRs and had your haplogroup predicted? I suppose if your father, brother or one of your father's brothers had already tested some STRs, you could infer that you have the same haplogroup. But what if the man you think is your biological father or brother is not? When you ordered a SNP based on his results, you would probably end up being negative for it.

    Also, single SNP tests are not the preferred SNP test any longer. They've been mainly replaced by SNP packs and Big Y. Those tests can tell you your status for many more SNPs at an economical price/SNP, compared to ordering SNP by SNP singly. There may be a few situations where it makes sense to order a single SNP, but those would mostly be cases where you've already had a SNP pack or Big Y test done and need to check your status on a specific SNP the test didn't cover.

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    • #3
      Lets say my brother did the Big Y, and I just want confirmation of the terminal SNP. Thanks for your response.

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      • #4
        Originally posted by whgrant3 View Post
        Lets say my brother did the Big Y, and I just want confirmation of the terminal SNP. Thanks for your response.
        In that case, testing a single SNP is a viable plan. However, you still run the risk of uncovering that you and your brother don't have the same father, if you don't match any of his private SNPs or even an upstream SNP. But that's useful, although shocking, information to get from a test.

        For the reasons I mentioned in my first post, FTDNA does not allow customers to order a SNP test without first having tested STRs. You can call their customer support number - scroll down to the bottom of the page - and see if you can convince them to make an exception in your case.

        The other option is to send a DNA sample to another testing company, YSEQ, which is run by the former director of FTDNA's lab. This is the only other testing company that does yDNA testing. You can check their SNP menu to see if they test for your brother's Big Y SNPs. If so, send them a sample and order the SNP. If not, your brother can get them to add his SNPs to their menu. He'll have to give them the location of the SNP and the ancestral and derived calls. Then they'll see if they can develop primers to test for it successfully.

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        • #5
          I did talk to someone who said Y-DNA must be tested first but I did not understand why. Also they are not advertising the 12 marker test but said it "is available" by calling in and requesting it.

          If another company can test the single SNP, then I see no reason that FTDNA can not also do that.

          I may call back and try explaining this better but I had hoped a scientific reason was behind the STR requirement.

          Thanks for your help.

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          • #6
            Originally posted by whgrant3 View Post
            If another company can test the single SNP, then I see no reason that FTDNA can not also do that.
            Just go with YSEQ. It's probably cheaper there too.

            Jack

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            • #7
              Originally posted by georgian1950 View Post
              Just go with YSEQ. It's probably cheaper there too.

              Jack
              Thanks for your comment. I tend to agree with you except that FTDNA already has my sample.

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              • #8
                Originally posted by whgrant3 View Post
                Thanks for your comment. I tend to agree with you except that FTDNA already has my sample.
                YSEQ might still be quicker and I believe its sample kit is only $3.00.

                Jack

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                • #9
                  Originally posted by whgrant3 View Post
                  Thanks for your comment. I tend to agree with you except that FTDNA already has my sample.
                  You can order the Y-DNA12 test through this page then leave the group once you place the order.
                  Last edited by Armando; 1st July 2017, 11:16 AM.

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                  • #10
                    Originally posted by whgrant3 View Post
                    Lets say my brother did the Big Y, and I just want confirmation of the terminal SNP. Thanks for your response.
                    Here's another complication in the scenario where your brother has already tested Big Y. If you want to test one of his private SNPs found in Big Y, you'll probably find that it's not offered in FTDNA's SNP menu. They would only add new SNPs which they expect more than one or two people would order, which would not be the case of a private SNP found in a Big Y test. You would probably find a more upstream SNP from your brother's Big Y results in their individual SNP menu, but that would take in more men and different surnames than your recent paternal line ancestry.

                    One thing I'm puzzled by is, if you haven't tested your yDNA at all, what are you hoping to prove by testing SNPs from your brother's Big Y test? Are you trying to confirm that you are in fact from the same paternal line and share the same father? That's the only goal I can think of in wanting to test your brother's Big Y SNPs.

                    If that's the case, considering all the hoops you're finding that you need to jump through, why not just have you and your brother both take the Family Finder test? That will establish with certainty that you are full siblings.

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                    • #11
                      Originally posted by georgian1950 View Post
                      YSEQ might still be quicker and I believe its sample kit is only $3.00.

                      Jack
                      Thank you. I will look into it.

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                      • #12
                        Well, yes, that is correct. I am also trying to save dollars on the confirmation. I do like your suggestion, except for the cost. Thanks again.

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                        • #13
                          Originally posted by whgrant3 View Post
                          Well, yes, that is correct. I am also trying to save dollars on the confirmation. I do like your suggestion, except for the cost. Thanks again.
                          If cost is the main thing in your mind, then make sure your brother's Big Y private SNPs (at least some of them) are made testable at YSEQ. Then order one or two of those SNPs for yourself after you've sent your DNA sample to YSEQ.

                          The alternative of both of you testing Family Finder would be $89 each, unless your brother has already had Family Finder done. You would save some money by going the YSEQ route if both of you have to order Family Finder or even if only you have to order Family Finder.

                          That's the way to go, if you don't mind the minor detail of getting your brother's Big Y private SNPs made testable at YSEQ. As I mentioned previously, you or your brother would have to provide YSEQ with the location and ancestral and derived calls for the SNP. That information is available in in the raw data (VCF file) of your brother's Big Y results.

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