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Lots of 'presumed negatve' SNPs after Big Y?

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  • Lots of 'presumed negatve' SNPs after Big Y?

    I recently had Big Y testing done on my father. On the Haplotree and SNPs portion under his Y-DNA results section, most of the SNPs in the visual tree are shown in black text (meaning they are presumed negative based on positive results elsewhere). Shouldn't most/all of these now be known to be either positive or negative now that Big Y testing has been done. At the bottom of the screen on this page, under "Tests Taken," it shows a list of positive SNPs. This is obviously too small (maybe 300 SNPs listed here?) to even be just a list of all the named variants found in the Big Y test. So what dictates what SNPs get listed at the bottom of this screen, and why are most of the SNPs listed on the Haplotree color coded as just 'presumed' negative?

  • #2
    I have high quality results from another company and the SNPs were named from my test. ftDNA says they're low quality or doesn't list them at all. I think the problem is ftDNA quality control and "not so bigY" coverage.

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    • #3
      We are not sure how FTDNA counts SNPs. I don't know
      exactly where they have the root. A person who tends the
      Haplogroup A and B projects would likely know if they have access anything K or later.

      Using ISOGG data for the main tree trunk and my own measurements for SNPs
      between I and P2 (the junction of Q and R) and from P2 to a living people in Q, R1a and R1b,I get
      typically 1080 reliable SNPs between
      a Y-Adam and any living person.

      I measure 435 SNPs between an I person and P2 (which means
      about 217 between IJK and a living person),
      221 between P2 and a Q person, 197 P2 to an R1b person and
      209 from P2 to an R1a person.

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      • #4
        Originally posted by adamjh View Post
        I recently had Big Y testing done on my father. On the Haplotree and SNPs portion under his Y-DNA results section, most of the SNPs in the visual tree are shown in black text (meaning they are presumed negative based on positive results elsewhere). Shouldn't most/all of these now be known to be either positive or negative now that Big Y testing has been done? At the bottom of the screen on this page, under "Tests Taken," it shows a list of positive SNPs. This is obviously too small (maybe 300 SNPs listed here?) to even be just a list of all the named variants found in the Big Y test. So what dictates what SNPs get listed at the bottom of this screen, and why are most of the SNPs listed on the Haplotree color coded as just 'presumed' negative?
        Okay. So I think I answered my own question by digging around in my Big Y results. There are definitely reliable SNPs in the Big Y results that are clearly positive or negative, but are just not indicated as such on the visual tree on the Haplotree and SNPs page in the Y-DNA results section of FTDNA. So it is kind of like the Big Y results area isn't really talking to that other FTDNA visual section (or at least it isn't a full conversation). There are plenty of SNPs(maybe most?) that are shown as 'Presumed Negative' on the Haplotree that are definitely negative in the Big Y results sections. Same story with the 'Presumed Positive' results.

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        • #5
          Originally posted by adamjh View Post
          Okay. So I think I answered my own question by digging around in my Big Y results. There are definitely reliable SNPs in the Big Y results that are clearly positive or negative, but are just not indicated as such on the visual tree on the Haplotree and SNPs page in the Y-DNA results section of FTDNA. So it is kind of like the Big Y results area isn't really talking to that other FTDNA visual section (or at least it isn't a full conversation). There are plenty of SNPs(maybe most?) that are shown as 'Presumed Negative' on the Haplotree that are definitely negative in the Big Y results sections. Same story with the 'Presumed Positive' results.
          I had noticed this with my results as well. The results of Big Y have not translated well to the visual representation on the Haplotree for me either. Probably a combination of my position on the tree and the haplotree's buggy interface anyway.

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