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  • Chromosome Browser Data?

    I had 216 matches before the Build 36/37 conversion and lost 2, so 214 remain. Of these, 211 have minor changes in the start/end points, but all 211 have identical (before and after) longest segments and SNP counts. I was using the CB file downloaded with DNATools, so checked manually using the FTDNA CB just to be sure. The 1st 10 I checked were identical to the Build 36 numbers. I could manually check more, but think it is pretty clear that my data is still not correct. It seems to me that changing the start and end points of the segment would change the SNP count. Has anyone else notice this? If I am wrong, could someone explain it to me in small words, short sentences and very slowly.

    Thank you.

  • #2
    Originally posted by teyoung View Post
    I had 216 matches before the Build 36/37 conversion and lost 2, so 214 remain. Of these, 211 have minor changes in the start/end points, but all 211 have identical (before and after) longest segments and SNP counts. I was using the CB file downloaded with DNATools, so checked manually using the FTDNA CB just to be sure. The 1st 10 I checked were identical to the Build 36 numbers. I could manually check more, but think it is pretty clear that my data is still not correct. It seems to me that changing the start and end points of the segment would change the SNP count. Has anyone else notice this? If I am wrong, could someone explain it to me in small words, short sentences and very slowly.

    Thank you.
    I wouldn't expect the SNP count to change (unless FTDNA changed their definition of "blocks"). Build 37 is a new reference sequence, which can change the position of the SNP on the chromosome, e.g. if some gaps in the "complete" sequence have been filled in. The SNP probes are looking for a short sequence of DNA around the position of interest, and they don't care about whether the position in the reference sequence is 31577266 or 32943398. We like to have those numbers to draw the segment boundaries on a chromosome map, though.

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    • #3
      The build 37 match pool starts at:

      3384.31cM
      706319 SNPS

      not including X chromosome data.

      I don't remember what build 36 was, I posted that too a long time ago.

      There should be more SNPs now because when FTDNA started the FF testing, they did not count all of the SNPs but took some out when downgrading build 37 to 36 (yes that's right, but its a long story).....


      Matt.

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      • #4
        Originally posted by mkdexter View Post
        The build 37 match pool starts at:

        3384.31cM
        706319 SNPS

        not including X chromosome data.

        I don't remember what build 36 was, I posted that too a long time ago.

        There should be more SNPs now because when FTDNA started the FF testing, they did not count all of the SNPs but took some out when downgrading build 37 to 36 (yes that's right, but its a long story).....


        Matt.
        Hmmm... my Build 36 downloads have 708092 SNPs.

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        • #5
          Originally posted by Ann Turner View Post
          I wouldn't expect the SNP count to change.
          Thank you, Ann. I guess I am having a difficult time wrapping my head around the concept that moving all these SNPs around would not redefine the matching segment.

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