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blood on test swab

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  • blood on test swab

    I administer a group of descendants of Vaughans who have conducted quite a few Y-DNA tests and we are in the process of charting our ancestry. One of our new test subjects is an elderly man who takes blood thinner and while doing the cheek swab today his cheek bled some and he got blood on the swab. I know blood has Y-DNA in it, but I was unsure if this would mess up the test. He hasn't done the second test yet, and will try to be careful, but I wanted to find out before he does the second test.

    Eddie Davis
    List Administrator, Vaughan Pioneers Genealogy Research group

  • #2
    It appears that these swab tests yield either 99.9% accurate readings or no results at all. If the latter is the case then FT-DNA will send you another kit to do a re-swab.

    I once swabbed a person who was supposed to share the same g-grandfather with another I tested. When the results revealed the two participants a genetic distance of six on a twelve-marker test, I thought about the coffee that one had before his test and the tobacco that the other chewed! Upon a retest of the tobacco chewer, the same numbers proved the accuracy of these Y-DNA tests. Either they reveal complete accuracy or nothing at all.

    BTW, in most of the Y-DNA tests that I have administered, the participant is not available eight hours later for a second swab...especially if he is a stranger that I had never met before. I simply had the participant swab one cheek for 60 seconds and then the other cheek 60 seconds later. This goes against the instructions, but has never failed to produce results.


    • #3
      When I did my cheek swab I might have been a little over-enthusiastic, and I managed to make the inside of my cheek bleed on the swab too. I don't think it was a problem; I did get my results. Maybe they used the alternate swab, but I don't know. At any rate, the blood contains the dna too, so I can't imagine it would be a problem.