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Prenatal Paternity Testing Accuracy?

  1. Jan 1, 2014 #1
    I was a member here years ago and recall the excellent quality of the brain trust present and I need some brain power to give me some understanding of the situation I find myself in.

    Through a series of unfortunate events, the woman I was seeing had a brief encounter with another man. Here were the facts as we knew them before we got prenatal testing done, in general they pointed to this man not being the father:

    • The man she was with is approximately 50.
    • He reportedly had "slow swimmers" and required in vitro fertilization to get his ex-wife pregnant.
    • The dates when she was with me and him are very close together and her cycle was of no use to pinpoint anything.
    • I am much younger and healthier than the man she was with, and have no reproductive issues that would require in vitro or special assistance to conceive.

    So this left us feeling uneasy because through dates alone this man could not be ruled out but all things being equal I seemed more likely to have impregnated her. So we went with (ultimately) 2 companies to do prenatal DNA paternity testing to get more clarity on the issue. Company A took blood from her and I. They apparently had a good sample from me but required her to come back 3 times for additional blood samples because the results kept coming back as "inconclusive." After the 3rd time of her giving new blood samples they just told us they couldn't do it for some reason and refunded our money.

    So we contracted with company B who was better than company A (so said them, ha), and this time they got results the first time. They took about 8 vials of blood from her and did a mouth swab from me, no blood. They came back and said there is a 99.9% chance I am not the father and elsewhere on the paperwork, that there is less than a 1% chance I am the father.

    For various reasons, this was a complicated pregnancy and process and I think it has to do with her. For instance, one doctor had her getting shots because of her blood type, which is apparently Rh(-) and rare from what I have read. She got these shots so that her body would not reject sperm/dna/fetal development from an Rh(+) father. I am certain I am Rh(+). We just aren't really sure about her blood type and as crazy as that sounds to readers, she was going to like 5 different doctors and its easy to get things mixed up and not have communication between them. So although I am unsure of her bloodtype and much of the specifics, I can say this has not been a typical pregnancy and she seems to have atypical DNA or blood or something else. She became pregnant from me earlier this year and she lost this baby, possibly because of the blood type issue.

    I don't have anything from company A but company B did give me some paperwork so I will reproduce that here because someone else will know what it means much more than I do.

    • The sampling method was Bucall cells from me and blood from her.
    • "DNA was isolated from the buffy-coat samples of the mother and the buccal cells of the alleged father. DNA was sequenced at numerous single nucleotide polymorphisms (SNPs) located on multiple chromosomes throughout the human genome. The plasma DNA, which contains both fetal DNA and maternal DNA, was analyzed at the thirty two (32) informative SNPs."
    • "Among the thirty two (32) informative SNPs that were analyzed, eleven (11) fetal alleles did not match the alleged father."

    So the alleles did not match me, the alleged father, on 11 of the 32 alleles. Now I know the probability can't be as simple as dividing 11/32 here but I am unsure of how if 11 of 32 did not match they are able to conclude I am not the father with such high confidence (about 99%). What about the other 21 alleles?

    As I understand the testing process, they get fetal DNA from the mother's blood, which contains some circulating fetal DNA, and then compare that sample to me. This is also a relatively new method of testing and inherently not as accurate as doing the test with the born baby and myself, according to company B themselves. That test will be done in a few months when the baby is born for sure just to be certain.

    I have deliberately kept my emotions out of this post as it regards what I want the results to be so that I can get a more objective assessment from people on this forum. Thus, what are the chances of this test being much less accurate than claimed? What could have caused the issues with Company A that Company B seemed not to encounter if they do the same kind of testing? Is it really 99% likely that I am not the father or is this just an exuberant and overly optimistic advertising claim on behalf of Company B? Any other insight that could be given on this seemingly complicated paternity testing method? From what I can tell they do not accept these tests in court either as readily or at all when compared to traditional post-birth dna testing.

    Thanks so much for any additional clarity anyone can offer.
  2. jcsd
  3. Jan 5, 2014 #2
    Anyone have any insight into this?
  4. Jan 6, 2014 #3


    User Avatar

    Staff: Mentor

    We have no way of telling what is going on. I suggest that you just wait until the baby is born, since you seem to want the baby, and then have a paternity test done at that point if it concerns you.

    We cannot help you.
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