I am wondering if anyone knows whether there is a right to request a blood test in Texas as opposed to a buccal swab? Seems like it would be impossible to cheat the blood test whereas not so on the buccal swab. §160 of the Texas Family Code does not reference whether the party can request the specific method of testing. Anyone have access to precedent on this?
I am interested in the prospect of contamination of a DNA test. If there are two people’s DNA in a sample collected at a lab, say, for example you had someone else’s saliva in your mouth when they did a cheek swab - could this result in a false DNA analysis? Specifically, when they do the DNA testing, do they test one individual cell or separate out the DNA from a bigger sample of cells and randomly assign different markers from the sample to be measured? Does that question make sense?
(bolding mine)
IANAD (nor do I have any medical training or lab technician experience)
IMHO, I find it highly unlikely, that is even possible. :dubious:
The person having the ‘cheek swab’ done would have to have exchanged a copious amount of saliva with someone else immediately prior to the ‘swabbing’, for that to even be remotely possible. :eek:
reported for forum change
Define cheat.
Somebody seems very anxious about a paternity test. You might get better answers if you lay all your cards on the table in one thread instead of opening multiple ones. I’ll report this to see if the mods want to merge and maybe move this.
If there is DNA from multiple individuals in a test sample, you can easily tell. For a single subject, there will never be more than 2 alleles at any locus. If there are multiple subjects, there will be >2 alleles at some loci. If this happens, you throw out the results and start over.
It is technically possible to run a test from a single cell, but it adds substantially to the cost and complexity of the testing. It is only done if there are no other cells available to test.
For a paternity test there would be no need to isolate a single cell from a cheek swab sample. There are ample numbers of cells in the sample.
If a lab received a sample with donor cells from multiple individuals then it would be obvious. The test could be run again with a new sample. Similar confirmatory results could point to certain rare genetic conditions but it is more likely that the sample contains cells from multiple individuals.
Since this seems to be a request for legal advice on a specific case, let’s move it to IMHO.
I have also merged a second thread on DNA contamination, which is more of a GQ. However, since the question is obviously related to the legal one I’m leaving it in IMHO.
Colibri
General Questions Moderator
No idea if Texas law provides for demanding a certain kind of sample be taken for a paternity test.
I do know it is possible for even blood samples to produce confusing results and to appear to have come from more than one person. With the increasing amount of genetic testing being done we are finding more instances of genetic mosaicism, where one person is essentially made up of cells from two fertilized eggs which fused.
Of course, you can’t cheat a DNA blood sample test:
The link about saliva simply shows that some of the other kisser’s DNA is present - so it would be the “2 sources” sample as mentioned by previous posts. This presumes intense “french” kissing, obviously.
DNA tests for legal purposes are done differently. If you suspect the wife or girlfriend and just want a heads-up if junior is really yours, you can order your own kit and do a home swab of inside your cheek and the baby’s and send them in for a result. This will not be legally binding, and any subsequent court case will require a legal test. After all, if baby-daddy doesn’t want to pay support, he’s quite capable of doing a David Copperfield and switching the swabs with a bit of sleight of hand, even if he does the test right in front of mama.
In a legal test, the persons being tested are both swabbed by a medical professional; they ask for positive identification documents before making the swab. From what I’ve read, the swab is not a goop of saliva - the tools is slightly abrasive, and rubbed firmly against the inside cheek to get a decent number of skin cells. When done properly, there should be significantly more cells of the subject than any random contaminant. And… the med tech handles everything, so you can be sure the right person was swabbed, and the swabs were not interfered with before being tested. (I suppose if you could figure out how to glue someone else’s skin inside your cheek, that might work. I hope the tech will at least look inside the mouth and notice if something looks odd. not sure where you would geta 1x2 inch square of someone else’s skin - and again if a repeat test is ordered… and two if you don’t know which cheek will be swabbed.)
Of course, a good legally binding test will also swab the mother - simply to ensure the mother is not pulling a fast one by switching babies.
As the history of that case shows, Schneeberger successfully cheated the DNA blood test and got away with it for five years. He was only caught due to a repeated DNA test arising from a separate allegation.
I appreciate the link to the one about saliva in the mouth. I am rather confused because I found links online with people talking about contamination of DNA samples, and from what I have read, the sample taken from the mouth is suspended in a solution before being replicated. What I don’t get is whether contamination would actually be obvious, if there were two people’s saliva, or other bodily fluids, in the sample, or whether they might accidentally examine a random allele from one cell on one part of the test and it could be from the father, while another allele result is taken from the wrong DNA, whatever DNA is mixed in with his sample.
Regarding Schneeberger, I read that too. Somehow I doubt that happens all the time. =)
If they did receive a mixture of two people’s DNA, it would be so obvious that they would know right away, rather than just list out the allele lengths and send back the results with a non-match?
Yes, it would be obvious. Even if the contaminant is only in trace quantities.
German police once spent major effort attempting to track a presumed serial killer whose DNA appeared at multiple unrelated crime scenes. It turned out that the swabs were contaminated at the manufacturer by a hapless female technician whose DNA was contaminating crime scene samples all across a swath of Germany, Austria and part of France. The DNA tests being used easily detected the actual DNA from the crime scenes but also the contaminant DNA from this technician.
So they were only looking for her DNA, not the serial killer DNA?
They thought she was involved in multiple crimes across a broad area, and with differing co-conspirators.
Guess they never heard of Occam’s razor.
Well, I’ll be! :eek: