The DNA = Contamination.

Discussion in 'JonBenet Ramsey' started by Shylock, Jan 9, 2004.

  1. Shylock

    Shylock Former Member

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    This is a good article that explains how DNA is processed in the lab. It also documents how easily crime scene samples can be contaminated and cause false readings. Here is a couple parts of the article which relate to the Ramsey case:

    "Generally, RFLP analysis requires larger amounts of DNA and the DNA must be undegraded. Crime-scene evidence that is old or that is present in small amounts is often unsuitable for RFLP testing. Warm moist conditions may accelerate DNA degradation rendering it unsuitable for RFLP in a relatively short period of time.

    PCR testing often requires less DNA than RFLP testing and the DNA may be partially degraded, more so than is the case with RFLP. However, PCR still has sample size and degradation limitations. PCR tests are extremely sensitive to contaminating DNA at the crime scene and within the test laboratory. During PCR, contaminants may be amplified up to a billion times their original concentration. Contamination can influence PCR results, particularly in the absence of proper handling techniques and proper controls for contamination.

    PCR copies DNA efficiently if the initial DNA is in good condition. A single DNA entity (molecule) can become millions or billions of DNA molecules in about three hours. In this way, PCR is similar to what happens when a clinical infection occurs. Clinicians have known for many years that a single germ (bacterial cell or virus) contaminating a wound can produce a massive infection if untreated. Similarly, a DNA molecule can contaminate (infect) a PCR and become a significant problem. The ability of small amounts of DNA to produce false and misleading results is well known within the research community.

    Prevention of false results involves the use of carefully applied controls and techniques. As described later, such controls and techniques can sometimes detect contamination but cannot guarantee that contamination hasn't influenced the results."


    http://www.scientific.org/tutorials/articles/riley/riley.html
     
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  3. tipper

    tipper Former Member

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    DNA Testing: An Introduction For Non-Scientists
    An Illustrated Explanation

    by DONALD E. RILEY, Ph.D.
    University of Washington
    (Copyright 1998)

    Interesting article. Anything more current?
     
  4. Shylock

    Shylock Former Member

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    Contamination doesn't come with an expiration date.
    And poor collection/handling procedures in 1996 will still be considered such well beyond 2004.
     
  5. Britt

    Britt New Member

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    And DNA expert Kobilinksy cautions (in The Abrams Report interview about this case):

    LAWRENCE KOBILINSKY, PHD, DNA EXPERT: ...Now, I must say if they‘re using this special technology called low copy DNA, then it‘s a matter of interpretation. We have to be very careful because you can get some confusing results at times.

    http://msnbc.msn.com/id/3840387/

    Shylock, thank you for posting that article... very interesting.
     
  6. tipper

    tipper Former Member

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    True but when you're talking about amplification techniques then the age of the article is relevant.
     
  7. Britt

    Britt New Member

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    DNA expert Kobilinksy made his comment, above, just last week. So apparently there are still problems with the reliability of the technology.
     
  8. Ivy

    Ivy Inactive

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    Shylock...thanks! That's good, sound information. It supports what an ABC online article (no longer available) said about PCR amplification. The article stated that according to CellMark, when the DNA being tested is old, degraded, or damaged, the imperfect DNA is amplified too. The imperfect DNA, or non-matching DNA, often produces extra markers (stutter bands, also called shadow bands) and gives a false impression that another person's DNA is mixed in with the sample.
     
  9. FULTON

    FULTON New Member

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    It appears from these posts about DNA that some DNA code not matching anyone on the planet may result from these tests.This sounds almost like a "checkmate" spin by the defense team.We now have DNA who's we will never know because he only exists in the laboratory.
     
  10. Shylock

    Shylock Former Member

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    Quote: "Warm moist conditions may accelerate DNA degradation...in a relatively short period of time."

    Warm and moist, like in a person's crotch after they've urinated in their panties? (The autopsy documents that the panties are "urine stained".)
     
  11. Ivy

    Ivy Inactive

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    Fulton...BINGO!

    A continuous no-match on the sample will give the Ramseys and Wood free rein to continue filing lawsuit after lawsuit, ad infinitum.
     
  12. Shylock

    Shylock Former Member

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    Actually, "amplification techniques" are not even relevant to this case. They have always been able to amplify DNA by millions of times. The amplification of contamination is NOT a desired effect.

    What would be important to this case since that article was written would be recently developed "filtering techniques"--which would filter out contamination. But then, if you filter the contamination out of the DNA samples in this case, all that remains is Jonbenet's DNA. There is no second source, either under JonBenet's fingernails or in her panties, that is viable enough to amplify to a complete DNA profile.
     
  13. BlueCrab

    BlueCrab New Member

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    I don't think it's the DNA that's allowing the string of lawsuits involving Burke to be settled -- it's the fact, IMO, that Burke is protected by the court protective order that has been slapped on the case.

    The court will not allow any of these lawsuits to go to trial because it would involve discovery that would violate Colorado law protecting the privacy and identity of juvenile offenders. The New York Post went as far as it could and anyone could to prove Burke's involvement, but in the end had to settle. No court is allowed to violate another court's protective order.

    IMO the case was solved by the GJ and is over. I just hope no adult involved in the killing is walking.

    Just my opinion.

    BlueCrab
     
  14. sissi

    sissi Former Member

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    This information may apply to the original dna,however what is there to indicate
    these issues apply to the newest sample sent? Is it just conjecture on the part of
    those that really don't want there to be viable new evidence?
    ?IMO
     
  15. Ivy

    Ivy Inactive

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    sissi, it's my understanding that the "newest sample" is merely an amplification of the original.
     
  16. Shylock

    Shylock Former Member

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    This information applies to DNA TECHNOLOGY, past, present, and future. Crime scene contamination will be the same problem in the year 3000 as it was in 1996. (Probably worse, since the world isn't getting any cleaner...)
     
  17. Barbara

    Barbara New Member

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    We are getting bits and pieces of who has been tested. Noticeably absent from the list are Burke Ramsey and ........Daddy Paugh

    He is a strange one and we hear nothing about him, not even from the RST. It's as if he doesn't even exist.

    He is #2 on my list of suspicious characters.

    #1 is Susan Stine (but not for DNA reasons)

    Actually, nobody is on my list for DNA reasons, as I think this will be a non issue: We have 2 scenarios

    1. The DNA will never match anyone
    2. If it is eventually shown that the DNA DOES come from a Ramsey, then suddenly the whole transfer theory will become valid for everyone, just like the fiber evidence of Patsy's jacket. Now it has become acceptable that her fibers are IN THE GARROTE because she lived there.

    :croc: :croc: :croc:
     
  18. Ivy

    Ivy Inactive

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    quote (Barbara): Now it has become acceptable that her [Patsy's] fibers are IN THE GARROTE because she lived there.

    Me: Isn't it amazing how R supporters, when confronted with evidence that might implicate a Ramsey, are able rationalize like that?

    I think you're right that if the DNA is shown to have come from a Ramsey, the RST will spin it to suit their agenda. The mystery DNA scenario is a win-win opportunity for the Rs and Lin Wood.
     
  19. Britt

    Britt New Member

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    Right, Ivy. That's my understanding, too.

    Sissi... conjecture is all there is. There is NO official information, only the word of the lawyer for the prime suspects, who says that earlier test results were not of high enough quality to submit to the database, until a "new profile was worked up." What would you say that means?
     
  20. Britt

    Britt New Member

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    lol... ain't that the truth!

    And, oh yeah, what about Grandpa Paugh anyway? He's not a "Remsey," now is he?
     
  21. sissi

    sissi Former Member

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