DNA Extraction From Fingerprints

Myriad writes "A Canadian scientist has developed a new way of gathering DNA evidence for analysis using fingerprints. The new test can extract DNA in 15 minutes - even from a print stored for many years and in varying conditions. The patented extraction technique consistently produces ~10 nanograms of DNA. Analysis generally requires 5-10 nanograms, although it is possible with as little as 0.1 nanogram."

Comments

This is good...

[PakProtector]

...as I think it will seriously make finding the guilty easier, and seperating the innocent from the guilty. If I'm not mistaken, it currently requires a judge's order in the united states to collect a DNA sample. Now all you have to do is dust something touched by the suspect to get a DNA sample.

Court-admissible

[joelt49]

You always have the problem of getting it admitted in a US court. Expect big battles over this. For example, if the judge isn't the most tech-savvy judge around, someone could bullshit him/her into believing that the DNA samples are unreliable. Also, you have the BigBrother concern. However, fingerprints are already considered uniquely identifying. The only added problem w/ getting DNA from fingerprints is technology that is still years away, if it even comes to the market -- predicting people's characteristics/future death from DNA. However, the only reason to get the DNA from the fingerprint and not from the sweat that the person left, or the hairs that the person left, etc., is because of the storage factor. So, while people worry about their DNA being extracted from a fingerprint, they should be more worried about all the hair follicles and skin cells they are leaving behind that also give away their DNA.

Re:Court-admissible

[cybercyph]

finger prints are uniquely identifying, but often times they themselve's are unidentifiable...if they are smuged, or incomplete. DNA extracted from a smudged fingerprint could be used to identify the print's owner

Re:Court-admissible

[bmajik]

you know, i want really badly to agree with you. What everyone wants is some black and white way to know beyond the shadow of a doubt that its time to put away some repulsive violent criminal. Who wouldn't be 100% in favor of putting away rapists every time ?

When i first heard about people protesting DNA evience i was really outraged because it seemed to easy, so black and white, to get convictions that were difficult or impossible otherwise.

Upon reflection, im greatly worried. If faith in DNA evidence is unquestioning then i worry that any way it is used at all becomes an upen and shut conviction.

Consider the scenario that my friend hands me a gun, then 2 hours later uses it in a glove job. My finger prints are on the gun. My DNA matches those in the prints _exactly_.

Here's what the jury will hear:
"The irrefutable DNA evidence links the defendant with the murder weapon."

a more realistic and frightening scenario, perhaps, was used in the mid 90s hollywood production, "The Crush". The teenage girl with an unhealthy fixation on the man renting the room from her parents fishes a used condom out of the trash and manages to insert the expelled semen into herself. She fabricates a rape story and the police have evidence of semen inside her body that is of course a perfect DNA match...

reliance upon technology to determine what did or didn't happen will continue to increase. the risk is that the application of this information will be misused. I do not trust a jury to have healthy skepticism of the CIRCUMSTANCES that produce a DNA sample in light of the fact that a DNA _match_ is 100% irrefutable identification and makes the job of being a good juror so ... easy ..

think about where you are leaving your dna and how you might be implicated by it..

How does this help?

[groove10]

If you already have the fingerprint, why do you need the DNA? Most criminals (or at least those arrested and brought to jail) are processed via fingerprints and that is what's stored.

Does this indicate a move toward DNA databases instead of fingerprint ones?

Will this save any time or effort on the part of law enforcement agencies?

Will newborns have their DNA sampled shortly after birth?

/me puts on his tin foil gloves

Not Good

[phatcat625]

This could possibly lead to more false positives than now. Say you try to help a stab victim. If you touch the person your DNA will be on them and it's possible that you could be implicated for the murder.

DNA not used for proving guilt

[nsideops]

I'm certanly no expert, but I understand it's extreamly more difficult to prove guilt based on DNA evidence. It's more often used to prove innocence or provide that shadow of a doubt. This technology could greatly help in lowering the chance of someone being falsely prosocuted for a crime.

Re:True, but.... not

[Zemran]

Large databases are being built up of fingerprint data and now DNA data. The acuracy of this data is at best questionable. Fingerprints are measured at 16 points. From this you do not get 16^16.
I think that if you measured fingerprints to an infinite acuracy you may find the theoretical infinate number of fingerprints required to sustain the myth that no 2 fingerprints are the same but here in the real world we measure a finite number of points and therefore have a finite number of prints and as the database reaches that number there must be mistakes.
The mistakes are already happening with DNA and because this evidence is perported assumed to be infallible innocent people are being arrested.
If this evidence was only used to support other evidence I would see it as a good thing but when it is used as the only evidence then it is very bad.
I think that in the future this DNA witch hunt will be seen for what it is but for now innocent people will be caught up with the guilty.

Proof, Sampling Errors, and Racial Differences

[nhaze]

DNA extracted from the region of a fingerprint does not prove that the DNA came from the fingerprint.
Residual DNA coats every surface and depending on the environmental conditions, whether it is inside or outside exposed to the sun, many other sequences will be present.
Current sampling and extraction techniques can not avoid this contamination and if your favorite hangout turns out to be a murder scene, well you are in trouble. While control samples taken at the scene in areas where 'no fingerprints' occur can be taken to test background DNA, it certainly is not foolproof.
Additionally, races and skin types slough skin at different rates and have significant oil-content differences, so there will also likely be a discrepancy in who gets caught. tough luck.

Numbers (10 ng) don't make sense to me

[a-aiyar]

I have a hard time believing that they can extract 10 ng of DNA from a fingerprint. A diploid human cell as 6x10e9 bp of DNA. One bp is 660 daltons. Calculating backward, 6x10e9 bp works out to being 6.6 pg of DNA.

So for them to extract 5-10 ng of DNA from a fingerprint, a fingerprint needs to contain between 1000 - 2000 cells. I work with epithelial cells, and a 1000 - 2000 cells is a fairly large patch of cells.

So either they mean that they get 10 ng of PCR amplified DNA (which is possible), but then is hardly representative of the entire genome, or they are using fingerprints from people who are really shedding skin!

Re:True, but.... not

[Daniel Dvorkin]

Slow down, cowboy. I don't think the poster was questioning the accuracy of the DNA analysis techniques themselves, but rather the degree to which the techniques uniquely identify an individual.

You say:

The chances of two people having exactly the same combination of restriction-snipped fragments is so so so so *so* small it is difficult to express in numbers

This is only true if you get a sufficiently large number of fragments. If you're analyzing someone's entire genome, of course you're right -- the only possible way to get an identical "DNA fingerprint" is on identical twins. But in fact the number of fragments analyzed is fairly small, in the thousands; which means it's possible to get the same analysis out of several million unrelated people, and a much smaller number of closely related people. Considering how many crimes are committed by one family member against another, this is a real concern.

I'm all for DNA analysis as a forensic tool, since it's currently the most accurate tool we have for placing a suspect at the scene of a crime. But it's a long way from perfect. Presumably, as the technology improves and it becomes practical to analyze larger sequences faster, it will get better.