Help! Somebody has my DNA...

[tigger1]

...well, they will tomorrow. The occasion? I'll be giving blood. Now, according to last months "The Donor" mag' from the national blood service, some of my DNA might sneak it's way into their blood via (one of, I can't honestly remember, but anyone with a decent recall of GCSE biology will put me right!) red or white blood cells.

Now, whilst I don't really mind this, the DNA will be gone in a week or two, it does beg an important question (to me, anyway), what if this person were to kill somebody a couple of days after receiving "my" blood? I know the chance of my DNA being the one detected there is slim, and also the chances of me volunteering my DNA to the police, but it does seem to me that the chance of DNA evidence being wrong isn't the 0.000000000000001% (urmm...guessing at the fraction!) that the powers that be would have us believe.

[pdV6]

I suspect that if they're in a position to need your blood, they're probably not really in a position to be raiding the post office with a stocking over their head?

[dcw@pr]

red blood cells make up the huge majority of your blood (96%) and do not have nuclei, and therefore do not contain your DNA. white blood cells make up 3%, and do contain DNA. I do not know specifically, but I would guess that your white blood cells are either removed from the blood before transfusion, or they will be taken care of very quickly by the recipient's own white blood cells, otherwise you would have a bit of a reaction to them, and I have never heard of that happening.

[tigger1]

pdV6 said:

I suspect that if they're in a position to need your blood, they're probably not really in a position to be raiding the post office with a stocking over their head?

Having spent 3 years working in a hospital, 18 months of which was in T&O, I suspect you are wrong...I think many of the BiB on here will be able to tell tales of the scum they've had to babysit sat in hospital wards / A+E.

Anyway, it was all hypothetical, it's very unlikely!

[lunarscope]

Don't worry, DNA evidence cannot be used legally to identify absolutely an individual person. It can only be used to discount the identify of someone.
However, the Judiciary don't seem to understand this point (and are easily baffled by science) and still think that DNA evidence = proof.

[MilnerR]

As already mentioned, bllod is mainly made up of red blood cells which will only contain mitochondrial DNA and not nuclear DNA. Blood is usually stored as packed red blood cells (i.e. depleted plasma) and the leukocytes (type of white blood cell) are filtered prior to transfusion. The situation you refer to is very unlikely if not impossible, don't get too paranoid

[tigger1]

MilnerR said:

The situation you refer to is very unlikely if not impossible, don't get too paranoid

Whilst I would have agreed with you up until a couple of weeks back, it was the National Blood Servise themselves who said it can happen, and that the DNA could in theory remain for a week or two.

That's very interesting that DNA can't be used to prove, only to disprove...I know law students now have to learn about Bayesian statistics ("what is the probability of event B[prob(B), knowing prob(A) and prob (A|B)", that kind of thing, but stst's are much abused throughout the media and judiciary...(and the scamera's)...which has led DNA evidence to be taken as 100% irrefutable fact. Scary.

[tigger1]

Found the article eventually...

[quote="The Donor", summer 2006]DNA detection?

www.blood.co.uk/pdfdocs/donor_sum2006.pdf

I’m a regular donor and have now donated 45 times. Recently I have started wondering about DNA. We hear lots of news stories about crimes being successfully solved using DNA analysis. What I want to know is, when someone receives my blood, do they have traces of my DNA and if so for how long? As we could all be on national databases in the not too distant future, it would be good to have some reassurances.
GILLIAN PERRY BY EMAIL

EDITOR’S RESPONSE: Neither red blood cells nor platelets have
nuclei, so they will have no DNA. There is a possibility that
transfused blood will contain some white blood cells but these cells die within a few weeks of the transfusion.[/quote]

[busa_rush]

tigger1 said:

pdV6 said:

I suspect that if they're in a position to need your blood, they're probably not really in a position to be raiding the post office with a stocking over their head?

Having spent 3 years working in a hospital, 18 months of which was in T&O, I suspect you are wrong...I think many of the BiB on here will be able to tell tales of the scum they've had to babysit sat in hospital wards / A+E.

Anyway, it was all hypothetical, it's very unlikely!

You're thinking of a very small number of cases. My Father wouldn't be alive if it wasn't for the generosity and kindness shown by the 1000's of blood doners in the UK. When he had his transfusions he was struggling to stand up out of a chair so committing any kind of crime was impossible.

[MilnerR]

If you have a blood transfusion then your own white blood cells will massively outnumber the relatively few found in filtered transfusion blood. Therefore the vast majority of DNA present in any sample will be yours and not the donors. PCR amplifies DNA by the proportion that is in the original sample, therefore if the donors DNA represents 5% of the sample it will still only represent 5% in the amplified sample. When the sample is then processed for RFLP I doubt the donor signal will be detected over the overwhelming host DNA signal.......

Trust me, I mess about with this sort of stuff for a living

[tigger1]

I'm not concerned, just throwing in an idea about weight of DNA evidence - I don't think it's all its cracked up to be.

As for donor's, I gave a pint (ish) today, that's my 14th now I think...and I won't stop until they won't let me...I know first hand how important it is that there are ample stocks.

[Stubby Pete]

As long as you can prove that you gave blood, a half decent brief will be able to argue any case brought against you.

Although, to put two and two together your DNA would have to be on file, and it probably isn't (unless you are a registered sex offender or convicted criminal).

[Dwight Vandriver]

THREAD HI-JACK BUT RELATED.

Any of you see the report that a road rager had spat at the object of his red mist.
Police dealt and recovered spittle from injured person which contained the DNA of the offender who just happened to have past form and his DNA on record. Result.

Moral: Goad the burghers and get themn to spit at you?

dvd

[tigger1]

Stubby Pete said:

Although, to put two and two together your DNA would have to be on file, and it probably isn't (unless you are a registered sex offender or convicted criminal).

Or any of the number of people who have been innocent of anything but asked to "voluntarily" give a sample...or, on the off chance that such a hair brained idea actually goes through, if you have a biometric ID card, which would possibly mean all of us handing over DNA.


DVD - in Nottingham I believe many bus drivers now have DNA testing kits so that if anyone spits at them they can take a quick swab.