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Comment by jjcon | Hacker News Reader

> chances are good that one of the first things you did as a baby was give a DNA sample to the government.

This seems pretty disingenuous - yes you gave a blood sample (which has DNA in it) but no DNA genome sequencing is taking place - they simply check it for a series of disorders to make sure a baby is healthy and yes gather aggregate data on prevalence of disorders at the population level.

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But do they keep it somewhere for further analysis later (very useful medically if you want to backtest things) or do they programmatically destroy it?

In nearly every western country (EU countries, Canada, Australia, New Zealand etc) the samples are securely stored indefinitely - in the US it depends on the state but many do keep the samples there as well. That does not mean they are readily accessible- there have been cases of misuse but it is extremely rare.

From a DNA perspective one can only use the Guthrie test samples for about a decade after collection so yes, in a worst case abuse scenario we have cards that could be mined for DNA across a bunch of <10 year olds.

> From a DNA perspective one can only use the Guthrie test samples for about a decade after collection

Why is that? Is it because of sample degradation of some kind?

Yes - blood must be kept at very specific temperatures and conditions if you want to preserve its usefulness in DNA sequencing - most of these are dried blood cards without strong controls which makes them not particularly useful for good DNA data.

Scientists have extracted usable DNA from from 7000 year old corpses. I imagine the technology exists for a decades old blood sample if it’s stored at least somewhat properly.

Yes that is very true - There is however quite a bit of difference between a full corpse that is mildly preserved and a dried fleck of blood - a big difference too between a stored fluid blood sample and these pinprick dried sample.

It's probably prohibitively expensive at the moment.

Would you prefer it said "blood sample that can later be mined for DNA"? No one has a problem with the initial health screen. The problem is that they keep it around later in a form that can be used like this.

Maybe - the blood isn’t collected for DNA sequencing so they aren’t DNA samples. Furthermore DNA could only be realistically extracted from them for limited time (about a decade). If you want to view it as a DNA bank, it’s a pretty terrible and temporary one.

Would love to see a citation for your second claim.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3883779/

“We and others recently have shown that DNA extracted from Guthrie cards (up to a decade old) or blood spots can be used to perform whole-genome methylation analysis”

Is a whole geneome methylation analysis needed for criminal prosecution? Seems like the bar would be lower there. You don't need to know the whole sequence in order. You're just comparing it against a sample to see if there are enough matches to establish a linkage.

I'm no expert though. Hopefully others can weigh in.

I don’t know why they write that, but one of the papers they quote for that claim reported success with samples up to 19 years old and in turn cites a paper that reported “genotyping whole-genome-amplified DNA” from up to 25 year old blood spots. I don’t know what this means exactly, it definitely isn’t the methylenation thing, but I think it’s a good indication that blood much older than a decade is viable. Both of these papers also report no differences in results between older and younger samples, only between different extraction methods and amounts.

> 19 years old and in turn cites a paper that reported “genotyping whole-genome-amplified DNA” from up to 25 year old blood spots

You are notably omitting that those specific samples were kept at -20° C. I don’t know any country that does that for their Guthrie samples.

I did actually miss that. But my point is that none of the papers established a limit at 10 years and it’s not clear at all how the authors came up with that number.

The newborn blood is often sequenced, and often sold or provided to third parties in a loosely anonymized fashion.

They absolutely use these in court (incl. criminal prosecution) in New Zealand and have since at least 2000:

https://www.nzherald.co.nz/nz/lawyer-challenges-courts-right...

and

https://www.stuff.co.nz/national/crime/97840280/parents-upse...

You can fill out a form and demand they return the samples to you.

Even if you can trust the government today, there is no guarantee they can be trusted tomorrow. cf. the abortion stuff in America.

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