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Comment by jjcon | Hacker News Reader

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.

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

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.

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