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jrm5100

14 karma · joined September 27, 2016

McGuigan.dev
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jrm5100··on Accused murderer wins right to check source code of DNA testing kit
Issues with source code access aside, your description is mostly wrong. These programs take a DNA profile as input- it's just that the DNA profile is mixed (i.e. from multiple people). It reporting no DNA would be nonsensical. Figuring out exactly how many people are in a mixture isn't quite nailed down statistically (last I knew of), but it's usually pretty clear for up to 4 or so people.

Yes, you could run different models and get different probabilities. For example, the likelihood that the sample is a mixture of the suspect, the victim, and some unknown person vs victim and two unknown people compared to saying the victim isn't in the sample. However, the specification of those models is part of the trial process.

And the output probabilities (at least when being used to determine guilt) are usually quite high, orders of magnitude higher than 90% or even 99.99%.

My point is that the science behind these calculations is well developed- validation studies get published all the time. Whether or not the specific software has errors (or isn't coded exactly as modeled) is an entirely different matter, but it still isn't all that likely. All of these cases rely on expert witnesses anyway- it's not the prosecutor pressing some buttons and printing a report.

There is far more concerning quackery that gets used in forensics- bite marks, hair matching, etc.

jrm5100··on HyperFoods: Machine intelligent mapping of cancer-beating molecules in foods
As far as I'm aware pathogens in meat aren't the main issue- it's the compounds formed when the meat is cooked.

https://www.cancer.gov/about-cancer/causes-prevention/risk/d...

Fish cooked at high temperatures is also not good.

jrm5100··on Amazon raises minimum wage to $15 for all US employees
> If so, why didn’t the employees change jobs?

Monosopy.

jrm5100··on Nanopore MinION – $1k solid-state DNA sequencers
The forensic field moves very slowly in adopting new technology since they have to do a lot of re-validation every time anything changes.

This idea already here, but with technology based on older/simpler methods. One example is Intigenx: https://integenx.com/rapidhit-system/

The FBI has plans for implementing them: https://www.fbi.gov/news/testimony/fbis-plans-for-the-use-of.... The laws just need to catch up (or prevent it).

jrm5100··on Ask HN: What projects are 20 years ahead of their time?
It may be millions of units by now- it was 1M about 2 years ago (https://www.genomeweb.com/microarrays-multiplexing/1m-custom...).

Minor nitpicking: the 23andMe kits use microarrays for genotyping, not DNA sequencing. It's an older and more limited technology but it is much cheaper than sequencing.

jrm5100··on Supreme Court sets higher bar for education of students with disabilities
To add to your points, a very important consideration is that charter schools can game the metrics by forcing out students who aren't performing well, while public schools can't turn anyone away. This may be why they seem to improve test scores without making any actual difference [1].

Public schools can use charters to game metrics themselves too [2].

[1] http://www.nber.org/papers/w22502

[2] https://www.propublica.org/article/alternative-education-usi...

jrm5100··on Color Genomics raises $45M to provide genetic tests that detect cancer risk
The Sanger/TCGA (The Cancer Genome Atlas) stuff seems to be specific to microarray data which is different (older, more expensive) than the newer high-throughput data.

The figure you linked is a good explanation. The split read method is helpful for finding the edges of the CNV, while the number of reads (relative to other regions that were tested) can give an idea of the number of copies. The problem is that these methods all have their own unique biases/noise that makes it non-trivial to figure out the absolute copy number change.

Ideally they would find a similar CNV that has some clinical association.

The DGV has a lot of reference CNVs. Here are some in BRCA1: http://dgv.tcag.ca/gb2/gbrowse/dgv2_hg19/?name=id:3087443;db...

jrm5100··on Color Genomics raises $45M to provide genetic tests that detect cancer risk
plus a special sauce for counting the number of specific bp repeats, due to in-del events, this is not something I am not too familiar, but presumably the number of a specific k-mer repeats you have in these genes of interest might correlate to a specific type of cancer? (would love to hear someone who is an expert in this field their opinion).

"Copy number variant" refers to larger deletions and duplications that can occur in the genome. There isn't some specific cutoff for size, but some examples in these kinds of genes would be an entire exon or gene. There are countless studies that find correlations between specific variants or CNVs and risk of cancers.

Standard variant detection is pretty straightforward. CNVs are harder because they are longer (several hundred to several thousand base pairs) than the raw data (150 to 250 bp for Illumina)- you don't get single reads that span the entire variant. You have to normalize then look for differences in coverage, or look for split reads (where the read is aligned on the border of one of these CNVs).

This kind of funding baffles me because they don't seem to be proposing anything new at all (maybe slightly better CNV detection?) and there are already lots of labs/companies doing this kind of testing. Maybe they are working on being very efficient to offer a better price.