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Comment by notQuiteEither | Hacker News Reader

As someone in the field, I can say with certainty to expect FDA approved liquid biopsy tests (for somatic variants) to start appearing on market in the next year, if not sooner.

I'll also point out that detecting germline variants (which is what Invitae is doing) is considerably easier than somatic variants, which is what tests ala Grail and PGDx do. Of course this doesn't discount the work of Invitae, absolutely sound tech behind it.

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Yeah I'm willing to bet there are more than one liquid biopsy tests submitted and likely to get approved.

I worked at PGDx for ~5 years and wrote an appreciable chunk of their bioinformatics pipeline, though I moved on to a different industry back in 2020 and am now out of date by that much. Though if you had asked me then, I would have bet that the first liquid biopsy test would be out by now; when I left was a short while after they had the first solid tumor somatic test FDA-approved.

Grails test isn't for somatic mutations but cancer specific DNA methylation patterns. DNA methylation is slightly more challenging to work with due to how the methylation is identified from sequencing data. There's a chemical of enzymatic step to convert unmethylated bases to another base. In humans it's usually unmethylated cytosines to thymines. The analysis is also more complicated but mostly standard now. Nonetheless, DNA methylation has proven to be very useful for liquid biopsies.

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