I know you put an asterisk, but to make it clear: these locations are very far from random. They're the most informative positions, which is why we check them.
replyWell, they're what 23andMe thinks are most informative, for the things they think their customers care about. Or thought; for compatibility reasons they can't change their SNP panels very often or too much.
replyAnd the interesting positions are still reasonably randomly distributed by nature :)
I don't do SNP design but I don't think 23andMe made their own chips at first (if they have ever). SNPs are chosen based on being informative for population discrimination, with traits being overlaid afterwards
replyI could be wrong, but I do believe they get to choose. What I do know is that none of the big testing companies test exactly the same SNPs, there is some overlap but every test is different. They also change their SNP sets from time to time, 23andMe has changed at least 5 times, and interestingly, their current test isn't the biggest (it tests fewer SNPs than some of their earlier ones).
replywell SNPs aren't useful for drug development, commercialization, medicine, etc. you want whole genome or whole exome sequencing for stuff that is future-looking. they use a process for the present day (quickly becoming the past) of okayish drugs instead of sequencing for a future of cures.
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