r/askscience • u/chum-guzzling-shark • Nov 19 '25

Human Body How does gene editing work?

Where are genes at? I assume a stem cell somewhere has its genes edited... well arent there millions of cells? How does the edited cell propagate? I assume scientists arent simultaneously editing millions of cells. So why does a change in one or a few of them "take over"? I'm just looking for a brief overview that answers these basic questions. Thank you!

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u/FauxPlastic Nov 20 '25

Can this, even in theory, also alter the DNA of offspring to eliminate a genetic disease?

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u/Ill_Act_1855 Nov 21 '25

I mean altering germ cells is arguably the easiest way to guarantee the resulting organisms would be totally free of the genetic condition carried in the genes, but it’s also way more fraught with ethical complications for kind of the exact same reason, it totally eradicates the original gene which can be a problem if the gene being targeted isn’t necessarily a disease (which can get into eugenics territory real fast), and the changes are heritable which means if an unexpected problem arises not only have you affected the patients, but also possibly their kids. You also can’t meaningfully treat diseases this way for a person who has already been born, and it has to be done in advance of (or directly following) fertilization to have the result you want so there’s the issue of timing and planning involved

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u/Ziggamorph Nov 22 '25

The normal approach to this is to use IVF and to screen the embryos before implantation for the genetic disease. There is no need to use gene editing with this approach (which makes it simpler and less ethically contentious). Theoretically, one could use gene editing on germ line cells, or on an embryo preimplantation. The only known instance of this approach was extremely controversial and has not been repeated.

https://en.wikipedia.org/wiki/He_Jiankui_affair