system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how would gene editing work on a person that is already born? Wouldn’t the DNA in every cell have to be altered individually for it to be effective?
gpt
Depends. If you want to edit a gene that is only active in liver cells, then who cares what gene your skin cells have, you only need to edit liver cells.

But yeah, the more widely used the gene in question is, the harder it is to get to it everywhere. That is one of the main reasons gene therapy still is as limited as it is. It is being worked on though, but will probably never work like in Hollywood movies.