[McKayDavis]

> Unless I am unaware of something, CRISPR is not yet ready for medical usage.

CRISPR has been used successfully to treat Sickle Cell Anemia in at least one patient. [1]

You're spot on though that there are many obstacles to overcome (such as off target effects). CRISPR-Cas is not the answer, but rather just one more tool in the gene editing toolbox, albeit a very powerful one.

https://www.npr.org/sections/health-shots/2020/06/23/8775436...

[ImaCake]

Yes, plenty of examples of gene editing in sick adult humans in the literature :) We have done the same with older techniques using zinc finger nucleases (same mechanism, but much more difficult to "program) and also infecting cells with lentivirus (modified HIV) to insert some useful genes. The problem is that none of these has been good enough to implement generally to save lives. Although, the lentivirus infection of T4 killer cells to fight late stage cancers seems to have promise.