It was posed to be a revolution when I started my career, some 30 or so years ago. The pace is glacial. There is no systematic way to deal with this; nearly every disease has its own details, and individuals differ so many treatments have to be personalized. Many of the changes we make, we don't really know how or why they work.
I've left human biology and returned to model organisms because the experiments allow for much less ambiguity.
Yeah it seems like that was the norm in the past, but it’s looking like CRISPR and it’s successors are shaped to change that. As long as the set of relevant genes is small, and in a small enough number of cells it should be possible to scale up. Genetic degenerative diseases of the eye, sickle cell, and similar show a lot of promise.
I've left human biology and returned to model organisms because the experiments allow for much less ambiguity.