I can't say I'd be surprised...
On a serious note, controlling a disease with medication is not actually curing a disease. It is, as you suggest, controlling/halting the progress and minimizing or eradicating symptoms to allow a person to live comfortably.
But you do not actually cure the disease. They still have it. And they still have the genes that code for that diseased state. In other words, if you stop giving them the drug, the disease will reassert itself and/or kill them. Diabetics live mostly comfortably because of administering the drug insulin, but they still have the disease.
If you can give them a drug that re-writes or edits those responsible genes (ala gene therapy), then you can cure the disease. Or if you can kill the diseased cells (as in cancer therapy), then the person no longer has the disease and you have cured them, but the problematic genes that gave them a propensity toward contracting cancer again are still present and active, so they can get it again. Cancer is actually a bad analogy for this one because it has so many different factors that play into it, but in the sense you can kill the diseased cells while the patient still maintains a genetic predisposition towards that certain cancer type, the analogy works decently.
If you are able to edit the genes before birth however, then the "healthy" version of the genes is theoretically passed down to every cell line as the zygote develops, thus permanently curing the person so they never need medication for that particular disease (cystic fibrosis comes to mind, since it kills people and medication can at best slow it down).
Obviously however, the ethics of doing this....man where do you start? This IS eugenics on the molecular level. Not to mention mass unintended consequences potential.