Still that's the best we can do atm. Still all those anti-GM people actively hurt our chances to get real treatments soon.
I'm sure that it's because of the big pharma conspiracy which tries to keep that technology secret so that they can make more money.
/s
If you're susceptible, you might get it, might not; if you aren't, you aren't. Guess what, no point of carrying bad genes around.
(I am a diabetic who does genetics)
For the time being one of the most effective means of studying a disease is to sequence a pedigree of individuals some of whom have the disease and analyze the inheritance patterns until you narrow it down to the point you can be sure.
You can also do studies where you just sequence a ton of people with and without the disease but those can be more problematic statistically because of the number of possible variants.
"Above all, do no harm" makes for a very conservative approach of being really sure before risking actual action.