Based on the article, we don't even fully understand the mechanism behind the disease. Hard to do gene therapy when you aren't sure what genes are to blame.
There could be epigenetic or environmental factors to blame for a disease.
But even so, assuming this is a genetic issue, proposing gene therapy in this case is putting the cart before the horse. It's like if you had a memory leak or segfault in a 3.4 billion line codebase, but the issue was only reported a few times (out of 7+ billion active users) and you can't replicate it. Obviously, a patch for this issue would be nice, but first you need to find out what's causing the issue.