biology epq help!Watch
The way I initially went about mine was by picking a few things in different categories (mine was on transition healthcare) so I went for children with long-term head injuries, children with long-term genetic illnesses and children with long-term congenital defects and disorders. You could possibly do the same where you pick out a couple of common untreatable disorders that are very different from each other and focus on those.
I think it's fair to say that you should be willing to change to title. I struggled for way too long with mine before admitting defeat and changing my title only slightly, to accommodate available research and I then powered through and found myself writing nearly 3000 words over the requirements. Right now your idea seems solid, and it possibly is but the EPQ is a very fluid thing. The log you have to write up alongside your EPQ is there purely to record your plans, then everything you are successful in or fail in and have to change, and any reflections you make about your progress.
The only other thing I'd say is that your title sounds like it would be very difficult to get primary research. I had great difficulty in speaking to children in my areas due to confidentiality and child protection on data etc - my friend had to create a private online survey which she then trawled through literally hundreds of experts to send the link out only to receive less then 5 replies.
Sorry for dragging on, hope this helps