Bit of a shot in the dark on my part, but here goes: My daughter stopped walking about the time she was six. The disease began around the age of four. She's in a wheelchair full time. MRIs, EMGs, etc. are 'normal'; one doc said he could show her file to his students and they'd say she's 'normal'. We've eliminated ALS, CMT, CP, etc. To date we've stumped National Children's, Hopkins, USC, UCLA, St. Louis, and two separate teams at NIH as to what the heck happened and can it be fixed. NIH's best guess is that there's something in her exome - exactly what, they don't know.
So, I'm throwing an interesting case onto the table. Can't offer much more than that; and bragging rights at the bar.
Let me know what you need in the way of data and I'll see what I can get from NIH.