I worked with a woman with Friedreich's Ataxia for a couple of years. Her mind was fine, but she had over twenty or so years gotten to the point where she was living in a powered three-wheel chair. Unfortunately, she also thought she could do more than she could and would sometimes over-reach for something, the chair would tip, and she'd lay under it until someone came by (she wouldn't ask for help). She had a wonderful husband; once her chair shorted out and caught fire, he suffered third-degree burns on his hands lifting her out of danger.

FA manifests itself in the young and causes progressive degeneration -- twenty years before I knew her the woman above was completely mobile, although she walked with a slight "stutter." It's also genetic -- her brother also had it.