Iverson's Disease was a chronic and progressive muscular disorder that affected Humans. It caused fatal degeneration of motor skills, but did not impair mental faculties. There was no known cure and no known case of remission.
In 2359, Admiral Mark Jameson was diagnosed with this illness. Jameson attempted to alleviate the symptoms by using an alien drug from Cerberus II to reverse the aging process. While this appeared successful, Jameson's overuse of the drug eventually killed him. (TNG: "Too Short a Season")