A savant, by definition, is somebody who has a disability and, along with that disability, has some remarkable ability. Prodigies and geniuses have the remarkable abilities that the savant shows, but they do not have a disability. So, by definition, a savant includes someone with a disability, and a prodigy or genius are people who have these remarkable skills but they do not have a disability.
Not everyone who has a savant skill I would equate with a genius.
To some extent, we all have quirks or idiosyncrasies, and some geniuses, because of how bright they are and how focused they are, may have liberal eccentricities, but they're not at a disabling level.
There is such a thing as genius, and these are people who do not have a formal disability, DSM-IV-type. They may have liberal eccentricities or quirks in their personality, but they don't rise to the level of a disability.
