I'm a firm believer that representation of all kinds is important--even, if not especially, in role play. And it's definitely easier to write into some RPs compared to others, but I believe it's doable no matter the RP with enough determination.The most common ones I see played out in role plays are amputees and the blind.

Unfortunately, it rarely works. Not usually at the fault of the RP itself, however, but at the fault of the player. If you can't empathize with your character well enough, you're not going to be able to play him effectively. If you have it in your head that the disabled can't contribute, you're not going to have much to contribute within the RP either.