As someone else actually pointed out someone with Autism could be just as easily represented with high intelligence and low wisdom & charisma. This innately causes drama; but it would be almost definitionally offensive.

Just the imagine DM saying: "You can try to seduce the guard, but remember you have a -2 to all charisma rolls because you're autistic. ... Oh, looks like you rolled a 1. You walk up to the guard, do some weird retard thing with your hands and say, 'GNNEEAGHH KHNNAAFFF'. He is disturbed and alarmed. Roll for initiative."

Or, for your wheel chair example: "The enemy mage casts a magic spell to the ground. It makes the surface around you slippery. You begin slowly rolling backwards away from the fight. You will now roll backwards 5 feet at the beginning of every turn. The Orc laughs at you and calls you a "stupid wheel slag".