It really depends. I wouldn't feel physically attracted to someone in a wheel chair for example and that's the basis on which I decide if I see someone as a potential date and then flirt with them etc
But if we became friends and then feelings developed, I don't see why not, it just wouldn't be the same way into a relationship.
If it were something more hidden, then I still don't see why not.
The only problem would be if they required help from me constantly and were dependant on me for things a lot. I wouldn't want to enter into a relationship like that seeing as a) I am not self-confident enough to shrug away doubts that they just want me for the help and b) I'm still young and don't want to have to be that reliable.
Of course, if someone I'm already in a relationship with became disabled and more dependant, that'd be different as the basis was already there before.