I have traditionally said that good design is also design for accessibility. And there are many cases where mobiles are used by anyone in an environment where some input our output may be obscured, so every design should assume accessibility.
But... that's not always 100% true, and if you do have a special population, there are special cases to consider.
I'll eventually put some effort into specific guidelines, or at least a series of links. Here's one to start with: