Sean Scoggins asked:

>Don, is gluten found outside of grains?

No.

> Could you (or anyone) summarize
>briefly the most potent sources of gluten?

From a Martin Kagnoff speech:

When we talk about a gluten-free diet, what we are really talking
about are these alcohol-soluble proteins, which are named as follows:

     Grain          Proteins
     -----          --------
     wheat          gliadins
     barley         hordeins
     rye            secalins
     oats           avenins

Note that we are not talking about a single protein. A variety of
wheat may have 40 different gliadins encoded on multiple genes within
the wheat. Some of the chromosome specialists years ago tried to
engineer wheat that would lack the gliadins that activate celiac disease;
but there were so many different genes encoding gliadins, on different
chromosomes, that they soon realized it was an almost impossible feat.