--about that low IgA level--while the genetic profile that results in low overall IgA is not uncommon, it can have a skewing effect on the Celiac/gluten sensitivity tests, particularly the IgA anti-Gliadin and IgA anti-transglutaminase tests (the latter is more specific for the villious intestinal damage of frank Celiac). Low IgA levels may mean that one can get a "false negative" on these IgA measurements--there may simply not be enough IgA antibody being produced by these to measure, and therefore some people may have celiac/gluten sensitivity without showing up positive on these.

JCC's The Gluten File has info on this, as well as alternative testing that is sometimes done in such situations:

http://neurotalk.psychcentral.com/thread1872.html