--the test for the IgA antibody to tranglutaminase, an antibody to a gluten-reaction enzyme that is often found in people with celiac and/or gluten sensitivity.

It is currently considered to be the most specific antibody for frank celiac, and it appears to be at least roughly correlated with the amount of damage to the small intestinal villi. However, it is not a perfect measure; some 20% of people who were found to have villous damage on biopsy did NOT have levels of this or other antibodies (i.e,, anti-gliadin IgA, IgG) beyond "normal" ranges. (There's some question as to what really constitutes a normal range, of course--it's been argued that those whose bodies do not react to gluten would not have ANY levels of antibody.)

What did the test results show?