--on celiac/gluten sensitivity testing:

The anit-transglutaminase IgA test is the most specific for the villious atrophy of frank celiac.

The anti-gliadin IgG test is the most sensitive, but least specific, test forgluten sensitivity. A positive here means that the body is making antibodies to gluten on the most basic level. As Dr. Hadjivassiliou has pointed out people with an isolated positive anti-gliadin IgG test are more likely to have gluten sensitivity that presents without gastric symptoms, and may even have neurologic symptoms as first presentation. (Gluten sensitivity/celiac is now known to be linked to neurologic problems, most specifically cerebellar ataxia and peripheral neuropathy, and these may involve direct attack on nerves and not just nutrient deficiencies from malabsoprtion.) Moreover, while celiac has traditionally been linked with the DQ-2 and DQ-8 HLA genetic profiles, this is being called into question; Dr. Hadjivassiliou has found the DQ-1 subtype is often prone to the isolated anti-gliadin IgG finding and to non-gastric symptoms.