Answer Bank

Frequently Asked Questions


What exactly is a biomarker, and why is it so essential?

The definition of a biomarker (or biological marker) is a biological substance produced by an organism in response to a disease state, that can be detected by any laboratory or imaging technique thus allowing an assessment of the disease presence and/or progression. As an example, the detection of antibodies against the enzyme tissue transglutaminase (the tTG test) in the blood is used to detect the presence of celiac disease. In non-celiac gluten sensitivity, research has not identified any biomarkers. This means we don’t currently have an objective parameter that we can use as a base for our diagnosis of this condition. Anti-gliadin antibodies (AGA) are not a good marker for non-celiac gluten sensitivity. While approximately 50% of patients with non-celiac gluten sensitivity have elevated AGA, up to 20% of healthy individuals also have this same state, hence we cannot rely on this as a biomarker. In fact, not only do half of non-celiac gluten sensitive patients have normal AGA, but if the prevalence of non-celiac gluten sensitivity is ~2%, it means that 21 of 100 persons will have high AGA, but of these 21 only 1 will be non-celiac gluten sensitive. Therefore, AGA has no value as a biomarker. Given the unavailability of a biomarker, one can immediately understand how impossible it is to make an accurate estimate of the true prevalence of non-celiac gluten sensitivity. February, 2013