Non-celiac gluten sensitivity (NCGS) is an intestinal tissue transglutaminase (TG2)- and IgE-independent form of GS. NCGS is approximately 6× more prevalent than the classical celiac disease (CD), and its incidence is on the rise. Because of its high relative prevalence and striking resemblance to other forms of GS, there is a greater need to develop new and accurate diagnostic assays to facilitate its definitive diagnosis. As the presence of serum anti-gliadin antibodies (AGA) in the absence of TG2 antibodies is suggestive of NCGS, several reports have recommended AGA immunoassays for differential diagnosis. Although AGA immunoassays are in general suitable for diagnostic purpose, to corroborate NCGS and to distinguish it from CD, a simultaneous use of CD-specific diagnostics, i.e., TG2 antibody-based assay, is also required. Due to lower accuracy of AGA assays than those of TG2-based ones, there will always be a chance (estimated to 5–10%) of misdiagnosing NCGS. Moreover, AGA-based diagnostics would not take into consideration the fact that NCGS is potentially triggered by not only gluten but also other molecules such as fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs). Therefore, a second generation of assays needs to be developed to differentiate NCGS from CD with high accuracy.
Part of the book: Celiac Disease and Non-Celiac Gluten Sensitivity