TGM2 and allergic disease: In this regard, the method used for differential diagnostic searches for suspected HI should include: (1) maintenance of a food diary for 2–4 weeks to identify a causal relationship between the occurrence of the corresponding symptomatology and the use of certain nutrients; (2) exclusion of food IgE-mediated allergies (skin prick test and specific IgE study), celiac disease (antibodies to gliadin, endomysia, and tissue transglutaminase), and inflammatory bowel diseases (analysis for calprotectin, colonoscopy).