The involvement of tTG in the pathogenesis of CD could be also due to another distinct but interdependent pathway via a gliadin-derived peptide deamidation reaction (Figure 1).Gluten peptides are specifically recognized by human leukocyte antigen (HLA)-DQ2/DQ8,a class II major histocompatibility complex [21]. The gene discussed is TGM2; the disease is Cowden disease.