TGM2 and irritable bowel syndrome: They also found that increased anti-gliadin (AGA) IgG and/or tissue-transglutaminase antibodies were more frequent in IBS patients who expressed the HLA-DQ2 compared to HLA-DQ2–negative IBS patients (P < .05) and that a normal GI symptom score after GFD was achieved more frequently in those patients who were HLA-DQ2-positive and/or had celiac disease–associated IgG antibodies.