Comparisons between all seropositive cases from the different patient groups revealed that only 1 patient with active AD had both elevated IgA-anti-TG1 and IgA-anti-TG3 antibody levels, however, patients presenting with CD or with AD and concomitant CD tended to be seropositive for IgA-anti-TG1 and/or IgA-anti-TG3 together with IgA-anti-TG2 and IgA-anti-DGP seropositivity (see Additional file 1: Table S1 for more details). Here, TGM2 is linked to Alzheimer disease.