TGM2 and selective IgA deficiency disease: Generally, IgAD is found 10 to 15 times higher in patients with CD (1.30%) compared with the healthy individuals (0.13% to 0.25%), which may yield false-negative results.17 In patients diagnosed with low IgA or IgA deficiency, IgG-based testing (IgG DGPs and tTG-IgG) is recommended for further validation,19 especially if IgA-based serology assay is negative.