TGM2 and systemic lupus erythematosus: This fits with the presence of a wide variety of auto-Abs found in SLE subjects with CD (Supplementary Table S4) and the high frequency of low titer and unspecific IgA Abs against tTG found in our series; these findings fit with previous studies demonstrating frequent false positive serology for anti-gliadin, tTG Abs and EMA in patients with systemic ADs (Table 1, Table 2 and Table 3).