CD79A and dermatitis herpetiformis, familial: The optimal cut-off for the Anti-tTG IgA ELISA in all combinations (DH patients versus healthy control; DH patients versus IgA/neutrophil-mediated non-DH dermatoses; combined groups) of examined groups is 17.199 RU/mL (manufacturer's cut-off is 20 RU/mL).