TGFB1 and acrodermatitis enteropathica: The major peak of TGF-β1 at the middle stage of infection in experimental animals, and its expression in AE patients who are diagnosed at a similar stage, suggest that although lower levels may initiate immune tolerance as early as the early stage, the cytokine becomes prominent later, when both maintenance of the tolerance state and development of fibrosis are at stake (Fig. 11).