TGM2 and psoriasis: Studies by Michaëlsson et al. showed that three months of gluten-free diet improves skin biopsy anomalies (reduction in Ki67 positive cells and tissue transglutaminase-tTG expression in dermis) and psoriasis severity (reduction of psoriasis area and PASI score from 5.5 ± 4.5 to 3.6 ± 3) in patients with psoriasis and positive IgA-AGA or IgG-AGA antibodies [163,164].