Especially PSORS1 positive patients are prone to develop the guttate form of psoriasis,57 a form that has been strongly associated with throat infections with β-haemolytic streptococci.58 Recently a variant in the 5′ region of another member of the mucin family, MUC19, has been newly identified to be relevant in the pathogenesis of Crohn’s disease.59 This might indicate a more general role of these epithelial proteins in the pathogenesis of diseases with compromised barrier function. This evidence concerns the gene HLA-C and psoriasis.