Since F11r-/- mice are highly susceptible to liver injury [32–34] and since deficiency of other tight junction proteins, namely tight junction protein 2 and claudin-1, is associated with cholestatic liver disease [35, 36], to explain the proband ́s phenotype as a consequence of JAM1 deficiency tempted us. The gene discussed is CLDN1; the disease is Cholestatic liver disease.