Fibrocystin seems to exert some effects via the same intracellular signaling pathways which are also dysregulated in the closely related autosomal dominant polycystic kidney disease (ADPKD) (6, 7), but the specific mechanisms leading to cysts and the peculiar clinical phenotype of the disease are still to be identified and described in detail. This evidence concerns the gene PKHD1 and autosomal dominant polycystic kidney disease.