Digenic inheritance has also already been reported to have a prognostic role in other kidney diseases, such as congenital nephrotic syndrome (mutations in NPHS1 and NPHS2) (31), autosomal dominant polycystic kidney disease (mutations in PKD1 and PKD2) (32) and Bartter's syndrome (33). This evidence concerns the gene PKD2 and autosomal dominant polycystic kidney disease.