Reported non-malignant cystic renal diseases included simple cysts, autosomal dominant or recessive polycystic kidney disease, medullary cystic kidney disease, nephronophthisis, multicystic kidney disease, renal cysts and diabetes syndrome/HNF1B-associated renal disease and a medullary sponge kidney. Here, HNF1B is linked to medullary sponge kidney.