HNF1B and cystic kidney disease: HNF1β (hepatocyte nuclear factor 1β), a transcription factor involved in the embryogenesis of the pancreas and liver and expressed in the Wolffian duct from a very early stage of kidney development [77], was the second gene to be identified following the discovery of a heterozygous mutation in two siblings with renal cysts and diabetes [16,78] and then reported in individuals with isolated CAKUT [44,79].