HNF1B mutations can mimic ADPKD with important consequences for prognosis, the likelihood of comorbidities (for example, congenital hepatic fibrosis in PKHD1 or maturity onset diabetes of the young type 5 (MODY5) in HNF1B) and the risk of disease in siblings54. The gene discussed is PKHD1; the disease is renal cysts and diabetes syndrome.