MUC1 and autosomal dominant medullary cystic kidney disease with or without hyperuricemia: Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a recently defined entity characterized by autosomal dominant inheritance, bland urinary sediment with minimal blood and protein, pathological changes of tubulointerstitial fibrosis, and slowly progressive chronic kidney disease.[1] A few genes with disease-causing mutations have been identified in ADTKD, including UMOD, REN, MUC1, SEC61A1, and HNF1B. HNF1B encodes a POU (Pit-1Oct-1/2-UNC-86) homeodomain-containing transcription factor the hepatocyte nuclear factor 1B (HNF1B).