Autosomal dominant polycystic kidney disease (ADPKD, MIM #173900; # 613095) typically arises from germline mutations inactivating the PKD1 or PKD2 genes, and affects approximately 1 in 1000 individuals, and has a phenotype of epithelial cell overgrowth, resulting in extensive replacement of normal renal ductal and tubular structure with fluid-filled cysts. The gene discussed is PKD1; the disease is autosomal dominant polycystic kidney disease.