PKD2 and autosomal dominant polycystic kidney disease: The most prevalent form of PKD, autosomal dominant polycystic kidney disease (ADPKD), is in most cases caused by mutations in the PKD1 gene or, less commonly, in PKD2. PKD1 encodes polycystin-1, which is a receptor-like protein thought to be a receptor for various WNT ligands.3PKD2 encodes polycystin-2, which is a known ion channel with some selectivity for calcium ions.