PKD2 and autosomal dominant polycystic kidney disease: Together, mutations in Pkd1 and Pkd2 account for 78% and 15% of ADPKD cases, respectively, leaving 7% of cases undetected by these two genes.[6]Pkd1’s expansive gene length, featuring 46 exons, encodes polycystin-1 (PC1)—a protein integral to calcium signaling and essential for maintaining tubular epithelial cell polarity and function, with its 4303 amino acid residues.