PKD2 and autosomal dominant polycystic kidney disease: Although polycystin-1 (PC1), encoded by the Pkd1 gene, and Polycystin-2 (PC2), encoded by the Pkd2 gene, are mutated in autosomal dominant polycystic kidney disease [28], [29], [30], [31], loss of polycystin function in mice also causes a severe skeletal phenotype.