Polycystic Kidney Disease

Polycystic kidney disease (PKD) results from single gene defects transmitted as either autosomal dominant or autosomal recessive traits. Different ages of onset, variability in kidney disease progression, and a diverse array of extrarenal manifestations distinguish these disorders. In autosomal dominant PKD (ADPKD), defects in either of two causative genes, PKD1 or PKD2, can initiate cyst formation resulting from a germline mutation in one allele and a somatic mutation in the second allele. The respective protein products, polycystin-1 (PC1) and polycystin-2 (PC2), form a receptor-channel complex that is variably expressed in the plasma cell membrane, as well as in the primary apical cilia membrane. Autosomal recessive PKD (ARPKD) results from mutations in the PKHD1 gene, which encodes the protein product, fibrocystin/polyductin (FPC), which is also expressed in primary cilia. This chapter discusses PKD genetics, clinical and genetic diagnosis, management of organ-specific complications, and future directions for disease monitoring and potential therapies.