Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common, life-threatening inherited human disorders and the most common hereditary kidney disease. It is associated with large interfamilial and intrafamilial variability, which can be explained to a large extent by its genetic heterogeneity and modifier genes. It is also the most common of the inherited cystic kidney diseases — a group of disorders with related but distinct pathogenesis, characterized by the development of renal cysts and various extrarenal manifestations, which in case of ADPKD include cysts in other organs, such as the liver, seminal vesicles, pancreas, and arachnoid membrane, as well as other abnormalities, such as intracranial aneurysms and dolichoectasias, aortic root dilatation and aneurysms, mitral valve prolapse, and abdominal wall hernias. Over 50% of patients with ADPKD eventually develop end stage kidney disease and require dialysis or kidney transplantation. ADPKD is estimated to affect at least one in every 1000 individuals worldwide, making this disease the most common inherited kidney disorder with a diagnosed prevalence of 1:2000 and incidence of 1:3000-1:8000 in a global scale.
Cystic kidney disease refers to a wide range of hereditary, developmental, and acquired conditions and with the inclusion of neoplasms with cystic changes, over 40 classifications and subtypes have been identified. Depending on the disease classification, the presentation may be at birth, or much later into adult life. Cystic disease may involve one or both kidneys and may, or may not, occur in the presence of other anomalies. A higher incidence is found in males and prevalence increases with age. Renal cysts have been reported in more than 50% of patients over the age of 50. Typically, cysts grow up to 2.88 mm annually and may cause related pain and/or hemorrhage.
Fibrocystin is a large, receptor-like protein that is thought to be involved in the tubulogenesis and/or maintenance of duct-lumen architecture of epithelium. FPC associates with the primary cilia of epithelial cells and co-localizes with the Pkd2 gene product polycystin-2 (PC2), suggesting that these two proteins may function in a common molecular pathway.
TRPP is a family of transient receptor potential ion channels which when mutated can cause polycystic kidney disease.
Polycystin 1 (PC1) is a protein that in humans is encoded by the PKD1 gene. Mutations of PKD1 are associated with most cases of autosomal dominant polycystic kidney disease, a severe hereditary disorder of the kidneys characterised by the development of renal cysts and severe kidney dysfunction.
Transient receptor potential canonical 1 (TRPC1) is a protein that in humans is encoded by the TRPC1 gene.
Frizzled-4(Fz-4) is a protein that in humans is encoded by the FZD4 gene. Fz-4 has also been designated as CD344.
Glucosidase 2 subunit beta is an enzyme that in humans is encoded by the PRKCSH gene.
V-type proton ATPase 16 kDa proteolipid subunit is an enzyme that in humans is encoded by the ATP6V0C gene.
Polycystic kidney disease 2-like 1 protein also known as transient receptor potential polycystic 2 is a protein that in humans is encoded by the PKD2L1 gene.
HCLS1-associated protein X-1 is a protein that in humans is encoded by the HAX1 gene.
Translocation protein SEC63 homolog is a protein that in humans is encoded by the SEC63 gene.
Transducin beta-like protein 3 is a protein that in humans is encoded by the TBL3 gene.
Polycystic kidney disease is a genetic disorder in which the renal tubules become structurally abnormal, resulting in the development and growth of multiple cysts within the kidney. These cysts may begin to develop in utero, in infancy, in childhood, or in adulthood. Cysts are non-functioning tubules filled with fluid pumped into them, which range in size from microscopic to enormous, crushing adjacent normal tubules and eventually rendering them non-functional as well.
Autosomal recessive polycystic kidney disease (ARPKD) is the recessive form of polycystic kidney disease. It is associated with a group of congenital fibrocystic syndromes. Mutations in the PKHD1 cause ARPKD.
Polycystic kidney disease 2-like 2 protein (PKD2L2) also known as transient receptor potential polycystic 5 (TRPP5) is a protein that in humans is encoded by the PKD2L2 gene.
PKD domain was first identified in the polycystic kidney disease protein, polycystin-1, and contains an Ig-like fold consisting of a beta-sandwich of seven strands in two sheets with a Greek key topology, although some members have additional strands. Polycystin-1 is a large cell-surface glycoprotein involved in adhesive protein–protein and protein–carbohydrate interactions; however it is not clear if the PKD domain mediates any of these interactions.
The GAIN domain is a protein domain found in a number of cell surface receptors, including adhesion-GPCRs and polycystic kidney disease proteins PKD1 and PKD2. The domain is involved in the self-cleavage of these transmembrane receptors, and has been shown to be crucial for their function. Point mutations within the GAIN domain of PKD1 and GPR56 are known to cause polycystic kidney disease and polymicrogyria, respectively.
The Polycystin Cation Channel (PCC) Family consists of several transporters ranging in size from 500 to over 4000 amino acyl residues (aas) in length and exhibiting between 5 and 18 transmembrane segments (TMSs). This family is a constituent of the Voltage-Gated Ion Channel (VIC) Superfamily. These transporters generally catalyze the export of cations. A representative list of proteins belonging to the PCC family can be found in the Transporter Classification Database.
Polycystic kidney disease 3 (autosomal dominant) is a protein that in humans is encoded by the PKD3 gene.
