Inherited disorder of primary (sensory) cilia characterized by cystic expansion of the kidneys producing progressive kidney enlargement and renal insufficiency, in addition to various extrarenal manifestations.
Genetically heterogeneous group of disorders that are caused by mutations in genes with products that localize to the cilium–centrosome complex.
Motile cilia: Respiratory epithelial function, fertility, and determination of left-right orientation
Primary (or sensory) cilia: Antennae for cells, sensing the extracullar environment and transducing signals back to the cell to facilitate its response. These functions are critically important in cell proliferation, differentiation, and maintenance.
Ciliopathies cause a wide range of overlapping syndromes that include fibrocystic diseases of the kidney and liver as well as disparate abnormalities of other organ systems.
Polycystic kidney disease (PKD/PCKD):
Inherited disorder of primary (or sensory) cilia characterized by cystic expansion of the kidneys producing progressive kidney enlargement and renal insufficiency, in addition to various extrarenal manifestations.
ARPKD: Abnormality of renal tubular (collecting duct) development
ADPKD: Abnormality of renal tubule homeostasis
Other renal abnormalities: Nephronophthisis, glomerulocystic disease, and medullary sponge kidney
Hepatic fibrocystic disease:
In both ARPKD and ADPKD, the liver is also involved with fibrocystic disease caused by ductal plate malformation (DPM), which manifests as characteristic liver pathologies
Congenital hepatic fibrosis (CHF) (in ARPKD)
Polycystic liver disease
In addition, renal and hepatic fibrocystic disease may accompany abnormalities of other organ systems in ciliopathy syndromes:
Orofaciodigital type 1 syndrome
Autosomal dominant PKD (ARPKD):
Given that the number of renal cysts increases with age, a minimum number of unilateral or bilateral cysts is sufficient to make a presumptive diagnosis:
15-39 years: ≥ 3 Unilateral/bulateral cysts
40-59 years: ≥ 2 bilateral cysts
≥ 60 years: ≥ 4 bilateral cysts
Autosomal recessive PKD (ARPKD):
In utero, the diagnosis is suggested by the presence of oligohydramnios, kidney enlargement, and the absence of urine in the fetal bladder, findings typically detectable by US at 18–20 weeks gestation.
Nephronophthisis (NPHP): Autosomal recessive renal ciliopathy characterized by aspecific symptoms (i.e., urine concentration, polydipsia, and polyuria), and additional features of ciliopathy syndrome, such as retinal defects, liver fibrosis, skeletal abnormalities, and brain developmental disorders
Renal Cystic Dysplasia: Characterized by cysts in renal cortex, distended collecting ducts, and poorly developed medullary pyramids. Cystic renal dysplasia may be associated with several urologic abnormalities, including ureteropelvic and ureterovesicular junction obstruction, neurogenic bladder, ureterocele, and prune belly syndrome.
Other (rare) renal phenotypes: Horseshoe kidneys and lobulated kidneys. Moreover, cilium dysfunction can increase the risk of urinary tract infections and kidney stones.