In many patients with<unk> , kidney dysfunction is not clinically apparent until 40 or 50 years of life. However, an increasing body of evidence suggests the formation of renal cysts starts in utero. Cysts initially form as small dilations in renal tubules, which then expand to form fluid-filled cavities of different sizes. Factors suggested to lead to cystogenesis include a germline mutation in one of the polycystin gene alleles, a somatic second hit that leads to the loss of the normal allele, and a third hit, which can be a renal insult that triggers cell proliferation,and an injury response. Due to numerous similarities between the pathophysiology of<unk>  and the pathophysiology of the renal response to injury,<unk>  has been described as a state of aberrant and persistent activation of renal injury response pathways. In the progression of the disease, continued dilation of the tubules through increased cell proliferation, fluid secretion, and separation from the parental tubule lead to the formation of cysts.<unk> , together with many other diseases that present with renal cysts, can be classified into a family of diseases known as ciliopathies. Epithelial cells of the renal tubules, including all the segments of the nephron and the collecting ducts (with the exception of intercalated cells) show the presence of a single primary apical cilium. Polycystin-1, the protein encoded by the<unk>  gene, is present on these cilia and is thought to sense the flow with its large extracellular domains, activating the calcium channels associated with polycystin-2, the product of gene PKD2, as a result of the genetic setting of<unk>  as explained in the genetics sub-section above. Epithelial cell proliferation and fluid secretion that lead to cystogenesis are two hallmark features in<unk> . During the early stages of cystogenesis, cysts are attached to their parental renal tubules and a derivative of the glomerular filtrate enters the cysts. Once these cysts expand to approximately 2 mm in diameter, the cyst closes off from its parental tubule and after that fluid can only enter the cysts through transepithelial secretion, which in turn is suggested to increase due to secondary effects from an increased intracellular concentration of cyclic AMP (cAMP). Clinically, the insidious increase in the number and size of renal cysts translates as a progressive increment in kidney volume. Studies led by Mayo Clinic professionals established that the total kidney volume (TKV) in a large cohort of<unk>  patients was 1060 ± 642ml with a mean increase of 204ml over three years, or 5.27% per year in the natural course of the disease, among other important, novel findings that were extensively studied for the first time. Illustration of<unk>  and PKD2 proteins at the cell membrane
Autosomal dominant polycystic kidney disease
Autosomal recessive polycystic kidney disease
Medullary cystic kidney disease
Glomerulocystic kidney disease
Medullary sponge kidney
Juvenile nephronophthisis
Horseshoe kidney
Multicystic dysplastic kidney