POLYCYSTIC KIDNEY DISEASE
The kidneys are two organs in the lower abdomen where excess fluid and waste is filtered from the blood to produce urine. Structures inside the kidney called nephrons allow as much blood as possible to be exposed to allow for efficient filtering. Polycystic kidney disease causes many fluid-filled cysts to form in the kidneys, which take up space and disrupt kidney function. This disease is inherited by passing on the mutated version of the gene, which is an autosomal dominant gene. Symptoms include high blood pressure, hematuria, kidney stones, andpain in the back or sides, all as a result of insufficient filtering caused by the cysts. There are no treatments of the root cause of polycystic kidney disease as more research and not much is known about why the cysts are actually produced. Once the kidney fails, a kidney transplant is a possibility. Symptoms may also be treated.
The gene locus responsible for this disease is FCYT, sometimes called the PKDH1 gene, and is located on chromosome 6. The PKDH1 gene produces fibrocystin, a protein in kidney cells that is responsible for signalling, adhesion, repulsion, and proliferation of kidney cells. The type of mutation that causes this disease is either insertion or deletion, which is when another base pair is either added or deleted from the mRNA or DNA during transcription or replication respectively. This mutation creates a small and nonfunctional version of the protein. Without this protein, kidney cells are not signalling efficiently, and proliferation is increased. Cysts begin to form in the kidney due to increased and uncontrolled proliferation which disrupt kidney function, eventually leading to kidney failure.
Chromosome 6, gene PKDH1
Cilia also play a role in polycystic kidney disease. These organelles on the surface of the cell membrane are responsible for signalling and cell cycle regulation in kidney cells. Since cilia are involved in the proliferation of kidney cells and cyclin-dependent kinase (CDK) inhibitor stops proliferation, it may be used to stop cyst progression in polycystic kidney disease. Currently, CKD inhibitor research is the only big in-the-works treatment for the root cause of polycystic kidney disease.
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Delling, M., DeCaen, P. G., Doerner, J. F., Febvay, S., & Clapham, D. E. (2013). Primary cilia are specialized calcium signalling organelles. Nature, 504(7479), 311.
Genetics Home Reference. (n.d.) Retrieved from www.ghr.nlm.nih.gov
Now for the renal side of the story. (n.d). Harvard Health Letter, 30(11), 4.