Cystinuria is an inherited condition which causes stones of amino acid cysteine in the kidneys, bladder and urethra. The disease is passed down from parents to children. The accumulation of cysteine in the kidneys occur due to the defect in the genes.The main functions of the kidneys include absorption of the minerals and proteins back into the body from the food, filtration of blood in order to remove the toxic waste and production of the urine which is excreted out from the body.
In Cystinuria, the amino acid cysteine builds up and forms stones in the kidneys instead of going back to the blood stream. These stones get stuck in the kidneys, bladder and urethra causing pain the stomach. Smaller stones may pass through urination while large stones need to be removed surgically.
It is caused by the mutations of SLC3A1 or SLC7A9 genes. These two genes plays role in the making of two parts of a protein complex which is commonly found in the kidneys. This protein complex controls the reabsorption of certain amino acids in to the blood stream from the urine. The ability of the protein complex to reabsorb the amino acids is disrupted by the mutations of these two genes making amino acids to become concentrated in the urine. High the levels of cystine in the urine, more the chances of getting cystinuria.
The condition is inherited in an autosomal recessive pattern. In autosomal recessive pattern, both the copies of the gene have mutations for each cell. The parents of an individual with this condition carry one copy of the mutated gene but the signs and symptoms may not appear in them.
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