Cystinuria

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**Cystinuria**
*Classifications and external resources*
ICD-10	E72.0
ICD-9	270.0

Cystinuria is an inherited autosomal recessive disorder and is characterized by the formation of cystine stones in the kidneys, ureter, and bladder.

1 Causes
2 Occurrence in other animals
3 Types
4 See also
5 External links

[edit] Causes

Cystinuria is characterized by the inadequate reabsorption of cystine during the filtering process in the kidneys, thus resulting in an excessive concentration of this amino acid. Cystine will precipitate out of the urine, if the urine is neutral or acidic, and form crystals or stones in the kidneys, ureters, or bladder.

Mutations in the SLC3A1 and SLC7A9 genes cause cystinuria. The SLC3A1 and SLC7A9 genes provide instructions for producing the two parts of a transporter protein that is made primarily in the kidneys. Normally this protein allows certain amino acids, including cystine, to be reabsorbed into the blood from the filtered fluid that will become urine. Mutations in either of these genes disrupt the ability of this transporter protein to reabsorb these amino acids, allowing them to become concentrated in the urine. As the levels of cystine in the urine increase, the crystals typical of cystinuria are able to form. The other amino acids that are not reabsorbed do not create crystals in urine. The disorder affects 1 in 10,000 people and is inherited in an autosomal recessive pattern.