Cystinuria
| Cystinuria | |
|---|---|
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| Chemical structure of cystine formed from L-cysteine (under biological conditions) | |
| Classification and external resources | |
| Specialty | endocrinology |
| ICD-10 | E72.0 |
| ICD-9-CM | 270.0 |
| OMIM | 220100 |
| DiseasesDB | 3339 |
| MedlinePlus | 000346 |
| eMedicine | med/498 |
| MeSH | D003555 |
Cystinuria is an inherited autosomal recessivedisease that is characterized by high concentrations of the amino acid cystine in the urine, leading to the formation of cystine stones in the kidneys, ureter, and bladder. It is a type of aminoaciduria.
Cystinuria is an autosomal recessive disease, which means that the defective gene responsible for the disease is located on an autosome, and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disease. The parents of an individual with an autosomal recessive disease both carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disease. Although signs and symptoms are rare, there are some directly and indirectly associated with cystinuria. These sign and symptoms consist of 1) hematuria- blood in the urine, 2) flank pain – pain in the side due to kidney pain, 3) renal colic – intense, cramping pain due to stones in the urinary tract, 4) obstructive uropathy- urinary tract disease due to obstruction, and 5) urinary tract infections.
Cystinuria is caused by mutations in the SLC3A1 and SLC7A9 genes. These defects prevent proper reabsorption of basic, or positively charged, amino acids: Cysteine, lysine, ornithine, arginine. Under normal circumstances, this protein allows certain amino acids, including cysteine, 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, resulting in kidney stones. Cystine crystals form hexagonal-shaped crystals that can be viewed upon microscopic analysis of the urine. The other amino acids that are not reabsorbed do not create crystals in urine.
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