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Cystinuria
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Cystinuria is an inherited kidney disease. Autosomal recessive means a person has to inherit the altered gene from both parents to have it. What fails is the proximal tubular reabsorption of cystine, an amino acid, that is, one of the building blocks proteins are made of.
The kidney filters the blood and then takes back what is useful. Normally the cystine that has been filtered returns to the blood in that stretch of the tubule; in cystinuria it does not return, it stays in the urine, and it keeps concentrating there. Cystine is the least soluble of all the essential amino acids, and that is why it crystallizes: it is like too much sugar in a glass, where what will not dissolve settles at the bottom.
When those crystals grow, they turn into stones that can lodge in the kidney or the bladder. Stones are the only manifestation of cystinuria, which comes from mutations in the SLC3A1 or SLC7A9 genes.
In brief
Cystinuria is an autosomal recessive genetic defect in the proximal tubular reabsorption of cystine, an amino acid in proteins.
Normally filtered cystine returns to the blood; when it does not, it concentrates in the urine and crystallizes, because it is the least soluble essential amino acid.
It is like too much sugar in a glass: what will not dissolve settles at the bottom.
Large crystals become stones that can lodge in the kidney or bladder, and they are the only manifestation of this disease of the SLC3A1 or SLC7A9 genes.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingCystinuria, StatPearlsPublished
- MedlinePlus Genetics, U.S. National Library of MedicineCystinuria, MedlinePlus GeneticsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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