What is Cystinuria?
Excessive urinary excretion of cystine, along with lysine, arginine, and ornithine, arising from defective transport systems for these acids in the kidney and intestine; renal function is sometimes compromised by cystine crystalluria and nephrolithiasis. There are at least three forms of cystinuria, which are distinguished by the severity of urinary excretion of cystine in obligate carriers; all with autosomal recessive inheritance. Types I and II cystinuria are allelic disorders caused by mutation in the solute carrier family 3 gene (SLC3A1), which is an amino acid transporter gene on chromosome 2q. Type III is caused by mutation at a separate locus.