Cystinuria: definition, epidemiology and clinical aspects.

Cystinuria ia an inheritable autosomal recessive disorder of amino acids transport affecting the epithelial cells of the renal tubules and gastrointestinal tract. It is characterized by abnormal concentrations of cystine and the other dibasic amino acids in the urine, resulting in a risk of renal stone formation because of the low solubility of cystine in urine. According to the recent advances in molecular genetics, two genes have been identified as responsible for this disease (SLC3A1 and SLC7A9), but other unknown genes may be involved in cystinuria.