Cystinuria is a genetic disorder characterized by the excessive excretion of cystine, an amino acid, in the urine. This condition results from a defect in the renal tubular transport of certain amino acids, leading to the formation of cystine stones in the kidneys and urinary tract. Symptoms may include recurrent kidney stones, pain, and urinary tract infections. Management often involves increased fluid intake, dietary modifications, and medications to prevent stone formation.