- autosomal recessive

- defect of renal PCT and intestinal amino acid transporter that prevents reabsorption of Cystein, Ornithine, Lysine, and Arginine (COLA)

- excess cystein in the urine can lead to recurrent precipitation of cystine stones

Treatment:- urinary alkalinization (eg potassium citrate, acetazolamide)- chelating agents (eg penicillamine)

- urinary cyanide-nitroprusside test is diagnostic