To have the symptoms of cystinuria, you must inherit the faulty gene from both parents. Your children will also inherit a copy of the faulty gene from you.
Cystinuria is caused by too much of an amino acid called cystine in the urine. After entering the kidneys, most cystine normally dissolves and goes back into the bloodstream. But people with cystinuria have a genetic defect that interferes with this process. As a result, cystine builds up in the urine and forms crystals or stones, which may get stuck in the kidneys, ureters, or bladder.
About one in every 10,000 people have cystinuria. Cystine stones are most common in young adults under age 40. Less than 3% of urinary tract stones are cystine stones.