Argininosuccinic aciduria (ASA) is a rare inherited disorder that causes elevated blood ammonia levels.If ammonia buildup in the blood is not detected and treated promptly, it can cause brain damage and even death.It is caused by changes (mutations) in the ASL gene that result in a deficiency.ASL (argininosuccinate lyase) is an enzyme that breaks down and eliminates nitrogen from the body.  Read More