This is a tough one. When my kids were born with it in the late 80s/early 90s we were told 13 years or so. However with assertive treatment and care, they reached 16 Years old at which time they got liver transplants. Since being transplanted at 16 Years old they have been symptom free and are expected to live a full life. If you or anyone you know has Arginino succinic aciduria I storongly urge you to seek a live transplant which essentially provides a full cure.