Complex sentence: If unrecognized, the condition leads to liver failure--but not kernicterus, as the liver is still able to conjugate bilirubin, and conjugated bilirubin is unable to cross the blood-brain barrier.
Split into simpler sentences: If unrecognized, the condition leads to liver failure but not (as one might think) to kernicterus. This is because the liver is still able to conjugate bilirubin, and conjugated bilirubin is unable to cross the blood-brain barrier.