Late onset hyperornithinemia-hyperammonemia-homocitrullinuria syndrome - how web searching by the family solved unexplained unconsciousness: a case report.

Background: Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome, a rare inherited urea cycle disorder, can remain undiagnosed for decades and suddenly turn into an acute life-threatening state. Adult presentation of hyperornithinemia-hyperammonemia-homocitrullinuria syndrome has rarely been described, but is potentially underdiagnosed in the emergency room. In the case of acute hyperammonemia, prompt diagnosis is essential to minimize the risk of brain damage and death.