adult-onset citrullinemia type I (MONDO_0016601, a Monarch Disease Ontology identifier) is a form of citrullinemia type I characterized clinically by adult onset of symptoms including variable hyperammonemia and less striking neurological findings which may include intense headache, scotomas, migraine-like episodes, ataxia, slurred speech, lethargy and drowsiness. Serious increased intracranial pressure may occur. Also known as: adult-onset citrullinemia type 1, late-onset citrullinemia type 1, late-onset citrullinemia type I.