Disorders of urea cycle account for up to 60% of severe neonatal hyperamoniemias. The base of this cycle disorders results in a deficit of its enzymes. Deficiency of the enzyme ornithine transcarbamylase is the most frequently detected. The prognosis depends on the degree of enzyme deficiency, age, early diagnosis and initiation of treatment. We report the case of a teenager who was treated with prednisone because of a peripheral facial palsy. He showed a progressive worsening and died a few days later. The high levels of ammonia made suspect a congenital disorder of urea cycle. The postmortem genetic study confirmed it. We studied the family and advised carriers. We reflect about the importance of the neonatal screening programs and their applicability for detection of inborn errors of metabolism.