Abstract: The child started  with digestive system discomfort as the primary symptom,resulting in intracranial hemorrhage and brain death  due to high blood ammonia.The results of gene test during hospitalization indicated that the mutation ofc.10063C>G  was responsible.  The clinical manifestation of this disease is lack of specificity,mainly relying on the tandem mass spectrometry analysis of hematuria,and the gold standard(genetic detection)for the diagnosis of the disease. Ornithine transcarbamylase deficiency（OTCD）  patients  have a high mortality rate  and a poor prognosis.There is no clinical standard  treatment  plan at present.Clinicians need to improve the awareness,diagnosis,treatment level,andearly detection of high blood ammonia.Early blood  purification  techniques may alleviate symptoms.

Key words: ornithine carbamoyltransferase deficiency disease, hyperammonemia, subarachnoid hemorrhage, genetic testing