目的 探讨新生儿型氨甲酰磷酸合成酶Ⅰ缺乏症（CPS1D）的临床特点。 方法 回顾分析1例新生儿型 CPS1D患儿的临床资料及基因学检测结果，并复习相关文献。 结果 患儿，女，3d。以不吃、不动、气促、抽搐等非特异 表现起病，予禁食、抗感染、呼吸支持等治疗病情一度好转，恢复喂养后病情加重、进展迅速。头颅MRI示广泛脑白质 病变；血氨?>?500μmol/L；基因检测发现致病基因CPS1存在第20号外显子c.2407C?>?G (p.803， R?>?G)及第4号外显子 C.323G?>?A(p.108， G?>?E)两处杂合突变，最终确诊为CPS1D。 结论 对出生时正常，建立喂养后出现不明原因喂养困难、 抽搐及意识障碍的新生儿，若血氨水平明显增高，应尽早行血、尿氨基酸及基因分析明确诊断。

Objective To explore the clinical characteristics of neonatal-onset carbamoyl phosphate synthetase I deficiency (CPS1D). Methods Clinical data and result of genetic detection of one neonate with CPS1D were retrospectively analyzed. The pertinent literature was reviewed. Results A 3-day old girl, with onset symptoms of nonspecific performance, such as poor feeding, less activity, tachypnea, and seizures. After fasting, anti-infection, and respiratory support etc. the condition was improved. However, the condition deteriorated and developed rapidly after feeding restarted. MRI showed extensive cerebral white matter lesions. Blood ammonia?>?500 μmol/L. Gene detection found two heterozygous mutations in pathogenic gene CPS1 in twentieth exon of c.2407C?>?G (p.803, R, G) and fourth exon C.323G?>?A (p.108, G, E), according to which CPS1D was diagnosed finally. Conclusions For neonate with normal birth, had feeding difficulty, seizures, and consciousness disorder after establishment of normal feeding, if blood ammonia level significantly increased, the blood and urine amino acids analysis and gene detection should be performed to confirm the diagnosis.