Abstract: Urea cycle disorders（UCDs），a group of genetic metabolic diseases，are caused by genetic defects in urea synthesis and related metabolic pathways，which lead to hyperammonemia and varied clinical manifestations. The severe cases of UCDs present coma，convulsions and even death.When the blood ammonia rises sharply，it can cause irreversible neurological damage. As a cure for this disease，liver transplantation should be performed as soon as possible prior to nervous injury to improve the prognosis. 

Key words: urea cycle disorder, liver transplantation, timing of surgery

摘要：  尿素循环障碍（UCDs）是一组遗传性代谢病，是由于尿素合成和相关代谢途径的遗传缺陷引起的疾病，会导致高氨血症，临床上会出现一系列的表现，严重者昏迷、抽搐甚至死亡，当血氨急剧升高时会造成不可逆的神经系统损伤，肝脏移植是尿素循环障碍的治愈手段，应该在这些患者被导致神经系统损伤前尽早实施移植手术，从而改善预后。

关键词: 尿素循环障碍, 肝脏移植, 手术时机