Yu Dan, Lu Guoyan, Mowshica Rajah, Cheng Yan, Zhao Fumin
Department of Pediatrics, West China Second University Hospital, Sichuan University.
Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education.
Medicine (Baltimore). 2019 Aug;98(33):e16827. doi: 10.1097/MD.0000000000016827.
Ornithine transcarbamylase deficiency (OTCD) is a common metabolic disease of urea circulation disorder. We reported the clinical, brain imaging and genetic characteristics of 2 cases with OTCD. The patients' clinical features, novel gene mutations, cranial MR specific imaging changes and blood tandem mass spectrometry, and urine gas chromatography-mass spectrometry were, retrospectively, analyzed.
Patient 1 was a 1.6-year-old female. She was admitted to the hospital with 2-months history of general irritability and disturbance of consciousness for a day. Patient 2 was a 3.7-year-old female. She was admitted to the hospital due to decline of language ability and irritability for 5 days. Blood tandem mass spectrometry and urine gas chromatography-mass spectrometry showed uracil and orotate increased significantly in urine while amino acids in the urea cycle ring were in the normal range. The features of brain MRI are consistent with those of urea circulatory disorders. Gene detection showed 1 novel mutation in the OTC gene (c.658C>T) in patient 1 and, 1 novel mutation (c.298+2T>G) in the OTC gene in patient 2.
Combined with metabolic screening and gene detection, both patients were diagnosed with OTCD.
The patients' condition improved after following a low protein diet and receiving treatments for decreasing blood ammonia, energy supplement, correcting acid-base imbalance, and other symptomatic treatments.
After prompt symptomatic treatment, the consciousness and cognition of the children improved. Besides, liver function also improved significantly.
For patients with neurological symptoms and unexplained increase in transaminase and ammonia, OTCD should be considered as a possible diagnosis. Brain MRI can help the diagnosis of genetic metabolic encephalopathy and reflect the level of brain injury. Metabolic screening and genetic detection are helpful to make a confirmed diagnosis.
鸟氨酸转氨甲酰酶缺乏症（OTCD）是尿素循环障碍常见的代谢性疾病。我们报告了2例OTCD患者的临床、脑影像学及遗传学特征。回顾性分析了患者的临床特征、新的基因突变、头颅磁共振成像（MR）特异性影像学改变以及血液串联质谱和尿液气相色谱 - 质谱结果。
患者1为1.6岁女性。因2个月来全身易激惹及意识障碍1天入院。患者2为3.7岁女性。因语言能力下降及易激惹5天入院。血液串联质谱和尿液气相色谱 - 质谱显示尿中尿嘧啶和乳清酸显著升高，而尿素循环环中的氨基酸在正常范围内。脑MRI特征与尿素循环障碍相符。基因检测显示患者1的OTC基因有1个新突变（c.658C>T），患者2的OTC基因有1个新突变（c.298+2T>G）。
结合代谢筛查和基因检测，两名患者均被诊断为OTCD。
患者采用低蛋白饮食，并接受降血氨、补充能量、纠正酸碱失衡等对症治疗后病情改善。
经过及时对症治疗，患儿意识和认知功能改善。此外，肝功能也显著改善。
对于有神经症状且转氨酶和血氨不明原因升高的患者，应考虑OTCD作为可能的诊断。脑MRI有助于诊断遗传代谢性脑病并反映脑损伤程度。代谢筛查和基因检测有助于确诊。
