Abstract: Objective To explore the clinical characteristics and treatment of neonatal methylmalonic academia(MMA). Method The clinical data of 7 patients with neonatal MMA were analyzed and the diagnoses were confirmed by gas chromatography-mass spectrometry(GC/MS). Results The patients consisted of 3 males and 4 females, whose age of onset ranged from 0 to 6 days with all 7 cases early in the first week after birth.The main clinical manifestations were weak reaction(6 cases), poor feeding(7 cases), hyperpnea(3 cases), convulsion(2 cases), hypotonia(7 cases), et al.6 cases presented with thrombocytopenia.The laboratory findings showed metabolic acidosis in 6 cases, hyperammonemia in 4 cases and remarkable elevation of urinary methylmalonicacid concentration in all cases.Some abnormalities were noted by the brain CT or MR in 2 cases of 5.2 cases died at a short time after giving up therapy, 1 case died at the age of 3-month after giving up therapy, 1 case follow-up failed to.2 cases received therapy of vitamin B₁₂ and supplementation of L-carnitine with restricted-protein diet and showed a favorable outcome with no symptoms for a period ranging from 1 year to 1 years and 9 months.1 case received therapy of vitamin B₁₂ and supplementation of L-carnitine with restricted-protein diet, but no effect and died at the age of 4-month. Conclusions The clinical manifestations of neonatal MMA are nonspecific.GC/MS can be used to confirm the diagnosis.Early diagnosis and early treatment is the key to improve the prognosis.

Key words: methylmalonic acid, vitamin B₁₂, mass fragmentography

摘要： 目的 观察新生儿甲基丙二酸血症(methylmalonic acidemia, MMA)的临床特征, 探讨治疗方法。方法 对八一儿童医院足月NICU 2011年9月-2013年2月7例应用气相色谱-质谱法(gas chromatography-mass spectrometry, GC/MS)进行尿或血有机酸分析确诊的新生儿MMA的临床资料进行分析。结果 7例患儿中男3例, 女4例;发病日龄0～6 d, 7例均在生后1周内发病。主要表现有反应差6例, 喂养困难7例, 3例呼吸急促, 抽搐2例, 肌张力减低7例, 血小板减少6例, 血气分析提示酸中毒6例, 高氨血症4例, 7例尿甲基丙二酸浓度明显增高。5例行头颅CT或头颅MR检查, 2例检查异常。2例放弃治疗出院后死亡, 1例出院后终止治疗, 于生后3月死亡, 1例出院后失访, 2例确诊患儿接受维生素B₁₂治疗, 同时予低蛋白饮食及左旋肉碱, 临床症状完全消失。1例虽接受维生素B₁₂、左旋肉碱治疗及低蛋白饮食, 效果不佳, 生后4月死亡。结论 新生儿MMA的临床表现是非特异性的, GC/MS尿有机酸分析可确诊本病, 早期发现和治疗对改善预后有重要作用。

关键词: 甲基丙二酸, 维生素B₁₂, 气相色谱-质谱法