Abstract: Methylmalonic acidemia or aciduria （MMA） is a common organic acidemia/aciduria in China. It is caused by the metabolic disorder of methylmalonyl-CoA mutase （MCM） or its coenzyme cobalamin （cbl）， resulting in a large number of metabolites accumulating in the body， and causing damage to nerves， liver， kidney， bone marrow and other organs. Due to the diverse clinical features and lack of specificity， it is particularly prone to misdiagnosis and missed diagnosis，and finally it has to be diagnosed by biochemical and metabolic examination and genetic testing. Once diagnosed， the patients with isolated MMA with no response or partial response to vitamin B12 should start limiting protein intake as early as possible. For patients with response to vitamin B12，long-term treatment with vitamin B12 can be given （hydroxycobalamin preferred）. MMA patients with hyperhomocysteinemia can be given oral betaine to reduce homocysteine levels. For MMA patients with secondary hyperammonemia， treatment with carglumic acid is of good efficacy. For patients with poor response to treatment， liver （or liver and kidney） transplantation may be attempted. Gene therapy has made some progress in animal experiments in recent years， and it is expected that it can be applied to patients in the future to achieve new breakthroughs.

Key words: methylmalonic acidemia, methylmalonic aciduria, methylmalonyl-CoA mutase, cobalamin, diagnosis, treatment

摘要： 甲基丙二酸血症（methylmalonic acidemia， MMA），亦称甲基丙二酸尿症（methylmalonic aciduria， MMA）是一种常见的有机酸血/尿症，是由于甲基丙二酰辅酶A变位酶（methylmalonyl-CoA mutase， MCM）或其辅酶钴胺素（cobalamin， cbl）代谢障碍，导致代谢产物在体内大量蓄积，引起神经、肝、肾、骨髓等多脏器、多系统损伤。由于MMA临床表现形式多样，加上往往缺乏特异性，特别容易误诊和漏诊；最终需通过生化代谢检查及基因检测来确诊。一旦确诊，维生素B12无效或部分有效的单纯型MMA患者，应尽早开始限制蛋白质摄入。对于维生素B12有效型的患者，可予维生素B12（首选羟钴胺）长期治疗；合并高同型半胱氨酸血症患者，联合口服甜菜碱以降低同型半胱氨酸水平；继发高氨血症者可给予卡谷氨酸等降氨治疗，效果良好。对于治疗效果差的患者，可尝试肝（或肝肾联合）移植。近年来基因疗法在动物实验中取得一定进展，期待未来能应用于临床，实现新的突破。

关键词: 甲基丙二酸血症, 甲基丙二酸尿症, 甲基丙二酰辅酶A变位酶, 钴胺素, 诊断, 治疗