Abstract: Objective To discuss the clinical characteristics,blood amino acid and urinary organic acid changes,the relationship between clinical phenotype and genotype in methylmalonic acidemia(MMA). Method The clinical data,blood amino acid,urinary organic acid and gene results of the 10 patients diagnosed with MMA were analyzed,which were from the developmental pediatrics department of Shengjing Hospital of China Medical University during August 2011 to December 2012. Results 10 patients,age of onset ranged from 5 days to 2 years and 5 months.The main clinical manifestations included poor feeding (2 cases),poor weight gain(1 case),repeated vomiting (2 cases),repeated convulsions (1 case),developmental retardation (3 cases),developmental degradation (1 case) and musclar dystonia (3 cases).The laboratry findings showed metabolic acidosis in three cases,hyperammonemia in seven cases and hyperhomocysteinemia in six cases.The typical MRI changes were found in 3 cases,nonspecific change were found in 4 cases.4 cases were detected related gene mutation,diagnosed three cases of cblC subtype,one case of mut-subtype.In patients reactive to VitB12 treatment,urinary MMA average decreased rate was 6.45,which of the blood C3 was 2.05,and C3/C2 was 1.64. Conclusions Except for the nonspecific clinical features,it is vulnerable to have metabolic acidosis,hyperammonemia and hyperhomocysteinemia; the brain MRI appears both typical changes and non-specific changes;the decline level of urinary MMA is a sensitive index in patients reactive to VitB12 treatment;genetic testing is used for clinical parting,estimating prognosis and prenatal diagnosis.

Key words: methylmalonic acidemia, clinical manifestations , sgenetic typing, GC/MS

摘要： 目的 探讨甲基丙二酸血症的临床特征,治疗前后血氨基酸、尿有机酸的变化及基因型与临床表型的关系。方法 对中国医科大学附属盛京医院发育儿科2011年8月-2012年12月10例确诊的甲基丙二酸血症患儿的临床资料,血氨基酸、尿有机酸及基因结果进行分析。结果 10例患儿的发病年龄为出生5 d~2岁5月,主要临床表现包括喂养困难2例,体重不增1例,反复呕吐2例,顽固性抽搐1例,发育落后3例,发育倒退1例,肌张力异常3例。代谢性酸中毒3例,血氨增高7例,伴同型半胱氨酸增高6例。头部MRI典型改变3例,非特异性改变4例。VitB12 有效型尿MMA平均下降倍率为6.45倍,血丙酰肉碱(C3)为2.05倍,血丙酰肉碱/乙酰肉碱(C3/C2)为1.64倍。4例患儿检测到相关基因突变,基因分型3例为cblC亚型,1例为mut-亚型。 结论 甲基丙二酸血症除了表现为非特异性临床特征以外,易发生代谢性酸中毒、高氨血症和同型半胱氨酸血症;头部MRI既可以为典型改变也可以为非特异性改变;尿MMA可作为VitB12治疗有效的敏感指标;基因检测可进一步帮助临床分型、估计预后及产前诊断。

关键词: 甲基丙二酸血症, 临床表现, 基因分型, 血氨基酸及有机酸