目的　了解北京地区遗传性代谢性疾病(IMD)的发病情况。方法　利用气相色谱-质谱法(GC-MS)对IMD高危儿进行尿液化学分析。结果　411例IMD高危儿中检测出代谢异常269例(65.5%)，其中确诊IMD 19例(4. 6%)，包括甲基丙二酸血症15例，丙酸血症、高苯丙氨酸血症、尿素循环异常和焦谷氨酸尿症各1例；疑似IMD 22例(5.4%)，包括乳酸血症13例，原发性甘油尿症5例，脂肪酸代谢异常4例，Citrin缺陷症、酪氨酸血症、半乳糖血症、3-甲基巴豆酰辅酶A羧化酶缺乏症、枫糖尿症各1例；其他代谢异常228例(55.5%)，表现为尿乳酸、蔗糖、乳糖、半乳糖、N-乙酰酪氨酸、琥珀酸、双羧酸水平增高以及丝氨酸/苏氨酸比例异常等。结论　甲基丙二酸血症为北京地区最常见的IMD，对不能明确病因的患儿应尽早行GC-MS检测，必要时联合应用串联质谱检测和基因分析诊断。

Objective　To learn the incidence of the inherited metabolic diseases in Beijing. Methods Urine samples were analyzed by gas chromatography-mass spectrometry??GC-MS??for inherited metabolic diseases in high risky infants in Beijing . Results Urine samples from 411 high risky infants were analyzed by gas chromatography-mass spectrometry. 269 cases (65.5%) were detected to have metabolic abnormalities, including 19 cases (4.6%) diagnosed of inherited metabolic diseases in which there were 15 cases of methylmalonic academia and 1 case each of propionic academia, hyperphenylalaninemia, urea cycle abnormality and pyroglutamic aciduria. There were 22 suspected cases (5.4%) of inherited metabolic diseases including 13 cases of lactic acidosis, 5 cases of primary glycerol aciduria, 4 cases of fatty acid metabolic disorders including 1 case each of Citrin defects, tyrosinemia, galactosemia 3-methylcrotonoyl coenzyme A carboxylase deficiency and maple syrup urine disease. There were also 228 cases (55.5%) of metabolic abnormalities, such as increasing urine levels of lactic acid, sucrose,lactose, galactose, N-acetyl tyrosine, succinic acid, dicarboxylic acid and abnormal serine/threonine ratio. Conclusions Methylmalonic academia might be the most common inherited metabolic diseases in high risky infants in Beijing. For infants with clinical manifestations but unclear etiology, GC-MS should be performed. MS-MS and gene analysis could be combined if necessary.