Chace D H, Hillman S L, Millington D S, Kahler S G, Roe C R, Naylor E W
Department of Pediatrics, Duke University Medical Center, Research Triangle Park, NC 27709.
Clin Chem. 1995 Jan;41(1):62-8.
We report a new method for the diagnosis of maple syrup urine disease (MSUD) from dried blood spots on newborn screening cards based on tandem mass spectrometry (MS-MS). The mean +/- SD concentration of Leu plus Ile in normal newborns was 151 +/- 47 mumol/L (n = 1096); for Val, 131 +/- 58 mumol/L (n = 791). SDs were lower when the concentrations of these amino acids were expressed relative to that of Phe. The mean ratio for Leu + Ile to Phe was 2.5 +/- 0.49; for Val to Phe, 2.18 +/- 0.51. These results compare well with values previously reported in the literature. With these criteria, samples from a collection categorized by a bacterial inhibition assay as normal or falsely positive for MSUD were normal by MS-MS [(Leu + Ile): Phe < 5.0]. Samples from confirmed MSUD patients were categorized as abnormal [(Leu+Ile): Phe > 9.0] by MS-MS.
我们报告了一种基于串联质谱法（MS-MS）从新生儿筛查卡片上的干血斑诊断枫糖尿症（MSUD）的新方法。正常新生儿中亮氨酸加异亮氨酸的平均浓度±标准差为151±47μmol/L（n = 1096）；缬氨酸为131±58μmol/L（n = 791）。当这些氨基酸的浓度相对于苯丙氨酸的浓度表示时，标准差较低。亮氨酸+异亮氨酸与苯丙氨酸的平均比值为2.5±0.49；缬氨酸与苯丙氨酸的比值为2.18±0.51。这些结果与文献中先前报道的值相当。根据这些标准，通过细菌抑制试验分类为正常或MSUD假阳性的一组样本经MS-MS检测为正常[（亮氨酸+异亮氨酸）：苯丙氨酸<5.0]。确诊的MSUD患者的样本经MS-MS检测分类为异常[（亮氨酸+异亮氨酸）：苯丙氨酸>9.0]。
