Identification of new putative biomarkers for autism in urine by mass spectrometry

Introduction: Autism spectrum disorder (ASD) is characterized by conditions affecting social interaction, communication and behavior, and sensory sensitivity. Studies have reported an association of ASD with various metabolic alterations. The aim of this study was to develop a pilot study of a non-targeted metabolomics and proteomics approach to identify candidate metabolic biomarkers in urine from children with ASD. Material and Methods: Prospective cross-sectional study with case-control design. Cases were male children (n = 22) with ASD, aged 3-10 years, and controls were neurotypical children (n = 22) matched for sex and age. Metabolomic analysis was performed by mass spectrometry with laser desorption ionization and time-of-flight analysis (MALDI-TOF). Proteomic analysis was performed by liquid chromatography coupled to mass spectrometry (LC-MS). Results: Metabolomic analysis identified the 655 mass spectrum with high frequency in the urine samples of both groups, classified as coproporphyrins II and IV. The 1911 Da spectrum showed a higher frequency in urine samples from children with ASD and was classified as GT2 ganglioside (d18:0/14:0). Proteomic analysis also detected the compound with molecular weight of 1911 and its fragments, but they were classified as uromodulins. Conclusion: The non-targeted metabolomic and proteomic approach allowed the identification of promising candidate biomarkers for TEA, although the results of the analyses differed with respect to the nature of the identified compounds.

引言：自闭症谱系障碍（Autism spectrum disorder, ASD）是以影响社交互动、沟通、行为及感觉敏感性的各类病症为特征的一类疾病。已有研究证实，ASD与多种代谢异常存在相关性。本研究旨在开展一项预实验，采用非靶向代谢组学（metabolomics）与蛋白质组学（proteomics）方法，从自闭症患儿的尿液样本中筛选潜在的代谢生物标志物。

材料与方法：本研究采用前瞻性横断面病例对照研究设计。病例组为22名年龄3~10岁的男性自闭症患儿，对照组为22名性别与年龄相匹配的神经发育正常儿童。代谢组学分析采用激光解吸电离-飞行时间质谱（MALDI-TOF）技术完成；蛋白质组学分析采用液相色谱-质谱联用（LC-MS）技术开展。

结果：代谢组学分析在两组儿童的尿液样本中均检测到高频出现的质荷比为655的质谱峰，经鉴定为粪卟啉II与粪卟啉IV。分子量为1911 Da的质谱峰在自闭症患儿的尿液样本中出现频率更高，经鉴定为GT2神经节苷脂（d18:0/14:0）。蛋白质组学分析同样检测到分子量为1911的化合物及其片段，但经鉴定为尿调蛋白。

结论：本研究采用的非靶向代谢组学与蛋白质组学方法，成功鉴定出针对TEA的潜在候选生物标志物；不过两类分析在鉴定化合物的性质方面存在差异。