Psychiatric Genetic Epidemiology & Neurobiology Laboratory (PsychGENe Lab), Departments of Psychiatry and Behavioral Sciences & Neuroscience and Physiology, Medical Genetics Research Center, SUNY Upstate Medical University, Syracuse, New York.
Am J Med Genet B Neuropsychiatr Genet. 2013 Oct;162B(7):595-603. doi: 10.1002/ajmg.b.32150.
In this article, we review studies detailing the correspondence between peripheral blood and brain tissue across various domains of high-throughput -omic analysis in order to provide a context for evaluating blood-based biomarker studies. Specifically, we reviewed seven studies comparing patterns of DNA methylation (i.e., an aspect of the epigenome), eight articles comparing patterns of gene expression (i.e., the transcriptome), and three articles comparing patterns of protein expression (i.e., the proteome). Our review of the epigenomic literature suggests that CpG-island methylation levels are generally highly correlated (r = 0.90) between blood and brain. Our review of transcriptomic studies suggests that between 35% and 80% of known transcripts are present in both brain and blood tissue samples; estimates of cross-tissue correlation in expression levels were found to range from 0.25 to 0.64, with stronger correlations observed among particular subsets of genes. Relative to the epigenome and transcriptome, the proteome has not been as fully compared between brain and blood samples, highlighting an important area for future work as whole-proteome profiling methods mature. Beyond reviewing the relevant studies, we discuss some of the assumptions, methodological issues, and gaps in knowledge that should be addressed in order to better understand how the multiple "-omes" of the brain are reflected in the peripheral blood. A better understanding of these relationships is a critical precursor to the validation of biomarkers for brain disorders.
在本文中，我们回顾了详细研究外周血和脑组织之间在高通量 - 组学分析的各个领域的对应关系，以便为评估基于血液的生物标志物研究提供背景。具体来说，我们综述了比较 DNA 甲基化模式（即表观基因组的一个方面）的 7 项研究，比较基因表达模式（即转录组）的 8 篇文章，以及比较蛋白质表达模式（即蛋白质组）的 3 篇文章。我们对表观基因组文献的回顾表明，CpG 岛甲基化水平在血液和大脑之间通常高度相关（r = 0.90）。我们对转录组研究的综述表明，在大脑和血液组织样本中存在 35%至 80%的已知转录本；发现表达水平的跨组织相关性范围在 0.25 到 0.64 之间，在特定基因子集之间观察到更强的相关性。与表观基因组和转录组相比，蛋白质组在大脑和血液样本之间尚未得到充分比较，突出了未来工作的一个重要领域，因为全蛋白质组谱分析方法不断成熟。除了回顾相关研究外，我们还讨论了一些假设、方法学问题和知识差距，这些都应该在为了更好地了解大脑的多个“组”如何反映在周围血液中，这些都应该得到解决。更好地理解这些关系是验证大脑疾病生物标志物的关键前提。
