Changed Relative to What? Housekeeping Genes and Normalization Strategies in Human Brain Gene Expression Studies
Changed Relative to What? Housekeeping Genes and Normalization Strategies in Human Brain Gene Expression Studies
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DOI：
10.1016/j.biopsych.2010.05.023
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发表时间：
2011-01-15
影响因子：
10.6
通讯作者：
Harrison, Paul J.
中科院分区：
文献类型：
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作者：
Tunbridge, Elizabeth M.;Eastwood, Sharon L.;Harrison, Paul J.
生物精神病学的许多研究比较了病例和对照组之间个体信使RNA的丰度，或者最近比较了基因型组之间个体信使RNA的丰度。大多数利用某种形式的标准化程序，通常表达相对于管家基因或基因（也称为参考基因）的目标转录物，以克服各种来源的实验误差。事实上，规范化是一种标准程序，其目的、原则和局限性有时被忽视，一些文件缺乏关于其实施的足够信息。在这里，我们回顾了正常化的基本原理，并认为在使用人脑组织进行的良好的精神病基因表达研究中，减少受试者间的变异性，而不是实验误差，这是正常化的主要好处。我们还回顾了管家基因类别的概念和经验基础，即，具有普遍存在和不变表达的基因。我们的结论是，证据是对任何这样简单的分类，一个更务实的，少教条主义，方法来选择和实施的参考基因是必要的，这需要考虑到特定的问题，涉及到人类脑组织的研究。这种实用主义延伸到标准化是否应该是一个或多个参考基因的问题。最后，我们提出了一些建议，以更灵活，透明和全面的数据呈现和分析方法。我们举例说明审查精神分裂症和情绪障碍的研究。
Many studies in biological psychiatry compare the abundance of individual messenger RNAs between cases and control subjects or, more recently, between genotype groups. Most utilize some form of normalization procedure, usually expressing the transcript(s) of interest relative to that of a housekeeping gene or genes (also called reference genes), to overcome various sources of experimental error. Indeed, normalization is such a standard procedure that its purpose, principles, and limitations are sometimes overlooked, and some papers lack sufficient information as to its implementation. Here, we review the rationales for normalization and argue that in well-conducted psychiatric gene expression studies using human brain tissue, it is reducing intersubject variability rather than experimental error that is the major benefit of normalization. We also review the conceptual and empirical basis for the category of housekeeping genes-i.e., genes with a ubiquitous and invariant expression. We conclude that the evidence is against any such simple categorization and that a more pragmatic, less dogmatic, approach to the selection and implementation of reference genes is required, which takes into account the particular issues that pertain to human brain tissue studies. This pragmatism extends to the issue of whether normalization should be to one or multiple reference genes. We end by making several recommendations toward a more flexible, transparent, and comprehensive approach to data presentation and analysis. We illustrate the review with examples from studies of schizophrenia and mood disorder.