McLoughlin Kevin, Turteltaub Ken, Bankaitis-Davis Danute, Gerren Richard, Siconolfi Lisa, Storm Kathleen, Cheronis John, Trollinger David, Macejak Dennis, Tryon Victor, Bevilacqua Michael
Lawrence Livermore National Laboratory, Livermore, CA, USA.
Mol Med. 2006 Jul-Aug;12(7-8):185-95. doi: 10.2119/2006-00018.McLoughlin.
The use of quantitative gene expression analysis for the diagnosis, prognosis, and monitoring of disease requires the ability to distinguish pathophysiological changes from natural variations. To characterize these variations in apparently healthy subjects, quantitative real-time PCR was used to measure various immune response genes in whole blood collected from blood bank donors. In a single-time-point study of 131 donors, of 48 target genes, 43 were consistently expressed and 34 followed approximately log-normal distribution. Most transcripts showed a limited dynamic range of expression across subjects. Specifically, 36 genes had standard deviations (SDs) of 0.44 to 0.79 cycle threshold (C(T)) units, corresponding to less than a 3-fold variation in expression. Separately, a longitudinal study of 8 healthy individuals demonstrated a total dynamic range (> 2 standard error units) of 2- to 4-fold in most genes. In contrast, a study of whole blood gene expression in 6 volunteers injected with LPS showed 15 genes changing in expression 10- to 90-fold within 2 to 5 h and returning to within normal range within 21 hours. This work demonstrates that (1) the dynamic range of expression of many immune response genes is limited among healthy subjects; (2) expression levels for most genes analyzed are approximately log-normally distributed; and (3) individuals exposed to an infusion of bacterial endotoxin (lipopolysaccharide), show gene expression profiles that can be readily distinguished from those of a healthy population. These results suggest that normal reference ranges can be established for gene expression assays, providing critical standards for the diagnosis and management of disease.
利用定量基因表达分析进行疾病的诊断、预后评估和监测，需要具备区分病理生理变化与自然变异的能力。为了描述明显健康受试者中的这些变异，采用定量实时聚合酶链反应（qRT-PCR）来测量从血库供体采集的全血中各种免疫反应基因。在一项对131名供体的单点研究中，48个靶基因中有43个持续表达，34个大致呈对数正态分布。大多数转录本在不同受试者间显示出有限的表达动态范围。具体而言，36个基因的标准差（SD）为0.44至0.79个循环阈值（C(T)）单位，对应于表达水平小于3倍的变化。另外，一项对8名健康个体的纵向研究表明，大多数基因的总动态范围（>2个标准误单位）为2至4倍。相比之下，一项对6名注射脂多糖（LPS）的志愿者的全血基因表达研究显示，有15个基因在2至5小时内表达变化了10至90倍，并在21小时内恢复到正常范围内。这项工作表明：（1）许多免疫反应基因在健康受试者中的表达动态范围有限；（2）所分析的大多数基因的表达水平大致呈对数正态分布；（3）接触细菌内毒素（脂多糖）输注的个体，其基因表达谱可与健康人群的基因表达谱轻易区分开来。这些结果表明，可以为基因表达检测建立正常参考范围，为疾病的诊断和管理提供关键标准。
