This new paper by Sullivan et al. is extremely important and noteworthy. This is a careful scientific study that establishes that blood-based gene expression can be useful and informative as a proxy for the expression of some genes in other tissues throughout the body. In so doing, this study validates prior work that rested (rather tenuously at the time) on the assumption that gene expression in the blood could reflect what is happening with some genes in the brain. The results of this study did not show perfect correspondence between gene expression levels in the blood and brain, but this is not unexpected. Different genes must be activated to greater or lesser degrees in distinct tissues, otherwise all organs would perform the same functions. However, there was a notable amount of similarity among the tissues, which validates the position I and others have held for some time: that is, the expression levels of approximately 33 percent of genes are heritable, and thus may be similarly regulated in all tissues; for those genes, expression in the blood is useful and informative...  Read more

This new paper by Sullivan et al. is extremely important and noteworthy. This is a careful scientific study that establishes that blood-based gene expression can be useful and informative as a proxy for the expression of some genes in other tissues throughout the body. In so doing, this study validates prior work that rested (rather tenuously at the time) on the assumption that gene expression in the blood could reflect what is happening with some genes in the brain. The results of this study did not show perfect correspondence between gene expression levels in the blood and brain, but this is not unexpected. Different genes must be activated to greater or lesser degrees in distinct tissues, otherwise all organs would perform the same functions. However, there was a notable amount of similarity among the tissues, which validates the position I and others have held for some time: that is, the expression levels of approximately 33 percent of genes are heritable, and thus may be similarly regulated in all tissues; for those genes, expression in the blood is useful and informative for expression in the brain, since the levels would be similar in both tissues regardless of environmental or other biological factors. These genes may thus be prime candidate etiologic factors and biomarkers for the disorder. This paper lays the groundwork for continued exploration of blood-based gene expression profiling in the search of risk factors and biomarkers for schizophrenia and other mental disorders.