"There are going to be differences due to mutations, but the general systems operate in a nearly identical fashion from person to person," Tompkins said. "This paper is the first to really identify that the differences in genomic response are quantitative. The systems of the young patient versus the older patient are qualitatively identical. The degree with which the genes regulate up or down might be less and deviations might return to normal more quickly or slowly. But there are no new genes or pathways to recruit, and the direction of regulation is the same in both."
Erratic immune response: 'That's why they die'
The Princeton researchers analyzed data on patients who had been observed for 28 days by other researchers involved in the IHRI project and whose health status had been documented through almost 400 clinical variables describing the patients' condition. As part of the effort to better understand the genomic activity of these trauma victims, Stanford University researchers involved in the project analyzed blood samples to create a profile of white-blood-cell gene expression for each patient.
Using this data collected by the Stanford researchers, the Princeton team first created a system to classify each patient's condition. Tan used documentation of the patients' condition and prognosis to develop five distinct categories based on the likelihood of death from multiple organ failure -- all patients in the fifth category eventually died. At the same time, Desai condensed the mass of gene data into a scale illustrating how each gene's expression changed over time for each patient.
Storey and his colleagues used these scales to identify which genes exhibited the greatest change in expression as a patient's health degenerated. They narrowed the initial 50,000 expressions to the top 3,000 gene expressions
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