Figure4: Variation in gene expression in health and disease.

Global gene expression was measured in 45 samples from each of five studies. Whole blood samples were drawn from healthy volunteers; the PBMC samples were isolated from whole blood drawn from healthy volunteers; the infected whole blood samples were drawn from patients who presented with a fever of at least 38.0C and a bacterial infection; the chronic lymphocytic leukemia (CLL) samples were magnetically-purified peripheral blood B cells from CLL patients; and the diffuse large B cell leukemia (DLCL) samples were bulk lymph node biopsies from DLCL patients. Of the well-measured microarray elements, 3826 were randomly selected from each group and variance was calculated for each. Variance was plotted in rank order (highest to lowest) for the genes in each of the specimen groups.