The use of DNA microarray technologies has come a long way in the decade and a half since their introduction by Schena and colleagues in 1995 (1). In this issue, Sibille and colleagues (2) triangulate several techniques based on DNA microarrays to study tran-scriptional variation in major depressive disorder compared to normal controls. DNA microarrays assay a "snapshot" of the transcriptome (the composition of mRNAs being expressed) by measuring the concentration of mRNA molecules after conversion to DNA by a bacterial enzyme called reverse transcriptase. The technique can detect which genes vary their expression across different experimental conditions or disease states. By simultaneously measuring the expression of many genes in a tissue sample, the strategy takes an unbiased "discovery science" approach to identifying genes with altered expression profiles when compared to normal or control conditions
展开▼
