Billions and billions of gene expression measurements.

Let's say you are looking for a disease biomarker. Hopefully, one better than prostate specific antigen. Next time you or your student reach for a pipette to see if a gene is expressed in a particular tissue or disease, perhaps you should first check with the public databases of gene expression. As outlined in this article, we now have hit the one million array mark. That is, one million arrays measuring gene expression across thousands of conditions (tissues, diseases, pharmacological or environmental perturbation). And each array has tens of thousands of genes so these corpora have billions of gene expression measurements. That means you'll immediately be able to see if your favorite gene is uniquely expressed in a tissue in a specific disease. Or not.

Another way to think about these corpora is that they constitute one of the largest open access biomedical libraries. A model for clinical research to emulate?

Hat tip: Atul Butte.