Most of us know that the genetic information that makes us who we are is encoded in the DNA in our cells. But that information has to be transcribed and translated into other molecules that actually make the body work. That process is called gene expression.
Think of the DNA in each cell as a giant recipe book for making stroganoff or baked beans or brownies. It’s the job of cells to read those recipes and decide which ones to make and how much. Some cells specialize in making lots of brownies, others make small amounts of spinach salad.
What’s interesting to Purvesh Khatri, PhD, assistant professor of medicine, is that when we are sick, the pattern of genes that cells express changes in ways that are consistent and quantifiable. Think more salad, fewer brownies for one disease; more lentil soup and pumpkin curry for another. In the past year, he’s published a small body of scientific work showing that he and others can use preexisting data to identify those changes in gene expression from blood or other tissue samples.
Each time Khatri identifies a set of genes whose expression changes for a given disease, he has the prospect of a diagnostic test. And all the work is done with public data that already exists.
Khatri began in 2016 with a cheap, simple gene-expression test for tuberculosis, a common, contagious and deadly disease that is surprisingly hard to diagnose.
Now, as 2016 comes to a close, Khatri has published a new paper describing a gene-expression test for the autoimmune disease systemic sclerosis, a type of scleroderma. He and his team call it the 4S test. Systemic sclerosis causes a profound thickening and stiffening of the skin that can make it difficult to open or close the hands, to open the eyes or even to walk. The disease, which can also affect internal organs, is disfiguring, painful, and can be fatal.
Yet, as I explained in a news release:
By measuring the activity of genes in tiny skin samples, the researchers were able to predict disease progression in patients as much as a year earlier than clinicians who used standard methods for evaluating patients.
For all the details about the system sclerosis test, check out the news release or even the paper. But the bigger message may be that the menu planning capabilities of our cells may hold at least as many clues to our health as genes.