Diagnostic tests based on blood samples are mainstays of the healthcare system. Adding RNA sequencing (RNA-seq) can extract more information from blood samples, including a snapshot of all the genes active in a patient’s blood cells. Such a snapshot can tell us about the current condition of the patient’s immune system, whether there are cancer cells in the blood and/or whether blood cells are fighting an infection. Drs. Michael Wilson and Adam Shlien of The Hospital for Sick Children are developing an RNA-based clinical test called SANGRE (systematic analysis of blood gene regulation in blood) that will provide unprecedented power to use RNA expression as a routine and affordable test that can better diagnose disease, disrupting clinical practice and improving the health of Canadians.