Recent advances have identified the genetic risks behind many human diseases, but the next big step is to observe how these genetic variations lead to the illnesses, and how we might modify or even reverse the pathologies. Xin Jin, 34, has invented a method that allows simultaneous analysis of many genes in living organs. “Previously, genetic studies were done by analyzing one gene at a time, and typically one or a few cell types at a time,” she says. Her method allows scientists to examine dozens or hundreds of genes in each experiment, and it works for many different types of organs and cells. Jin is using it to better understand how genetic changes affect mental health.