Some diseases, such as forms of autism, tuberous sclerosis complex (TSC), and Rett Syndrome arise when some, but not all of the cells in a tissue such as the brain suffer an unfortunate genetic mutation early in development. This patchwork of healthy and unhealthy cells is called mosaicism. Last May Mark Zervas’s group showed how they could induce mosaicism at specific times during the development of the brain in a rodent model, producing new clues about when a mutation during development may lead to disease. Now Zervas has earned a new three-year award of $935,000 from the Defense Department’s Congressionally Directed Medical Research Program to extend his research using a novel technique to induce mosaicism in a cell in developing tissue with precise control of timing and scope. “Essentially we can induce the mutation in a single blastomere and follow the progeny of this mutant cell (its lineage) and directly compare across tissues, brain regions and cell types,” said Zervas, the Manning Assistant Professor of Biology.