Stuart Orkin, MD, a Howard Hughes Medical Institute investigator at Children’s Hospital Boston, is pursuing cancer stem cells on two fronts. He is particularly interested in identifying the cell of origin of a type of infant leukemia that is strongly associated with Down syndrome in children. A gene known as GATA 1, which is a master differentiation gene, is mutated in every case. Under normal conditions, this gene is important for blood cell development, but in infant leukemia this process is disrupted, because the mutation appears to affect cells that have not yet developed into mature blood cells.