Discovery of a mutant gene responsible for a disease is a milestone, but for most conditions, it may be only a first step towards a treatment or cure. Understanding Rett Syndrome, an autism spectrum disorder, is further complicated by the fact that the implicated gene controls a suite of other genes. Two papers, published in today's Nature Neuroscience and Nature, reveal key steps in how mutations in the gene for methyl CpG-binding protein cause the condition.