With few exceptions, jumping genes - restless bits of DNA that can move freely about the genome - are forced to stay put. In patients with Rett syndrome, however, a mutation in the MeCP2 gene mobilizes so-called L1 retrotransposons in brain cells, reshuffling their genomes and possibly contributing to the symptoms of the disease when they find their way into active genes, report researchers at the Salk Institute for Biological Studies.

Their findings, published in the November 18, 2010 issue of the journal Nature, could not only explain how a single mutation can cause the baffling variability of symptoms typical of Rett syndrome but also shed new light on the complexity of molecular events that underlie psychiatric disorders such as autism and schizophrenia.