Autism is a spectrum of disorders that result in aberrant development and function of the nervous system. The behavior of some children with autism improves in response to fever. Although a great deal of progress has been made in identifying genes that contribute to autism, very little progress has been made in identifying the neural cell types and circuits that are affected by mutations in these genes, or are altered in response to fever.

Nathaniel Heintz and his colleagues at Rockefeller University in New York are using a powerful new method to identify cells whose functions are altered in two different mouse models of autism. The researchers are analyzing the data to assess the brain pathways that are altered in an effort to identify common molecular mechanisms relevant to autism. The Heintz laboratory has used the same general strategy to identify cell types that mediate the behavioral response to fever.

Although additional comparative analysis will be required to uncover the biological significance of these molecular data, one important and unexpected finding has already emerged from these studies. The researchers have discovered a direct link between MeCP2, the gene that is disrupted in Rett syndrome, and 5-hydroxymethylcytosine, a nucleotide that is abundant in human and mouse brains. This discovery has major implications for understanding Rett syndrome and perhaps other autism-related disorders.