WIKIMEDIA, NATIONAL LIBRARY OF MEDICINEScientists compared gene expression in the brains of people with autism and schizophrenia with that in controls, finding 106 genes that were expressed at lower levels in the brains of the former groups, according to a study published last month (May 24) in Translational Psychiatry. The findings add to growing evidence that the disorders may be linked in some way.
“On the one hand, it’s exciting because it tells us that there’s a lot of overlap,” Jeremy Willsey, a professor of psychiatry at the University of California, San Francisco, who was not involved in the work, told Spectrum News. “On the other hand, these are fairly general things that are overlapping.”
Previously, Dan Arking, a professor of genetic medicine at Johns Hopkins University in Baltimore, Maryland, and colleagues measured gene expression in postmortem brain tissue from 32 people with autism and 40 controls. In the present study, the researchers compared these data with gene-expression information collected by the Stanley Medical Research Institute in Chevy Chase, Maryland, from the postmortem brain tissue of 31 people with schizophrenia, 25 with bipolar disorder, and 26 controls.
Arking’s team found that the genes expressed in the brains of people with autism and schizophrenia are involved in the development of neurons—particularly long-range projections—and synapses. The researchers did not find significant similarities in gene expression between the brains of people with autism and those with bipolar disorder, or between the brains of people with bipolar disorder and those with schizophrenia. However, the team did identify two genes on chromosome 12, IQSEC3 and COPS7A, which were expressed at low levels in the brains of people with autism, people with schizophrenia, and those with bipolar disorder.
The findings agree with those of previous studies, which have found genetic commonalities among these three disorders (although some research suggests that schizophrenia may be more similar to bipolar disorder than to autism).
It’s not yet clear whether the similarities between autism and schizophrenia gene expression reflect a common mechanism or are simply the result of other brain changes, study coauthor Shannon Ellis, a graduate student in Arking’s lab, told Spectrum News. “We can’t say anything about whether this is cause or effect,” Ellis said.