Scientists have demonstrated that there is a genetic component to schizophrenia, but it has proven difficult to identify which genes are most important to developing the disease. Individual risk genes identified are most likely to confer only modest risk. Environmental factors are also known to play a role, but how gene–environment interactions work together to produce the illness is still unclear.

New research, led in part by two-time NARSAD Independent Investigator Grantee, Tadafumi Kato, M.D., Ph.D., Senior Team Leader for Molecular Dynamics of Mental Disorders at RIKEN Brain Science Institute in Japan, shows that people with schizophrenia have more "jumping genes"—bits of DNA that can move around and insert themselves into genes and disrupt their function. Jumping genes can either remain silent, doing nothing; they can churn out their own genetic products; or they can alter the activity of neighboring genes, sometimes with deleterious effects. But jumping genes also make up nearly half of the current human genome, leading scientists to believe that their effects could also be linked to human evolution.

Recent research by Foundation Scientific Council Member, Fred Gage, Ph.D., Professor, Laboratory of Genetics and Adler Chair for Research on Age-Related Neurodegenerative Disease at The Salk Institute, has demonstrated that L1 is one of the most common jumping genes in humans. Dr. Gage and his colleagues have found that elevated L1 levels are associated with mental illnesses such as Rett syndrome, an autism spectrum disorder, and other neurological diseases. However, “no one had looked very carefully” to see if the gene might also contribute to schizophrenia, he says.

This new research, reported online January 2nd in Neuron, investigates whether elevated levels of L1 may also be linked to schizophrenia. The research team compared the DNA from the brains of people with schizophrenia to that of healthy people and found higher levels of L1 present with the illness. They also found that simulating a viral infection in pregnant mice (an environmental trigger believed to be linked to schizophrenia) led to their offspring having higher levels of L1 in their brain tissue. The findings suggest a link between schizophrenia and high L1 levels, both genetically and through gene–environment interactions. Dr. Kato says he hopes that the "new view" that environmental factors can trigger or deter genetic changes involved in the disease will help remove some of the disorder's stigma.

Learn more about this research through the Schizophrenia Research Forum

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