Common psychiatric disorders such as schizophrenia, bipolar disorder and major depression share genetic risk factors related to immune function and changes in DNA expression, reports a study published online this week in Nature Neuroscience.

Hundreds of genetic differences across the human genome slightly increase the risk for psychiatric conditions such as schizophrenia. It is not clear, however, how these genetic changes affect different biological processes that then go on to alter brain function.

Gerome Breen, Peter Holmans and colleagues analyzed genetic data from over sixty thousand participants, including individuals with schizophrenia, bipolar disorder, major depression, autism spectrum disorders and attention deficit hyperactivity disorder, as well as healthy individuals. When the authors grouped the genetic data for all disorders together, they found that genes relating to histone methylation (molecular changes that alter DNA expression) and immune function are risk factors associated with the development of these disorders. This begins to identify shared biology across disorders that may help in developing targeted treatments irrespective of exact diagnosis.