US researchers have linked mutations in 40 genes to sporadic schizophrenia. The evidence suggests that 50 percent of people with schizophrenia without a family history of the condition have 'de novo' DNA mutations that were not passed on from their parents.
Schizophrenia affects one in every 100 people during their lifetime, and commonly has a genetic component – up to ten percent of people with schizophrenia have a parent with the condition. Mutations that are not inherited occur when eggs and sperm are formed, or soon after the sperm fertilises the egg. Therefore they only affect the offspring, not the parents.
This study examined the genomes of 53 people with sporadic schizophrenia and their unaffected parents, and compared them to the genomes of 22 unaffected individuals and their parents.
The researchers, from Columbia University, USA and the University of Pretoria, South Africa, found 40 mutations in 40 different genes in the individuals with sporadic schizophrenia that were not present in either parent.
This was an unexpected result for the study author Bin Xu, who said: 'Identification of these damaging de novo mutations has fundamentally transformed our understanding of the genetic basis of schizophrenia'.
Lead researcher Professor Maria Karayiorgou of Columbia University, USA told the BBC: 'The fact that the mutations are all from different genes is particularly fascinating. It suggests that many more mutations than we suspected may contribute to schizophrenia'.
Schizophrenia is known to be a complex condition that affects a number of different neural circuits in the brain, and it is predicted that the large number of genetic pathways involved provide potential for numerous mutations.
While only a small number of the genes identified in this study are currently known to be associated with schizophrenia, the researchers believe that further research will identify links to the newly identified genes. They also believe that de novo mutations in these genes may explain why schizophrenia is so common throughout the world and appears to have little correlation to environmental factors.
Paul Jenkins, chief executive of the charity Rethink Mental Illness has welcomed the research and hopes it will help develop ways to treat or even prevent schizophrenia in the future.