Common
genetic1 variants2 contribute to the risk of
schizophrenia（精神分裂症） and bipolar
disorder3, an international research consortium has discovered. Schizophrenia and bipolar disorder are common and often
devastating4 brain
disorders5, affecting around one per cent of the world's population. A team including Cardiff University scientists has found new
molecular6 evidence that 11 genetic regions have strong links with these diseases, including six regions not
previously7 observed. The researchers also found that many of these
DNA8 variations contribute to both diseases.
The findings, reported by the Psychiatric Genome-Wide Association Study Consortium (PGC), represent significant advances in these severe and
debilitating9 disorders.
The findings, based on genetic data from tens of thousands of patients, have just been published online in two papers in the journal Nature Genetics. Professors Michael O'Donovan, Michael Owen and Nick Craddock from the MRC Centre for Neuropsychiatric Genetics and Genomics at Cardiff's School of Medicine, Cardiff University, made a significant contribution of data, analysis and management to the study.
Professor O'Donovan said: "The genetic variants we have identified are common in the population -- everyone carries many of them, but people with the disorders carry more.
"The success of this study demonstrates the need for international co-ordination in harnessing data from very large samples to exploit the power of genetics to reveal new insights. Over the next two years we expect to have data from study samples that are three or four times larger than those we have now, and this can be expected to have the same impact for our research as ever more powerful particle accelerators have had in physics."
Professor Owen added: "Many
genes10 are clearly involved in these disorders and it will be a few years yet till we are able to see a large part of the picture. However, for the first time, we are in a position to make
tentative（试验性的） functional11 links between some of the genes identified.
"One particularly exciting finding is the involvement of a type of
molecule12, known as a microRNA, which acts as a molecular switch to turn off other genes. This microRNA is also known to regulate aspects of the development and maturation of nerve cells in the brain. The findings suggest disruption of these development processes as likely factors in the origins of mental disorder."
Both schizophrenia and bipolar disorder usually strike in late adolescence13 or early adulthood14. Some of the most prominent symptoms in schizophrenia are persistent15 delusions16（妄想，错觉） , hallucinations（幻觉） and cognitive17 problems. Bipolar disorder (or manic-depressive illness) is characterized by episodes of severe mood problems including mania18（狂躁） and depression. Despite the availability of treatments, these illnesses are usually chronic19, often leads to prolonged disability and personal suffering. Family history is a strong risk factor for both disorders. The new findings are further evidence for the general assumption that dozens of genes, along with environmental factors, contribute to disease risk.
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