UK researchers have identified a genetic variation associated with an increased risk of schizophrenia in people with a strong family history of the condition. The team, based at Edinburgh University, discovered that individuals who inherit a particular version of the neuregulin (NRG1) gene have nearly three times the risk of developing psychotic symptoms. The findings, published in the journal Nature Neuroscience, build upon earlier work implicating the gene in schizophrenia.
The scientists followed 200 people aged between 16-25 for ten years, a project known as the 'Edinburgh High Risk Study'. All had two or more relatives with the schizophrenia, which meant they were at increased risk of developing symptoms of the condition. The team carried out brain scans, psychological tests, interviews and genetic tests, to find out why some people with a family history of the disorder go on to develop the disorder while others do not. They discovered that 100 per cent of those who had the neuregulin gene variant developed psychotic symptoms, compared to 40 per cent of all the participants, a result described as 'highly statistically significant'.
The researchers also discovered that individuals with the variant were more likely to show abnormal brain activity in the frontal and temporal regions, two areas thought to be affected in schizophrenia. The variation affects the neuregulin gene promoter - its 'on/off switch' - rather than the part that encodes the protein, which is thought to be involved in brain development. Lead author Jeremy Hall called the results 'a breakthrough', while team leader Professor Eve Johnstone praised the 'altrusim and courage' of the study participants.
Dr Hall commented that 'these major mental illnesses have really been for a very long time a big black box in terms of what is causing them and treatments have not advanced a lot over the last 50 years', adding 'you have to understand more about what causes diseases before you can start designing treatments for it'. He said that understanding how a gene might alter brain function and cause symptoms might represent a target for future treatments. Dr James MacCabe, of Kings College London, said: 'Over the past ten years there have been about 10 possible genes identified, and neuregulin is s very promising gene'.
Majorie Wallace, chief executive of the UK mental health charity Sane, said that many hopes of finding a gene for schizophrenia had ended in a cul-de-sac. 'If this latest research were to prove a breakthrough and lead to understanding what causes schizophrenia, we could at last find more effective treatments and potential cures, transforming the future for the one in 100 who suffer from this devastating condition', she told BBC News Online.