An international team of researchers has found that the cause of schizophrenia is even more complex than already believed, with rare gene mutations contributing to the disorder. In two studies published in the journal Nature, they show that schizophrenia arises from the combined effects of many genes.
Blood DNA taken from 6,948 people in Bulgaria and Sweden was catalogued. This included patients diagnosed with schizophrenia, their parents and healthy controls. Scientists were able to pinpoint the sites of gene mutations and identify patterns that reveal clues about the biology underlying schizophrenia. Rather than finding only a few "faulty" genes, the two studies determine that the genetic basis of schizophrenia is tremendously complex. The data confirms that it is a very large number of rare genetic mutations that contribute to risk of developing the disorder.
Schizophrenia is a chronic, often debilitating mental illness that affects 1% of people at some time in their lives. Symptoms include persistent hallucinations, delusions and paranoia. The exact cause of the disorder remains unknown, but is considered to result from a complex interplay of a person's genes and their environment.
Many studies have shown that schizophrenia runs in families and so genes are undoubtedly a factor. A tenth of people with schizophrenia have a parent with the condition. But, despite its high heritability, a large number of individuals with schizophrenia do not have a family history of the disease. The search for a "schizophrenia gene", though popular, has not proved fruitful. This research sheds light on how genetics plays a role in cases which have not been inherited.
These two new studies are the result of the largest genetic study of its kind with scientists hailing from nine different institutions including Cardiff University and the Broad Institute of MIT and Harvard. The clinical and genetic information gathered on more than 3,000 affected individuals has produced the world's largest database on schizophrenia.
