Three studies conducted by institutes of health shows that the combination of hundreds of small genetic variations could be the cause of at least one-third of the risk of schizophrenia.

The three studies conducted by the U.S. National Institute of Mental Health, the company deCODE genetics and the consortium on the molecular genetics of schizophrenia have focused on 8014 cases of schizophrenia and 19,090 people not suffering from it.

A specific area of chromosome 6 is highlighted. This area covers the genes related to immunity and infection, and also genes involved in controlling the activation or deactivation of genes.

The environmental factors play a part in the risk of schizophrenia, the attack of this zone of chromosome explains it. A child whose mother caught flu during pregnancy have a higher risk of developing this disease.

“All 450 variations in the area of chromosome 6 and in an area of chromosome 22 lead to at least one-third the risk of developing schizophrenia”, said Shaun Purcell of the International Consortium on schizophrenia.

Another consortium dedicated to genetic research on schizophrenia, has also highlighted the role of variations on chromosomes 11 and 18 in the defect concentration and memory.