The gene that likely makes people left-handed mayslightly raise the risk of developing psychotic mental illnesses, according to an internationalstudy.

Led by the Wellcome Trust for Human Geneticsat the Universityof Oxford,the studyinvolves a team of 40 scientists from 20 research centres across the world, and was published online Tuesday in the scientific journal Molecular Psychiatry.

"This is the first potential genetic influence on human handedness to be identified, and the first putative genetic effect on variability in human brain asymmetry," said an abstract onthe study.

The scientists said that little is known about the geneLRRTM1, but they suspect that it modifies symmetry in the human brain. Asymmetry is important, since the left side of the brain usually controls speech and language and the right side controls emotion. With left-handers this pattern is often reversed.

The researchers suspect that the same gene might slightly increase the risk of developing schizophrenia — a disorder of the brainthat often results in impaired perception and thought that affects roughly one per cent of adults worldwide.

Like left-handers, people with schizophrenia also often have unusual patterns of brain asymmetry.

Thestudy leader, Dr. Clyde Francks, said in a statement, "People really should not be concerned by this result. There are many factors which make individuals more likely to develop schizophrenia and the vast majority of left-handers will never develop a problem. We don’t yet know the precise role of this gene."

Some of the study's researchers plan to further investigate the roles of LRRTM1 in the developing brain, and to find other genes with whichit interacts.

"We hope this study’s findings will help us to understand the development of asymmetry in the brain.Asymmetry is a fundamental feature of the human brain that is disrupted in many psychiatric conditions," added Dr. Francks.

Roughly10 per cent of peopleare left-handed. Last year, Australian researchers suggested that left-handers can thinkmore quicklywhen it comes to tasks such as playing computer games or playing sports.