Previously there was no evidence to suspect chromosome 6 region of the human genome as a risk factor for schizophrenia though it was already known that nearly 80 percent of risk for schizophrenia account due to genetics.

That makes it hard to tease out, in a statistically significant way, any of these schizophrenia-associated genes, said Dr. Douglas Levinson, director of the Program on the Genetics of Brain Function at Stanford University School of Medicine.

To prove the theory, Levinson and colleagues examined DNA data from three studies that included 27,000 people, 8,000 schizophrenia patients and 19,000 people without the disease.

The study restricted participants to those of European ancestry in order to exclude numerous non-disease-related genetic differences that would have to be separated if participants had different ancestries.

Latest genetic technologies were used to search for tiny genetic variations called single base-pair polymorphisms (SNPs). They found that the largest genetic differences were found on chromosome 6 between people with schizophrenia and those without the disease.

The papers present the first highly significant findings of gene regions associated with schizophrenia risk, Levinson said.

He added that these findings show that our genetic methods are working and that the genetic underpinnings of schizophrenia can be understood. Similar methods have produced critical new discoveries in many other common diseases, once very large numbers of people could be studied. Now we see that the same approach works for psychiatric disorders like schizophrenia.