The debilitating psychiatric illness schizophrenia is not a single disease but a group of eight genetically distinct disorders - each with its own set of symptoms, new research indicates.
In a novel approach analysing genetic influences on more than 4,000 people with schizophrenia, the team from Washington University has identified distinct gene clusters that contribute to eight different classes of schizophrenia.
The finding could be a first step toward improved diagnosis and treatment for the brain disease.
"We has identified the way genes interact with each other, how the 'gene orchestra' is either harmonious and leads to health or disorganised in ways that lead to distinct classes of schizophrenia," explained C. Robert Cloninger, one of the study's senior investigators from the Washington University's school of medicine.
Cloninger and his colleague Igor Zwir matched precise DNA variations in people with and without schizophrenia to symptoms in individual patients.
In all, researchers analysed nearly 700,000 sites within the genome where a single unit of DNA is changed - often referred to as a single nucleotide polymorphism (SNP).
They looked at SNPs in 4,200 people with schizophrenia and 3,800 healthy controls, learning how individual genetic variations interacted with each other to produce the illness.
Researchers finally identified 42 clusters of genetic variations that dramatically increased the risk of schizophrenia.
"It may be possible to use the same approach to better understand how genes work together to cause other common but complex disorders," Cloninger concluded.
The research was reported online in The American Journal of Psychiatry.