Schizophrenia is a mental disorder marked by the sufferer's inability to distinguish what is real and is characterized by confused thinking, false beliefs, auditory hallucinations and abnormal social behavior.
Although scientists have found a link between schizophrenia and genetics and other factors, much about the condition remains a mystery. Experts, for instance, are not completely sure as to what causes the illness. The condition also manifests variably in people who have it. A new research, however, could pave way to a better understanding of the disease and hopefully lead to improved diagnoses and more effective treatment for the disorder.
A group of researchers from the Washington University School of Medicine in St. Louis, Missouri have found that the debilitating psychotic disorder is not actually a single disease. Findings of their study suggest that schizophrenia is instead linked to eight distinct genetic disorders each with its own symptoms.
For the new study published in The American Journal of Psychiatry on Sept. 15, Robert Cloninger, a psychiatric geneticist from the Washington University, St. Louis, and colleagues looked at exact DNA variation in subjects with or without schizophrenia and matched this to symptoms found in individual patients.
By analyzing almost 700,000 sites within the genome where there is a variation in a single unit of DNA, otherwise known as single nucleotide polymorphism, or SNP, in 4,200 schizophrenia patients and 3,800 individuals without the condition, the researchers learned how genetic variations interact with each other to produce the mental disorder.
Cloninger and colleagues also came up with a method to determine groups of interacting gene clusters and match these with sets of symptoms and the odds of patients developing the disease. Individuals with a particular gene clusters, for instance, had 70 percent increased odds of developing a form of schizophrenia.
"What we've done here, after a decade of frustration in the field of psychiatric genetics, is identify the way genes interact with each other, how the 'orchestra' is either harmonious and leads to health, or disorganized in ways that lead to distinct classes of schizophrenia," Cloninger said.
By organizing the genetic variations and the symptoms of the patients into groups, the researchers were able to see that certain clusters of SNPs acted together and resulted in distinct types of symptoms allowing them to identify particular gene clusters that contribute to eight different forms of schizophrenia.
"Schizophrenia is a group of heritable disorders caused by a moderate number of separate genotypic networks associated with several distinct clinical syndromes," the researchers wrote.