Schizophrenia may be a cluster of disorders

Post Reply New Topic

http://news.wustl.edu/news/Pages/27358.aspx

New research shows that schizophrenia isn?t a single disease but a group of eight genetically distinct disorders, each with its own set of symptoms. The finding could be a first step toward improved diagnosis and treatment for the debilitating psychiatric illness.

The research at Washington University School of Medicine in St. Louis is reported online Sept. 15 in The American Journal of Psychiatry.

About 80 percent of the risk for schizophrenia is known to be inherited, but scientists have struggled to identify specific genes for the condition. Now, in a novel approach analyzing genetic influences on more than 4,000 people with schizophrenia, the research team has identified distinct gene clusters that contribute to eight different classes of schizophrenia.

?Genes don?t operate by themselves,? said C. Robert Cloninger, MD, PhD, one of the study?s senior investigators. ?They function in concert much like an orchestra, and to understand how they?re working, you have to know not just who the members of the orchestra are but how they interact.?

Cloninger, the Wallace Renard Professor of Psychiatry and Genetics, and his colleagues matched precise DNA variations in people with and without schizophrenia to symptoms in individual patients. In all, the researchers analyzed 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.

In some patients with hallucinations or delusions, for example, the researchers matched distinct genetic features to patients? symptoms, demonstrating that specific genetic variations interacted to create a 95 percent certainty of schizophrenia. In another group, they found that disorganized speech and behavior were specifically associated with a set of DNA variations that carried a 100 percent risk 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.

Although individual genes have only weak and inconsistent associations with schizophrenia, groups of interacting gene clusters create an extremely high and consistent risk of illness, on the order of 70 to 100 percent. That makes it almost impossible for people with those genetic variations to avoid the condition. In all, the researchers identified 42 clusters of genetic variations that dramatically increased the risk of schizophrenia.


here's the rest with photos and videos>>> http://news.wustl.edu/news/Pages/27358.aspx

Not surprising. There's an obvious reason why certain people experience certain types of psychotic behaviors and not others. But while I'm glad that genetics research is helping unravel nosological debates in psychiatry, I hope it doesn't end up completely changing things. Like, I hope we keep "schizophrenia" as we know it, rather than have, say, eight different diagnostic labels for the eight different genetic lineages. I'd rather the genetics information help with selection of medications and creating an actual diagnostic test.