Via io9: ‘New research published in the American Journal of Psychiatry suggests that schizophrenia is not a single disease, but rather a group of eight genetically distinct disorders, each of them with its own set of symptoms. The finding could result in improved diagnosis and treatment, while also shedding light on how genes work together to cause complex disorders.
…Complex diseases like schizophrenia may be influenced by hundreds or thousands of genetic variants that interact with one another in complicated and dynamic ways, leading to what scientists call “multifaceted genetic architectures.” Now, thanks to the work of investigators at the Washington University School of Medicine in St. Louis, the genetic architecture for schizophrenia is starting to take shape.
…So, for example, hallucinations and delusions were associated with one set of DNA variations, that carried a 95% risk of schizophrenia. Another symptom, disorganized speech and behavior, was found to carry a 100% risk with another set of DNA.
…When it comes to schizophrenia and other complex conditions, individual genes have only a weak and inconsistent association (which is why it’s often silly to look for single-gene factors). But groups of interacting gene clusters create an extremely high and consistent risk of illness — in this case, on the order of 70% to 100%. It’s nearly impossible for people with these precise genetic variations to avoid the condition. In all, the researchers found no less than 42 clusters of genetic variations that significantly increase the risk of schizophrenia. “…What was missing was the idea that these genes don’t act independently. They work in concert to disrupt the brain’s structure and function, and that results in the illness.” ‘
As a clinical psychiatrist focusing on patients with this condition, this is a confirmation of my certainty about the heterogeneity of schizophrenia. When you try to do research on characteristics, causes, or treatment approaches to a diverse group of people sharing little beyond a diagnosis, it is no wonder that no strong conclusions emerge.