Genetically, Schizophrenia Has Eight Forms

Schizophrenia has many faces. Researchers have long known that the risk for schizophrenia is inherited. In new findings published online Sept 15 in The American Journal of Psychiatry, senior investigator C. Robert Cloninger, MD, PhD, of the Washington University School of Medicine in St. Louis, MO, said his team identified distinct gene clusters that contribute to 8 different classes of the disease.

In an interview on the school’s website, Cloninger said the team analyzed DNA variations in 4,200 people with schizophrenia. Though most genetic research into the causes of the illness have focused on searching for an individual genes that might cause schizophrenia, the St. Louis team found it appears to be clusters of genes that put people at highest risk.

These clusters are directly associated with patients’ symptoms. For instance, patients afflicted with hallucinations or delusions had different genetic features than patients with disorganized speech and behavior, Cloninger said.

By analyzing patients’ symptoms and seeing which patients had which gene clusters, the team came up with 8 distinct types of schizophrenia. The findings could open new pathways for drug research, with new products tailored for each of these new genetically based subtypes of the illness.

Cloninger also believes the work shows that the concept of gene clusters working in concert to cause a disease could lead researchers in other fields to rethink their approach to looking for ways to treat complex diseases.

“People have been looking at genes to get a better handle on heart disease, hypertension and diabetes, and it’s been a real disappointment,” he said. “Most of the variability in the severity of disease has not been explained, but we were able to find that different sets of genetic variations were leading to distinct clinical syndromes. So I think this really could change the way people approach understanding the causes of complex diseases.”

The study was funded by the US National institute of Mental Health, the Spanish Ministry of Science and Technology, and others.