A group of researchers from Spain and the U.S. have found that schizophrenia is actually a group of eight genetically different types of diseases, each of which presents its own set of symptoms.
Scientists from the universities of Granada (Spain) and Washington in St. Louis have published their research in the American Journal of Psychiatry.
Experts believe this could be an important first step towards a better diagnosis and treatment of this disease, which affects approximately one percent of the world’s population.
Researchers were aware that approximately 80 percent of the risk of suffering from schizophrenia was hereditary, although scientists have struggled for years to identify which specific genes lead to it.
The new study included 4196 patients diagnosed with schizophrenia and 3200 healthy patients. Experts were, for the first time, able to identify the different genes networks that contribute to the existence of eight different types of schizophrenia.
“Genes do not operate on their own, in an isolated manner,” said Igor Zwir, Ph.D., a researcher at the university of Granada and co-author of his article, pointed out, “they rather work with each other as an orchestra.
“To understand how they work, we must not just know what each member of this orchestra is like, but also how they interact with each other”.
“What we did with this research, after a decade of frustration in the field of psychiatric genetics, is identify the manner in which the genes interact with each other, in an orchestrated manner in the case of healthy patients, or disorganized, as happens in the cases that lead to the different types of schizophrenia”, say the investigators.
Thus, in some patients with hallucinations or delirium, for instance, researchers agree that there are different networks of genes related to their respective symptoms, which demonstrates that specific genetic variations interact with each other.
This genetic analysis leads to 95 percent certainty in predicting the onset of schizophrenia.
In another group, they found that incongruent speech and disorganized behavior are specifically associated with a DNA variations network that leads to a 100 percent risk of suffering schizophrenia.
Researchers divided the patients according to the type and seriousness of positive symptoms (such as different types of hallucinations or deliriums), or negative symptoms (such as lack of initiative, troubles in organizing thoughts, or lack of connection between emotion and thought).
Scientists also classified the profiles of these symptoms into eight qualitative types of different diseases according to the underlying genetic conditions.
“In the past, scientists had searched for associations between individual genes and schizophrenia — researchers point out. What was lacking was the idea that these genes do not act independently, but that they work as a group instead, to disturb the structure and the functions of the brain, thus causing the disease.”
Although individual genes only present weak, inconsistent associations with schizophrenia, the interaction networks of gene groups pose a high risk of suffering from the disease, between 70 and 100 percent, “which makes it almost impossible that individuals with those genetic variation networks will avoid schizophrenia”
Researchers found a total of 42 genes groups that influenced in a variety of ways the risk of suffering schizophrenia.
They also replicated their finds in two independent samples of individuals with schizophrenia, an index that these networks are a valid path for the exploration and improvement of the diagnosis and treatment of this disease.
“The identification of gene networks and their related symptoms in individual patients may allow clinicians to develop localized treatment for the specific paths that cause schizophrenia,” Zwir said.
Source: University of Granada/EurekAlert