A research team led by Dr. C. Robert Cloninger has shown that schizophrenia is caused by eight distinct genetic disorders, each disorder presenting with its own specific set of symptoms.
Dr. Cloninger is a Professor of Psychiatry and Genetics at the Washington University in St. Louis, MO and has been long interested in the genetic components of schizophrenia. The research team’s findings could influence the way doctors diagnose and elaborate treatment strategies for the disease.
Generally governed by delusions, hallucinations, abnormal thoughts or cognitive problems, schizophrenia is a disease much likelier to develop in subjects whose family histories also contain affected relatives. The illness occurs in 1% of the general population, but in the case of individuals with first degree relatives suffering from schizophrenia, the risk of also getting the disease is 10%.
Dr. Cloninger began his study after he inspected the work of another research team that had identified 83 new genes that were linked to schizophrenia. He then analyzed the genomes of 4,200 of his patients suffering from the disorder, and additionally, the genomes of 3,800 people not affected by the disorder. After inspecting over 700,00 areas in the genome where he had expected a variation to occur in a DNA unit (this variation is called SNP-single nucleotide polymorphism), he then compared those variations with the control group.
The team was able to identify the differences between the SNP’s of schizophrenic patients and healthy controls. It seems that different genetic variations interact with each other in producing the symptoms of schizophrenia. According to them, there are gene clusters connected specifically to each of the eight types of schizophrenia. For instance, the team isolated one gene cluster that was associated with a 95% risk of schizophrenia, as well as delusions and hallucinations.
Aside from their own findings, the researchers also analyzed two other databases of sick patients and saw if their results matched up to prior findings.
According to Dr. Cloninger’s statement, the research team has finally identified how genes interact with each other to orchestrate harmoniously and create health, or non-harmoniously and lead to distinct classes of the illness. This comes after more than a decade marked with frustration in the field of psychiatric genetics.
When the genes identified by the research team are found individually in sequences, they connect inconsistently with the disorder, but when they work as clusters, they create a 70-100% risk of leading to schizophrenia.
The question is if scientists will now be able to target specific pathways identified by Dr. Cloninger’s team in the treatment of the disorder.