New genes that confirm that the immune system may play a role in the development of Schizophrenia have been identified by an international study led by researchers at the University of California-Los Angeles and nearly 50 institutions worldwide.
The researchers say that they have also identified genetic anomalies that disrupt the cellular pathways involved in brain development, memory and cognition, all markers of schizophrenia.
Roel Ophoff, the co-lead author and an assistant professor at the Center for Neurobehavioral Genetics at the UCLA Semel Institute for Neuroscience and Human Behavior, has revealed that he and his collaborators performed a genome-wide scan of 2,663 people diagnosed with schizophrenia, and 13,498 controls from eight European locations.
He said that they were looking for single nucleotide polymorphisms (SNP), genetic variations that are commonly present in the general population but more often present in those suffering from the disorder.
In total, nearly 314,000 SNPs were included in the analysis, he added.
Ophoff said that their study revealed significant associations with genetic markers on the Major Histocompatibility Complex (MHC), a group of genes that controls several aspects of the immune response.
He further said that the team also found additional variations in two other genes, called NRGN and TCF4, pointing to perturbation of pathways involved in brain development, memory and cognition.
"This is another step forward in understanding the biological basis of this disorder, one that robs people of their lives," Nature magazine quoted Ophoff, who holds a joint appointment at the University of Utrecht, The Netherlands, as saying.
"It also shows the importance of worldwide collaborations for the study of schizophrenia genetics, because it allows us to do very large numbers of scans," he added.
Ophoff said that the findings were significant yet not without challenge since the study aimed at the "common variants" in the human genome.
"In other words, these are not rare mutations present in only a few individuals, but these genetic variants are abundantly present in the population. Anybody could carry this variant, but that doesn't mean they will necessarily develop the disease. Yet, when you look at the population at large, these variants are more often present in patients than in healthy control subjects," he said.
And that's important in developing new techniques to thwart the disease, he reckons.
"Knowing these specific genes are involved in the pathway leading to schizophrenia provides unique clues as to which molecular mechanisms are involved," he said.
While the association between schizophrenia and the immune system has long been suspected, the evidence for it has been mostly circumstantial to date.
And impaired cognitive and memory functions are increasingly being recognized as core features of schizophrenia, which are poorly addressed by current medications.
"The three common genetic variants we describe, then, which we feel predisposes certain individuals to schizophrenia, have the potential to be translated into targets for the development of new and novel medications," Ophoff said.