Genomic Analysis: Eight Distinct Types of Schizophrenia

From Psychiatric News Alert. Schizophrenia appears to be “heterogenous”—that is, comprising a group of related disorders each of which present with distinct clinical syndromes; and those syndromes now appear to be associated with eight separate networks of genetic mutations.

That’s the finding from a remarkable genetic analysis titled “Uncovering the Hidden Risk Architecture of the Schizophrenias: Confirmation in Three Independent Genome-Wide Association Studies,” appearing in AJP in Advance.

Schizophrenia (Sepultura album)

Schizophrenia (Sepultura album) (Photo credit: Wikipedia)

In a large genome-wide association study of cases with schizophrenia and controls, researchers with the Molecular Genetics of Schizophrenia Consortium (an international group of researchers) examined single nucleotide polymorphisms (SNPs) that grouped or clustered together and assessed the risk for schizophrenia by comparing the cases and noncases. They then looked at relationships between the SNP clusters and various ways that patients present symptomatically across three separate studies.

The authors identified 42 SNP sets associated with a 70 percent or greater risk of schizophrenia and confirmed 34 (81 percent) or more with similar high risk of schizophrenia in two independent samples. These SNP sets or genotypic networks were linked to the different ways that patients present with schizophrenia, yielding eight distinct clinical syndromes varying in symptoms and severity.

“We found that some genetic pathways increasing susceptibility involved deficient control of healthy brain development, and other pathways involved increased susceptibility to brain injury and toxicity,”

Claude Robert Cloninger, M.D., a study coauthor and a professor of psychiatry at Washington University School of Medicine, told Psychiatric News. “Regulation of the plasticity of glutamate receptors was important in some classes of schizophrenia and not others.

A Single Nucleotide Polymorphism is a change o...

“The main take home message is that there are many pathways to schizophrenia, which converge on eight classes of the disorder,” he said.

Full coverage of this study will appear in a future issue of Psychiatric News. For more information on psychiatric genetics, see the Psychiatric News article, “Revolution in Psychiatric Genetics Rapidly Gains Steam.

Unlocking the Secrets of Schizophrenia

By Dina Al Qassar, NAMI Intern

Schizophrenia continues to confound the minds of scientists and researchers alike. Affecting 1% of the human population, the culprit behind this illness is still unknown. There has been research investigating the causes of schizophrenia, and although scientists have known that it runs in families there isn’t any evidence indicating that the causes are purely genetic. The belief is that both genetic and environmental factors play equal parts in the development of schizophrenia.

There have been speculations about the causes, including but not limited to: prenatal factors (viral infections during the pregnancy, malnourishment, stress); environment factors (emotional, physical, or sexual abuse); abnormalities in the brain structure (irregularities in the size of the prefrontal and temporal lobes), neurotransmitter imbalances (high levels of dopamine and low levels of serotonin), etc… yet there aren’t any definite links between a single factor and the disease.

Due to the unique nature of schizophrenia it is very hard to find the causes of the illness. Recently however, a significant pattern emerged between schizophrenia and inheritance that was revealed by looking at the way schizophrenia is more prevalent in some families; this spurred the genetic investigation of the matter.

Schizophrenia - schizophrénie

Schizophrenia – schizophrénie (Photo credit:

According to Dr. Francis Collins, the director of the National Institutes of Health (NIH), in his blog post from Jan. 28, “Exploring the Complex Genetics of Schizophrenia,” new developments in DNA sequences technology have allowed scientists to look at the “actual DNA sequence of the protein-coding region of the entire genome for thousands of individuals with schizophrenia.” This would then give further insight into the nature of the genetic variations and if there is a direct relationship between these genetic mutations and the illness.

For the rest of this article CLICK HERE to visit the NAMI National Site.

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