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.

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