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28-09-2011 | Psychology | Article

Genetic link between schizophrenia and bipolar disorder confirmed

Abstract

Free abstract

MedWire News: Researchers from the Psychiatric Genome-Wide Association Study (GWAS) Consortium have identified genetic variants that are associated with an increased risk for both schizophrenia and bipolar disorder.

In two GWASs, published in the journal Nature Genetics, investigators provide evidence linking 11 genomic regions to the development of these mental health conditions, of which six have not previously been identified. A number of the identified genetic variations contribute to both bipolar disorder and schizophrenia.

"Until recently, psychiatric research has understood the genetic basis of mental illness only very poorly," said Shaun Purcell (Mount Sinai School of Medicine, New York, USA), co-author on the schizophrenia study.

"Our research has helped us begin to elucidate the genetic structure of bipolar disorder and schizophrenia, and will, we hope, provide a new foundation to build upon in improving treatments and the quality of life of these patients."

In the first study, Pablo Gejman (NorthShore University HealthSystem, Evanston, Illinois, USA) and colleagues studied genetic data on 17,836 patients with schizophrenia and 33,859 individuals without the condition.

They identified seven loci (6p21.32-p22.1, 18q21.2, 1p21.3, 2q32.3, 8p23.2, 8q21.3, and 10q24.32-q24.33) that are significantly associated with schizophrenia risk. Of these, the latter five loci have not been previously implicated in the risk for the condition.

The strongest association was found for a single nucleotide polymorphism (SNP), rs1625579, in the MIR137 gene, a known regulator of neuronal development.

In the second study, Pamela Sklar (Mount Sinai School of Medicine) and colleagues, analysed genetic data on 11,974 patients with bipolar disorder and 51,792 mentally healthy individuals.

They found evidence that an intronic variant in the ODZ4 gene is significantly associated with bipolar disorder risk, and confirmed an association with SNPs in the CACNA1C gene.

A combined analysis of both bipolar disorder and schizophrenia samples indicated that SNPs in CACNA1C (rs4765905), ANK3 (rs10994359), and the ITIH3-ITIH4 region (rs2239547), were significantly associated with both disorders.

"Schizophrenia and bipolar disorder are debilitating illnesses affecting millions of people around the world, and existing therapies for these people are ineffective as long-term options," said Sklar.

"We have been hard at work trying to determine genetic risk for these diseases so that we can intervene earlier and develop new therapies with which to treat them. Through this research, we are an important step closer to making that possible."

By Mark Cowen

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