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Study reveals genetic secrets behind schizophrenia and bipolar disorder

Knowing of a genetic predisposition to schizophrenia could help a person avoid environmental risk factors that aggravate it. Flickr/notsogoodphotography

One of the world’s largest schizophrenia studies ever has pinpointed five new genetic blips linked to the condition, paving the way for new drugs and management strategies, researchers said.

Schizophrenia affects 1 in 100 people, commonly causing delusions, hallucinations and an increased risk of suicide.

Scientists knew that a family history of schizophrenia could predispose subsequent generations to the condition but it was not clear exactly which parts of the human genome were linked to an increased risk.

To find out, the Schizophrenia Psychiatric Genome-Wide Association Study Consortium, which included 190 researchers from 135 institutions worldwide, analysed genetic data from 21,856 individuals and checked their conclusions by studying an additional 29,839 people.

In a paper titled “Genome-wide association study identifies five new schizophrenia loci” published today in the journal Nature Genetics, the researchers said their study found five new genetic variations associated with schizophrenia. They also confirmed several other genetic blips that previous studies had suggested could contribute to the disorder.

Unlocking the genetic causes of schizophrenia could one day help people manage or mitigate its effects, said Professor Bryan Mowry from the Queensland Brain Institute, based at the University of Queensland.

“If your genetic profile suggests you have a predisposition towards developing schizophrenia, it will be particularly important for you to avoid known environmental risk factors – such as smoking cannabis,” said Professor Mowry, who oversaw the Australian contribution to the study.

“Interactions between genetic risk factors and the impact of the environment are crucial to the understanding of the neurophysiological mechanisms that influence the daily life of the sufferers,” said Professor Assen Jablensky from the University of Western Australia’s Centre for Clinical Research in Neuropsychiatry, which was involved in the study.

“The results, pointing to several novel genetic factors contributing to the disease, highlight especially the role of microRNAs, small molecules that regulate critical genetic pathways in the brain,” he said.

“This will eventually lead to novel targets for the pharmacological treatment of the disorder, much more focused on specific brain mechanisms than the present day anti-psychotic medications.”

“Ground-breaking” bipolar research

A subgroup of the same consortium that conducted the schizophrenia study also researched 11,974 bipolar disorder cases and 51,792 controls in an effort to better understand its causes.

Bipolar disorder, which can run in families, is marked by severe mood swings.

In a second paper, titled “Large-scale genome-wide association analysis of bipolar disorder identifies a new susceptibility locus near ODZ4” and published today in Nature Genetics, the researchers linked two particular genes to bipolar.

Professor Philip Mitchell, Head of the School of Psychiatry at the University of New South Wales (UNSW), and Director of the Bipolar Disorders Clinic at Black Dog Institute described the bipolar study as “ground-breaking research.”

“The research confirmed that a gene for a component of the calcium channel (CACNA1C) is involved in causing bipolar disorder and also identified a novel gene involved in cell surface signaling (ODZ4).”

Both findings could lead to new treatments, he said.

“Moreover, when both the bipolar disorder and schizophrenia groups were combined, there was evidence that CACNA1C was involved in both conditions – verifying a number of research strands indicating some genetic overlap between these two disorders.”

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