A global team of researchers have identified 30 areas of the human genome where variations in genetic code can increase the risk of developing bipolar disorder.

 The study, conducted by the Bipolar Disorder Workgroup of the Psychiatric Genomics Consortium, compared genetic variations in over 29,000 people with bipolar disorder, including more than 4,000 from the Bipolar Disorder Research Network (BDRN), and 160,000 people who do not have the condition.

This involved the systematic analysis of hundreds of thousands of genetic markers in order to find chromosomal regions associated with risk of bipolar disorder.

Genetic differences between bipolar 1 and bipolar 2

Dr Arianna Di Florio, Clinical Senior Lecturer at Cardiff University’s MRC Centre for Neuropsychiatric Genetics and Genomics said, “Our analyses pointed to genes relevant to the nervous, immune and metabolic systems.

“We also found differences in the genetic makeup between individuals with bipolar I disorder, who have a history of severe manic episodes, and those with bipolar II disorder, who don’t experience such severe episodes.”

Further analyses found that bipolar I disorder shares a strong genetic link with schizophrenia, whereas bipolar II disorder is more strongly linked with major depressive disorder.

These findings will pave the way for more intensive studies of the implicated genetic regions and potentially identify specific genes which are involved in the development of bipolar disorder.

Dr Di Florio added, “Ultimately, we hope that our investigations will lead to a better understanding of the molecular mechanisms underlying bipolar disorder.

Better treatments and outcomes for bipolar patients

“This should lead to the development of new, more effective and better-targeted treatments and will hopefully result in better outcomes for people affected by this severe mental illness.”

Professor Lisa Jones, principal investigator at BDRN and the Mood Disorders Research Group at University of Worcester said, “This was a truly global effort, involving researchers from more than 200 institutions and data from 32 cohorts across Europe, North America and Australia.

“These findings would not have been possible without so many people giving their time to take part in research and donate biological samples, so on behalf of the workgroup I’d like to thank all those who contributed to this work.”

The paper, Genome-wide association study identifies 30 loci associated with Bipolar Disorder, is published in Nature Genetics.