A team of international researchers has discovered two new genes connected to bipolar disorder.

A study that will be published in the Nature Communications journal analyzed genetic material from about 24,000 people, revealing five risk regions in human DNA associated with the disease.

Two of those genes ADCY2 on chromosome five and MIR2113-POU3F2 on chromosome six are new discoveries.

Researchers are especially interested in the ADCY2 gene, which codes an enzyme involved in conducting signals to nerve cells. Scientists have previously observed that signal transfers in certain regions of the brain are impaired in people with bipolar disorder.

For the study, researchers obtained new genetic data from 2,266 people with bipolar disorder, and 5,028 people from a control group. When that information was merged with existing data sets from the Institute of Human Genetics, DNA from a total of 9,747 patients was compared to that of 14,278 healthy people.

The investigation of the genetic foundations of bipolar disorder on this scale is unique worldwide to date," one of the researchers, Marcella Rietschel of the Central Institute of Mental Health of Mannheim, Germany, said in a news release.

Researchers said the study is unparalleled because it involved an unprecedented number of patients from around the world.

About one per cent of the global population suffers from bipolar disorder, characterized by intense mood swings. Patients go from experiencing extreme euphoria and hyperactivity or manic phases to extreme depression. Scientists have been trying to understand what role genetics, in addition to a patients environment and other factors, play in the development of the disease.

Markus M. Nthen, director of the Institute of Human Genetics at the University of Bonn Hospital, said that many different genes are evidently involved and these genes work together with environmental factors in a complex way."

Researchers say identifying genes related to bipolar disorder is like looking for a needle in a haystack. Differences between the DNA of people with the disease and healthy individuals can only be statistically confirmed when a large number of samples is involved, as was the case in this study.

Read more:

'Unparalleled' study discovers new genes connected to bipolar disorder