Study Discovers Novel Risk Genes For Bipolar Disorder

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Bipolar disorder, also known as manic depression characterized by mood swings between manic and hypomanic states (elevated and depressive states), is a common mental disorder with a lifetime prevalence of one percent.

The condition is accompanied by symptoms such as been abnormally energetic, happy or irritable, making poor decisions, sleeplessness, poor eye contact, suicidal thought, self harm, anxiety disorder and substance use disorder.

While the epidemiological studies of the condition have shown that genetic components contribute to the development of bipolar disorder, many genome-wide association studies (GWASs) has identified a limited number of susceptibility genes for the condition, most of which are still unidentified.

Collaborative research under the guidance of the principle investigators from Fujita Health University and RIKEN in Japan, has led to the discovery of a novel risk gene, FADS1 and FADS2, for bipolar disorder. The identification was made possible through GWAS performed using samples collected from 2,964 cases and 61,887 comparison subjects in Japan, according to Science Daily.

The function of the gene is well established and includes metabolism of lipids including blood lipids, a cholesterol and triglyceride and omega 3/6 polyunsaturated fatty acids (PUFA). However, previous epidemiological surveys revealed that prevalence of hyperglycemia or metabolic syndrome in persons with bipolar disorder was relatively higher than that of the general population. This made the researcher to conclude that lipid abnormality may be involved in bipolar disorder pathophysiology.

The study authors further conducted a meta-analysis between their samples and results from the publicly available BD GWAS database (Psychiatric GWAS Consortium) so as to maximize the size of their sample. They were able to identify an additional novel gene for bipolar disorder, NFIX and also supported three previously implicated genes, ODZ4, MAD1L1 and TRANK1.

The massive size of the sample analyzed in the study is said to be one of the largest, most especially as samples were collected from Asian populations. But due to the extremely small effect size of the bipolar disorder risk (odds ratio 1.2), Prof. Nakao Iwata explains that a large number of risk genes are still unidentified. Thus, further study is required for the identification of more bipolar disorder risk genes, according to Medical Express.

In addition, Iwata noted that the findings of the study cannot yet be applied in a clinical setting. Based on the relationship of these genes with Bipolar disorder, in terms of their function, the researchers believe that new therapeutic strategies should be developed including the investigation and development of new medications for the condition.