Genomics yields biological and phenotypic insights into bipolar disorder

Area of Science:

• Psychiatry
• Genetics
• Neuroscience

Background:

• Bipolar disorder significantly contributes to the global disease burden.
• Despite high heritability (60-80%), its genetic determinants are largely unknown.
• Previous genetic studies have identified limited loci associated with bipolar disorder.

Purpose of the Study:

• To identify novel genetic loci associated with bipolar disorder across diverse ancestries.
• To investigate the role of both common and rare genetic variants in bipolar disorder etiology.
• To explore differences in genetic architecture based on patient ascertainment and subtype.

Main Methods:

• A large-scale genome-wide association study (GWAS) meta-analysis was conducted.
• Data included 158,036 cases and 2.8 million controls from European, East Asian, African American, and Latino ancestries.
• Fine-mapping and variant-to-gene mapping approaches were integrated.

Main Results:

• Identified 298 genome-wide significant loci, a fourfold increase over previous findings.
• Discovered an ancestry-specific association in the East Asian cohort.
• Prioritized 36 credible genes, with enrichment for ultra-rare damaging variants in cases.
• Observed differences in genetic architecture by ascertainment source and bipolar disorder subtype (I/II).
• Implicated specific neuronal cell types, including GABAergic interneurons and medium spiny neurons.

Conclusions:

• This study significantly advances the understanding of bipolar disorder's genetic architecture.
• It highlights the convergence of common and rare variant signals in its etiology.
• Findings provide insights into the biological underpinnings and potential therapeutic targets for bipolar disorder.