Summary: A new genetic study reveals a measurable connection between bipolar disorder type I (BD-I) and epilepsy, identifying shared genetic variants, several overlapping genomic loci, and a potential causal relationship. The research highlights the SP4 gene as a promising molecular link and suggests that therapies such as lithium may act on shared biological pathways. These findings point toward more personalized treatment approaches for patients affected by BD-I and epilepsy and have broader implications for other neuropsychiatric conditions.
Researchers from the Chinese Academy of Sciences report evidence that bipolar disorder type I and epilepsy share genetic architecture and may influence one another at a biological level. Published in Genomic Psychiatry on September 30, 2024, the study analyzed large-scale genome-wide association study (GWAS) datasets from European-ancestry populations to map overlapping genetic signals between the two disorders.
Using GWAS summary statistics that included more than 26,000 epilepsy cases and 25,000 BD-I cases with their controls, the team led by Dr. Ming Li at the Kunming Institute of Zoology applied advanced statistical techniques to quantify genetic correlation, identify shared variants, locate overlapping loci, and test causal relationships.
Key findings include a statistically significant positive genetic correlation (rg = 0.154) between BD-I and epilepsy, the identification of roughly 1,300 genetic variants that influence both conditions, and the discovery of six independent genomic loci associated with both disorders. In addition, the analyses indicated a notable causal effect of epilepsy on BD-I (P = 0.0079).
Among shared molecular signals, the SP4 gene emerged as particularly noteworthy. SP4 encodes a transcription factor whose activity is modulated by neuronal signaling. Prior work links SP4 activity to mood regulation and to the cellular actions of lithium, a first-line mood stabilizer used in bipolar disorder. The new results suggest SP4 could represent a convergent target for interventions that address both mood instability and seizure susceptibility.
The genetic overlap helps explain why some pharmacological agents, such as mood stabilizers, show efficacy across both clinical conditions. It also supports the idea that overlapping pathophysiology underlies at least a subset of patients with BD-I and epilepsy. By mapping shared variants and loci, the study provides testable hypotheses about the molecular pathways that drive comorbidity and offers candidate genes for functional follow-up studies.
Clinical and research implications are several-fold. First, the findings support greater collaboration between neurology and psychiatry to integrate genetic data into diagnosis and treatment planning. Second, they motivate precision medicine strategies in which genetic profiles inform the choice or development of treatments tailored to the underlying biology. Third, these results suggest that other neuropsychiatric disorders—such as schizophrenia or autism spectrum disorder—may also share genetic risk with epilepsy and mood disorders, warranting comparative genomic investigations.
The authors acknowledge key limitations. The analyses were restricted to GWAS data from European-ancestry cohorts and used publicly available summary data without sex-stratified results, which limits conclusions about generalizability and potential sex-specific genetic effects. Future work should expand to diverse populations and include sex-specific and longitudinal data to better capture how shared genetic risk manifests across groups and across the lifespan.
In summary, this study strengthens the evidence for a genetic connection between BD-I and epilepsy, identifies concrete genomic targets—including SP4—for further study, and highlights the potential to translate genetic insights into targeted, personalized therapeutic approaches. Continued research integrating genomics, neurobiology, and clinical data will be essential to move from discovery to treatments that improve outcomes for patients with these overlapping brain disorders.
About this genetics, bipolar disorder, and epilepsy research news
Author: Ma-Li Wong
Source: Genomic Press
Contact: Ma-Li Wong – Genomic Press
Image: Image credited to Neuroscience News
Original Research: Open access. “Rethinking the connection between bipolar disorder and epilepsy from genetic perspectives” by Ming Li et al., Genomic Psychiatry. Published September 30, 2024.