Rethinking the connection between bipolar disorder and epilepsy from genetic perspectives

Epilepsy and bipolar disorder (BD) exhibit considerable biochemical and genetic overlap. Our study unveiled a significant genetic correlation ( r g = 0.154, P = 9.24 × 10 –6 ) between BD-I and epilepsy, indicating a meaningful causal effect of epilepsy on BD-I ( P = 0.0079, bxy = 0.1721, SE = 0.0648). Additionally, we identified 1.3k shared genetic variants and 6 significant loci, demonstrating substantial polygenic overlap. Notably, the rs9639379 variant within the SP4 gene exhibited strong associations with both BD-I and epilepsy, implicating SP4 in the etiology of both disorders.