INSYN2B (inhibitory synaptic factor family member 2B) is a gene located on chromosome 5 with emerging roles in neuropsychiatric and neurodegenerative diseases. Primary function: INSYN2B is involved in neurotransmission and neurodevelopment processes 12. Mechanism: Fine-mapping studies have identified INSYN2B as a likely causal gene at bipolar disorder risk loci, with convergent evidence from brain cell-type epigenomic annotations, brain quantitative trait loci, and rare variant sequencing supporting its involvement in disease pathogenesis 12. Disease relevance: INSYN2B variants have been implicated in bipolar disorder through genome-wide association studies 12. Additionally, a 3'UTR variant in INSYN2B showed linkage to Alzheimer's disease in African American families, with segregation analysis indicating functional evidence for disease association 3. Promoter and enhancer region variants in INSYN2B were identified in multiple African American families with Alzheimer's disease 3. Clinical significance: INSYN2B represents a promising candidate for functional experiments to understand biological mechanisms underlying bipolar disorder and potentially Alzheimer's disease, particularly in African ancestry populations 123. However, specific molecular mechanisms and functional consequences remain to be elucidated through further investigation.