ELFN1 encodes a postsynaptic cell adhesion molecule that plays critical roles in synaptic organization and neuronal circuit regulation. The protein functions as a transmembrane leucine-rich repeat protein involved in signal transduction and synaptic communication 1. ELFN1 regulates membrane trafficking and postsynaptic localization through its intracellular domain, while the extracellular leucine-rich repeat domain mediates homodimerization, which is essential for proper synaptic function 2. Mechanistically, ELFN1 exists as an obligate homodimer and can form heterodimers with its homolog ELFN2 2. The protein modulates synaptic communication and is particularly involved in interneuron function, as evidenced by downregulated interneuron transcript networks in disease states 3. Clinically, biallelic ELFN1 mutations cause a distinct neurodevelopmental disorder characterized by developmental delay, intellectual disability, epileptic encephalopathy, movement disorders, and joint laxity 14. Functional studies in animal models demonstrate that ELFN1 loss results in motor activity abnormalities and seizures 4. Additionally, ELFN1 has been identified as a genetic risk factor for PTSD through genome-wide association studies, highlighting its broader role in psychiatric disorders 35.