NEFL encodes neurofilament light chain, a key intermediate filament protein essential for maintaining neuronal structure and function. As a structural constituent of the cytoskeleton, NEFL participates in neurofilament bundle assembly and axonal transport processes, working alongside other neurofilament proteins NEFM and NEFH to maintain neuronal caliber 1. The protein serves as a critical biomarker of neuroaxonal damage, with elevated plasma levels indicating neuronal injury across multiple neurological conditions 23. In multiple sclerosis, increased NEFL concentrations reflect acute inflammatory disease activity and axonal damage during relapses, making it valuable for monitoring treatment response 3. NEFL also functions as an early biomarker for dementia, with plasma levels increasing up to 15 years before clinical diagnosis and correlating with cognitive decline 45. Pathogenic variants in NEFL cause various forms of Charcot-Marie-Tooth disease, including demyelinating, axonal, and intermediate forms, demonstrating the protein's critical role in peripheral nerve function 1. Additionally, NEFL expression influences neuroblastoma susceptibility and progression, with higher expression levels associated with better survival outcomes 6. The protein's levels are elevated in amyotrophic lateral sclerosis and correlate with disease progression markers 7.