BFSP2 encodes CP49, a lens-specific intermediate filament protein that is essential for proper eye lens structure and optical properties 1. BFSP2 functions as part of the beaded filament cytoskeleton, the major structural element in lens fiber cells, working in complex with BFSP1 (filensin) to form unique intermediate filaments 2. Unlike canonical intermediate filament proteins, BFSP2 is completely tailless and cannot form filaments independently in vitro, requiring co-assembly with BFSP1 to generate functional beaded filaments 3. These beaded filaments are fundamental for organizing and maintaining lens fiber cell architecture and determining the optical properties essential for lens transparency 3. BFSP2 mutations cause autosomal dominant and recessive forms of congenital cataract, with the ΔE233 deletion being the first reported cytoskeletal protein mutation causing inherited cataract 4. The protein shows evolutionary variation, with fish orthologs possessing C-terminal tail domains that regulate filament assembly and diameter, while mammalian BFSP2 is tailless 5. Clinical studies have identified multiple pathogenic BFSP2 variants in pediatric cataract patients, emphasizing its critical role in lens development and maintenance 6.