FBN1 encodes fibrillin-1, a cysteine-rich glycoprotein that is a primary constituent of extracellular microfibrils 1. Fibrillin-1 monomers polymerize into parallel head-to-tail bundles that are rigidified by calcium binding, providing biomechanical support and serving as scaffolding for elastic fiber formation 1. The protein contains multiple calcium-binding epidermal growth factor-like modules and transforming growth factor beta-binding motifs 2. FBN1 mutations cause Marfan syndrome, a pleiotropic autosomal dominant connective tissue disorder affecting the skeletal, ocular, and cardiovascular systems 3. Cardinal manifestations include proximal aortic aneurysm, ocular lens dislocation, and long-bone overgrowth 3. Disease pathogenesis involves altered transforming growth factor beta regulation 3. FBN1 mutations also underlie related fibrillinopathies associated with increased aortic dilatation and dissection risk 4. Clinical diagnosis requires evaluation of multiple organ systems; detection rates for FBN1 mutations are highest (72.5%) in classical Marfan syndrome presentations 4. Recent sequencing studies identified 181 mutations in a Chinese cohort with ocular manifestations, with 74.8% attributed to FBN1 5. Identification of mutations enables early diagnosis, genetic counseling, and preventive management of carriers 6.