Marfan syndrome is autosomal dominant connective tissue disorder from FBN1 (fibrillin-1) gene mutations on chromosome 15. Ghent nosology for diagnosis. Clinical features: skeletal (tall stature, arachnodactyly, pectus, scoliosis), ocular (lens subluxation upward, myopia, retinal detachment), cardiovascular (aortic root dilation, MVP, aortic dissection). Aortic root monitoring with annual echo. Beta-blockers or ARBs to reduce aortic wall stress. Prophylactic aortic root replacement when diameter reaches 5.0cm (or 4.5cm with risk factors). Avoid contact sports, isometric exercise.