<prompt> Pathology in Marfan syndrome ?Fibrillin IFibrillin IICollegenElastin  <response>: Ans. is a i.e., Fibrillin I o Marfan syndrome is an autosomal dominant disorder due to mutation in fibrillin-1 gene on chromosomal 15.Fibrillin-1 is a part of elastic fibres, thus defect in fibrillin-1 affects following systems:-1 Skeletal abnormalities: Tall with thin built; arachnodactyly long and slender fingers and hand, spider like; decrease in upper segment: Lower segment body ratio i.e. lower limbs are proportionately more lengthened; scoliosis and kyphosis; pectus excavatum and pectus craniatum; Hypermobility laxity of joint with hyperextensibly; high arched palate and dolicocephalic skull.2 CVS abnormalities : Mitral valve prolapse causing mitral regurgitation; aortic aneurysm begning at base of aorta and involving ascending aorta; cystic medial necrosis causing dissection of aorta most common cause of death.3 Ocular abnormalities: Ectopia lends with bilateral superolateral lens dislocation, elongated eyeball.4 Others: Spontaneous pneumothorax ; inguinal and incisional hernias. 