This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cytogenetic Disorders, Subject name: Pathology
[{'content': 'A 22-year-old man has features of arm span greater than height, subluxed lenses, flattened and dilation of the aortic most likely diagnosis is? \nSelect and explain. \nA. Ehlers-Danlos syndrome, B. Marfan syndrome, C. Werners syndrome, D. Laurence-Moon-Biedl syndrome', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. (b) Marfan syndromeRef: Robbin's pathology 9th ed. /144* The presentation in the question is of a patient with Marfan syndrome.* Marfan syndrome is caused by a mutation in a single allele of the fibrillin gene (FBN1).* The gene product is a major component of elastin- associated microfibrils. Long, thin extremities; ectopial entis; and aortic aneurysms are the classical triad.* Mutations in the FBN2 gene can also cause Marfan syndrome, but without aneurysms.", 'role': 'assistant'}]