Tuesday, January 23, 2018
Repeated USMLE Questions Step 1- 219
A 23 year old man with a history of Marfan syndrome presents to the ER complaining of sharp pain on the upper back. He is admitted to intensive care unit (ICU) for the risk of aortic dissection.
Which of the following proteins are responsible for the probable development of abdominal aortic aneurysm (AAA) in this patient?
A-Myosin and actin
B-Fibrin and actin
C-Fibrillin and elastin
D-Myosin and fibrin
Marfan syndrome is a connective tissue disorder caused by FBNI gene mutation on chromosome 15 which results in defective fibrillin. It affects bones, heart, large vessels and eyes. Patients are tall with long extremities, hypermobile joints and long tapering fingers and toes. Aortic aneurysm develops due to cystic medial necrosis of the aorta.
Myosin and actin are not directly affected in Marfan syndrome. It affects fibrillin which forms a sheath around elastin.
The correct answer is C