A tall, lanky 13-year-old boy presents to the ophthalmologist with a sudden change in vision

Medicoman · October 25, 2018, 9:03am

A tall, lanky 13-year-old boy presents to the ophthalmologist with a sudden change in vision. Examination shows lens subluxation. The patient has always been tall and thin for his age, and a family history reveals that his uncle died from a ruptured aortic aneurysm. On physical examination, the patient is found to have long and slender fingers, ligament laxity, an abnormal ratio of arm length to height, and a diastolic murmur over the aortic area. Which of the following is most likely deficient in this patient?.