An 11-year-old boy presents with complaints of blurred vision. Ophthalmologic evaluation reveals bilateral subluxated lens. Cardiac examination reveals a heart murmur. He has a tall stature with kyphosis and long legs and hands.

A peculiar sign is elicited in his fingers as shown in the photograph. What is the probable diagnosis? Source: AK Randhawa et al. Niger J Clin Pract 2012;15:364-8.