A young, tall, thin male with arachnodactyly has ectopia lentis in both eyes. The most likely diagnosis is:

Marfan syndrome Disorder of connective tissues, Changes in the skeleton, eyes, and cardiovascular system. Inherited defect in an extracellular glycoprotein called fibrillin-1. Skeleton features Unusually tall with long extremities and long,tapering fingers (refer to the image below) and toes. The joint ligaments in the hands and feet are lax. Ocular features Ectopia lentis (refer to the image below): Bilateral subluxation or dislocation (outward) of the lens Cardiovascular lesions Mitral valve prolapse Aoic dissection. (Fig: long fingers, ectopia lentis and chest in Marfan syndrome)