This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inborn Errors of Metabolism, Subject name: Pediatrics
Ectopia lentis in a child is seen in which of the following diseases? 
Select and explain. 
A. Sarcoidosis, B. Homocystinuria, C. Alkaptonuria, D. Urea cycle defects
B: Homocystinuria
Answer: B: Homocystinuria 
Explanation: b. Homocystinuria(Ref: Nelson 20/e p 326)Ectopia lentis is one of the features of Homocystinuria, where the direction of lens subluxation is infero-medial, unlike supero-lateral subluxation in Marfan syndrome.