This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary tract, Subject name: Pathology
Alpo&;s syndrome is due to defective- 
Select and explain. 
A. Collagen, B. Elastin, C. Fibrillin, D. Proteoglycan
A: Collagen
Answer: A: Collagen 
Explanation: Out of various hereditary nephritis, Alpo's syndrome is relatively more common and has been extensively studied. This is an X-linked dominant disorder having a mutation in a-5 chain of type IV collagen located on X-chromosome. Ref: Harsh Mohans textbook of pathology 6th edition page 678