This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Biochemistry
Marfan syndrome is due to mutation of: 
Select and explain. 
A. Collagen, B. Elastin, C. Fibrillin, D. Fibronectin
C: Fibrillin
Answer: C: Fibrillin 
Explanation: Marfan syndrome is caused by mutations in the FBN1 gene on chromosome 15, which encodes Fibrillin-1. Fibrillin normally binds to TGF-b (Transforming Growth Factor) Mutated fibrillin can't bind to TGF-b. Elevated levels of TGF-b contribute to the features of Ectopia lentis, arachnodactyly, and aoic dilatation.