This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Familial amyloidotic polyneuropathy is due to amyloidosis of nerves caused by deposition of ? 
Select and explain. 
A. Amyloid associated protein, B. Mutant Calcitonin, C. Mutant Transthyretin, D. Normal transthyretin
C: Mutant Transthyretin
Answer: C: Mutant Transthyretin 
Explanation: Ans. is 'c' i.e., Mutant transthyretinTransthyretin (ATTR) amyloid Transthyretin (TTR) is normal serum protein that binds and transpo thyroxine and retinol.o TTR can cause following types of amyloidosis : ?1. Mutant TTR : - Mutation in TTR can cause syndrome of familial amyloidotic polyneuropathy or familial amylodotic cardiotnyopathy.2. Wild (non-mutant) TTR : - There is no mutation of TTR and wild type TTR forms fibrils which results in senile systemic amyloidosis (senile cardiac amyloidosis).