This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amyloidosis, Subject name: Pathology
Which type of amyloidosis is caused by mutations in transthyretin gene? 
Select and explain. 
A. Familial Mediterranean fever, B. Familial amyloidosis polyneuropathy, C. Dialysis associated amyloidosis, D. Prion protein associated amyloidosis
B: Familial amyloidosis polyneuropathy
Answer: B: Familial amyloidosis polyneuropathy 
Explanation: Transthyretin (TTR) is a normal serum protein that binds and transpos thyroxine and retinol. Several distinct mutant forms of TTR (and its fragments) are deposited in a group of genetically determined disorders referred to as familial amyloid polyneuropathies. Normal TTR is also deposited (Due to overproduction) in the hea of aged individuals (senile systemic amyloidosis).