TTR and early-onset autosomal dominant Alzheimer disease: More than 30 causative amyloidogenic proteins have been reported, and some of them, such as the amyloid β precursor protein (APP) in Alzheimer’s disease, prion protein in prion diseases, immunoglobulin light chain in AL amyloidosis, transthyretin (TTR) in ATTR amyloidosis, and serum amyloid A in AA amyloidosis, cause fatal outcomes [1,3,4,5,6,7,8].