TTR and primary systemic amyloidosis: More than 30 amyloid proteins have been identified; some result in localized tissue deposits, such as Aβ in Alzheimer's disease and α-synuclein (αSyn) in Parkinson’s disease that deposit in the brain, while others result in systemic amyloidosis and are widely deposited in various tissues and organs, such as ALλ and ALκ in immunoglobulin light chain amyloidosis and transthyretin in ATTR amyloidosis (Benson et al., 2018).