TTR and familial amyloid neuropathy: Although 30 amyloidogenic proteins are known, in 95% of cases CA is caused by the deposition of misfolded monoclonal immunoglobulin light chain (AL) derived from an abnormal clone of plasma cell proliferation (AL amyloidosis [37]) or misfolded transthyretin (TTR), a protein synthesized by the liver and involved in the transport of the hormone thyroxine and retinol-binding protein (TTR amyloidosis [38]).