TTR and primary systemic amyloidosis: Whilst systemic amyloidosis has traditionally been associated with the presence of destabilized protein variants, such as lysozyme or transthyretin (TTR), or markedly increased plasma protein concentrations (SAA) (Merlini and Bellotti, 2003), epidemiological studies have shown that there is also an association of amyloid with aging (Blumenthal, 2004; Trigo et al., 2019; Tasaki et al., 2021) (Table 1).