Amyloid Nomenclature 2020: Update and Recommendations by the International Society of Amyloidosis (ISA) Nomenclature Committee

The ISA Nomenclature Committee met electronically before and directly after the XVII ISA International Symposium on Amyloidosis, which, unfortunately, had to be virtual in September 2020 due to the ongoing COVID-19 pandemic instead of a planned meeting in Tarragona in March. In addition to confirmation of basic nomenclature, several additional concepts were discussed, which are used in scientific amyloid literature. Among such concepts are cytotoxic oligomers, protofibrils, primary and secondary nucleation, seeding and cross-seeding, amyloid signature proteins, and amyloid plaques.

Recommendations for their use are given. Definitions of amyloid and amyloidosis are confirmed. Possible novel human amyloid fibril proteins, appearing as 'classical' in vivo amyloid, were discussed. It was decided to include fibulin-like extracellular matrix protein 1 (amyloid protein: AEFEMP1), which appears as localised amyloid in portal veins.

The principles of the nomenclature have been given in earlier versions and for history. All amyloid fibril proteins are called protein A + the specific protein as a suffix, e.g. AL (L = immunoglobulin light chain) or ATTR (TTR = transthyretin). Further specification can be given after the protein name, e.g. ATTRwt or ATTRv (wt = wildtype and v = variant). If suitable, the specific mutation can replace v, e.g. ATTRV30M. Please observe that the Nomenclature Committee recommends the use of mature proteins in numbering of amino acid residues, i.e. without leader sequences.