eprintid: 10024837 rev_number: 36 eprint_status: archive userid: 608 dir: disk0/10/02/48/37 datestamp: 2017-10-17 11:17:40 lastmod: 2021-09-30 22:43:49 status_changed: 2017-10-17 11:17:40 type: article metadata_visibility: show creators_name: Canetti, D creators_name: Rendell, NB creators_name: Di Vagno, L creators_name: Gilbertson, JA creators_name: Rowczenio, D creators_name: Rezk, T creators_name: Gillmore, JD creators_name: Hawkins, PN creators_name: Verona, G creators_name: Mangione, PP creators_name: Giorgetti, S creators_name: Mauri, P creators_name: Motta, S creators_name: De Palma, A creators_name: Bellotti, V creators_name: Taylor, GW title: Misidentification of transthyretin and immunoglobulin variants by proteomics due to methyl lysine formation in formalin-fixed paraffin-embedded amyloid tissue ispublished: pub divisions: UCL divisions: B02 divisions: C10 divisions: D17 divisions: G90 divisions: G93 keywords: Amyloidosis, formalin, immunoglobulin, proteomics, transthyretin, variant note: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. abstract: Proteomics is becoming the de facto gold standard for identifying amyloid proteins and is now used routinely in a number of centres. The technique is compound class independent and offers the added ability to identify variant and modified proteins. We re-examined proteomics results from a number of formalin-fixed paraffin-embedded amyloid samples, which were positive for transthyretin (TTR) by immunohistochemistry and proteomics, using the UniProt human protein database modified to include TTR variants. The amyloidogenic variant, V122I TTR, was incorrectly identified in 26/27 wild-type and non-V122I variant samples due to its close mass spectral similarity with the methyl lysine-modified WT peptide [126KMe]105-127 (p.[146 KMe]125-147) generated during formalin fixation. Similarly, the methyl lysine peptide, [50KMe]43-59, from immunoglobulin lambda light chain constant region was also misidentified as arising from a rare myeloma-derived lambda variant V49I. These processing-derived modifications are not present in fresh cardiac tissue, non-fixed fat nor serum and do not materially affect the identification of amyloid proteins. They could result in the incorrect assignment of a variant, and this may have consequences for the immediate family who will require genetic counselling and potentially early clinical intervention. As proteomics becomes a routine clinical test for amyloidosis, it becomes important to be aware of potentially confounding issues such as formalin-mediated lysine methylation, and how these may influence diagnosis and possibly treatment. date: 2017 date_type: published official_url: https://doi.org/10.1080/13506129.2017.1385452 oa_status: green full_text_type: other language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 1434955 doi: 10.1080/13506129.2017.1385452 lyricists_name: Bellotti, Vittorio lyricists_name: Canetti, Diana lyricists_name: Gilbertson, Janet lyricists_name: Gillmore, Julian lyricists_name: Hawkins, Philip lyricists_name: Mangione, Palma lyricists_name: Rendell, Nigel lyricists_name: Rezk, Tamer lyricists_name: Rowczenio, Dorota lyricists_name: Taylor, Graham lyricists_name: Verona, Guglielmo lyricists_id: VBELL78 lyricists_id: DCANE19 lyricists_id: JAGIL44 lyricists_id: JGILL78 lyricists_id: PNHAW77 lyricists_id: PMANG84 lyricists_id: NREND34 lyricists_id: TMIRE17 lyricists_id: DROWC07 lyricists_id: GTAYL13 lyricists_id: GVERO54 actors_name: Taylor, Graham actors_id: GTAYL13 actors_role: owner full_text_status: public publication: Amyloid volume: 27 number: 4 pagerange: 229-237 event_location: England issn: 1744-2818 citation: Canetti, D; Rendell, NB; Di Vagno, L; Gilbertson, JA; Rowczenio, D; Rezk, T; Gillmore, JD; ... Taylor, GW; + view all <#> Canetti, D; Rendell, NB; Di Vagno, L; Gilbertson, JA; Rowczenio, D; Rezk, T; Gillmore, JD; Hawkins, PN; Verona, G; Mangione, PP; Giorgetti, S; Mauri, P; Motta, S; De Palma, A; Bellotti, V; Taylor, GW; - view fewer <#> (2017) Misidentification of transthyretin and immunoglobulin variants by proteomics due to methyl lysine formation in formalin-fixed paraffin-embedded amyloid tissue. Amyloid , 27 (4) pp. 229-237. 10.1080/13506129.2017.1385452 <https://doi.org/10.1080/13506129.2017.1385452>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10024837/1/N%3A%5CAAGWT%20WORKING%5CMANUSCRIPTS%5CMethyl%20lysine%20paper%20Mar%202017%5CMethyl%20lysine%20in%20formalin%20Amyloid%20Final%20UCL%20uploaded.pdf