A critical spotlight on the paradigms of FFPE-DNA sequencing.

Authors

Tim A Steiert, Genís Parra, Marta Gut, Norbert Arnold, Jean-Rémi Trotta, Raúl Tonda, Alice Moussy, Zuzana Gerber, Peter M Abuja, Kurt Zatloukal, Christoph Röcken, Trine Folseraas, Marit M Grimsrud, Arndt Vogel, Benjamin Goeppert, Stephanie Roessler, Sebastian Hinz, Clemens Schafmayer, Philip Rosenstiel, Jean-François Deleuze, Ivo G Gut, Andre Franke, Michael Forster

Year of publication

2023

Journal

NUCLEIC ACIDS RES

Volume

-

Issue

-

ISSN

0305-1048

Impact factor

14.9

Abstract

In the late 19th century, formalin fixation with paraffin-embedding (FFPE) of tissues was developed as a fixation and conservation method and is still used to this day in routine clinical and pathological practice. The implementation of state-of-the-art nucleic acid sequencing technologies has sparked much interest for using historical FFPE samples stored in biobanks as they hold promise in extracting new information from these valuable samples. However, formalin fixation chemically modifies DNA, which potentially leads to incorrect sequences or misinterpretations in downstream processing and data analysis. Many publications have concentrated on one type of DNA damage, but few have addressed the complete spectrum of FFPE-DNA damage. Here, we review mitigation strategies in (I) pre-analytical sample quality control, (II) DNA repair treatments, (III) analytical sample preparation and (IV) bioinformatic analysis of FFPE-DNA. We then provide recommendations that are tested and illustrated with DNA from 13-year-old liver specimens, one FFPE preserved and one fresh frozen, applying target-enriched sequencing. Thus, we show how DNA damage can be compensated, even when using low quantities (50 ng) of fragmented FFPE-DNA (DNA integrity number 2.0) that cannot be amplified well (Q129 bp/Q41 bp = 5%). Finally, we provide a checklist called ‘ERROR-FFPE-DNA’ that summarises recommendations for the minimal information in publications required for assessing fitness-for-purpose and inter-study comparison when using FFPE samples.