Background Knowing the genetic status of patients affected by paragangliomas and pheochromocytomas (PPGL) is important for the guidance of their management and their relatives. Our objective was to improve the diagnostic performances of PPGL genetic testing by next-generation sequencing (NGS).
Methods We developed a custom multigene panel, which includes 17 PPGL genes and is compatible with both germline and tumour DNA screening. The NGS assay was first validated in a retrospective cohort of 201 frozen tumour DNAs and then applied prospectively to 623 DNAs extracted from leucocytes, frozen or paraffin-embedded PPGL tumours.
Results In the retrospective cohort, the sensitivity of the NGS assay was evaluated at 100% for point and indels mutations and 86% for large rearrangements. The mutation rate was re-evaluated from 65% (132/202) to 78% (156/201) after NGS analysis. In the prospective cohort, NGS detected not only germline and somatic mutations but also co-occurring variants and mosaicism. A mutation was identified in 74% of patients for whom both germline and tumour DNA were available.
Conclusion The analysis of 824 DNAs from patients with PPGL demonstrated that NGS assay significantly improves the performances of PPGL genetic testing compared with conventional methods, increasing the rate of identified mutations and identifying rare genetic mechanisms.
- next generation sequencing
- somatic mutations
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Contributors LBA, PP, LJCV and AB: performed the experiments. LBA, PP, JF, APGR and NB: designed the experiments. LBA, PP, LJCV, AB, JF, APGR and NB: collected the data and contributed to the interpretation of results. LA, JB, DD, IG, EB, CLL, CC, GC, CB, LF, CCB and APGR: provide and cared for studied patients. LBA, JF, APGR and NB: wrote the manuscript. APGR and NB: supervised the study. All authors approved the final version of the manuscript.
Funding This work has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 633983 and by the Institut National du Cancer and the Direction Générale de l’Offre de Soins (PRT-K 2014, COMETE-TACTIC, INCa-DGOS_8663). N. Burnichon received financial support from the Cancer Research for Personalized Medicine - CARPEM project (Site de Recherche Intégré sur le Cancer – SIRIC). The team is supported by the Ligue Nationale contre le Cancer (Equipe Labellisée). This work is part of the ‘Cartes d’Identité des Tumeurs (CIT) program’ funded and developed by the ‘Ligue Nationale contre le Cancer’ (http://cit.ligue-cancer.net).
Competing interests None declared.
Ethics approval Institutional Review Board (IRB 00003835, Comité de Protection des Personnes Ile de France IV).
Provenance and peer review Not commissioned; externally peer reviewed.
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