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Ward A, Farengo-Clark D, McKenna DB, Safonov A, Good M, Le A, Kessler L, Shah PD, Bradbury AR, Domchek SM, Nathanson KL, Powers J, Maxwell KN. Clinical management of TP53 mosaic variants found on germline genetic testing. Cancer Genet 2024; 284-285:43-47. [PMID: 38677009 PMCID: PMC11168919 DOI: 10.1016/j.cancergen.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 03/23/2024] [Accepted: 04/22/2024] [Indexed: 04/29/2024]
Abstract
BACKGROUND Germline heterozygous TP53 pathogenic variants (PVs) cause Li Fraumeni Syndrome (LFS, OMIM#151623). TP53 PVs at lower-than-expected variant allele frequencies (VAF) may reflect postzygotic mosaicism (PZM) or clonal hematopoiesis (CH); however, no guidelines exist for workup and clinical management. PATIENTS AND METHODS Retrospective analysis of probands who presented to an academic cancer genetics program with a TP53 PV result on germline genetic testing. RESULTS Twenty-one of 125 unrelated probands (17 %) were found to harbor a TP53 PV with VAF<30 % or a designation of "mosaic". A diagnosis of PZM was made in nine (43 %) due to a clinical phenotype consistent with LFS with (n = 8) or without (n = 1) positive ancillary tissue testing. Twelve patients (57 %) were diagnosed with presumed CH (pCH) due to a diagnosis of a myeloproliferative neoplasm, negative ancillary tissue testing, clinical phenotype not meeting LFS criteria, no cancer, and/or no first cancer age<50. Of the 19 patients with biological offspring, nine had either partial or complete offspring testing, all negative. CONCLUSIONS Determining the etiology of low VAF TP53 PVs requires ancillary tissue testing and incorporation of clinical phenotype. Discerning PZM versus CH is important to provide optimal care and follow-up.
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Affiliation(s)
- Abigail Ward
- Master of Science in Genetic Counseling Program, Perelman School of Medicine, University of Pennsylvania, USA
| | - Dana Farengo-Clark
- Division of Hematology/Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, USA
| | - Danielle B McKenna
- Division of Hematology/Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, USA
| | - Anton Safonov
- Division of Translational Medicine and Human Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Madeline Good
- Division of Hematology/Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, USA
| | - Anh Le
- Division of Hematology/Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, USA
| | - Lisa Kessler
- Master of Science in Genetic Counseling Program, Perelman School of Medicine, University of Pennsylvania, USA
| | - Payal D Shah
- Division of Hematology/Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, USA
| | - Angela R Bradbury
- Division of Hematology/Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, USA
| | - Susan M Domchek
- Division of Hematology/Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, USA; Abramson Cancer Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Katherine L Nathanson
- Division of Translational Medicine and Human Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Abramson Cancer Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Jacquelyn Powers
- Division of Hematology/Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, USA
| | - Kara N Maxwell
- Division of Hematology/Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, USA; Abramson Cancer Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Corporal Michael Crescenz Veterans Affairs Medical Center, Philadelphia, PA, USA.
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Schwartz AN, Hyman SR, Stokes SM, Castillo D, Tung NM, Weitzel JN, Rana HQ, Garber JE. Evaluation of TP53 Variants Detected on Peripheral Blood or Saliva Testing: Discerning Germline From Somatic TP53 Variants. JCO Precis Oncol 2021; 5:1677-1686. [PMID: 34994652 DOI: 10.1200/po.21.00278] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 09/15/2021] [Accepted: 09/24/2021] [Indexed: 01/04/2023] Open
Abstract
PURPOSE Multigene panel testing (MGPT) identifies TP53 pathogenic or likely pathogenic (P/LP) variants in patients with diverse phenotypes, of which only one is classic Li-Fraumeni syndrome. Low variant allelic fraction (VAF) in TP53 found on germline testing may suggest aberrant clonal expansion or constitutional mosaicism. We evaluated TP53-positive probands seen in a cancer genetics program to determine germline versus somatic status. METHODS We reviewed TP53-positive probands from 2012 to 2019 identified by MGPT on blood or saliva (N = 84). Available VAFs were collected. Probands with a familial variant, who met Li-Fraumeni syndrome testing criteria or who carried a founder variant, were considered germline. For those with uncertain germline status, TP53 variants were further examined using ancillary data of family members and somatic tissue. RESULTS Of the 84 probands, 54.7% had germline variants with 33.3% meeting criteria for germline status and 21.4% confirmed through ancillary testing. Aberrant clonal expansion comprised 13.1% with clonal hematopoiesis of indeterminate potential and 2.4% with a hematologic malignancy. Constitutional mosaicism was confirmed in 8.3% probands. Definitive status could not be determined in 3.6% despite ancillary assessment, and 17.9% did not have ancillary testing. CONCLUSION A TP53 P/LP variant found on peripheral blood or saliva MGPT does not always originate in the germline. In a clinical cancer genetics cohort, approximately half of the patients had TP53 P/LP germline variants; these patients plus those with constitutional mosaicism require intensified surveillance. A framework of multiple strategies enables discernment of germline from constitutional mosaic and acquired variants, which is essential for appropriate management.
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Affiliation(s)
- Alison N Schwartz
- Division of Cancer Genetics and Prevention, Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
| | - Sophie R Hyman
- Division of Cancer Genetics and Prevention, Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
| | - Samantha M Stokes
- Division of Cancer Genetics and Prevention, Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
| | - Danielle Castillo
- Division of Clinical Cancer Genomics, Beckman Research Institute, City of Hope, Duarte, CA
| | - Nadine M Tung
- Harvard Medical School, Boston, MA
- Division of Hematology and Oncology, Beth Israel Deaconess Medical Center, Boston, MA
| | | | - Huma Q Rana
- Division of Cancer Genetics and Prevention, Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
- Harvard Medical School, Boston, MA
| | - Judy E Garber
- Division of Cancer Genetics and Prevention, Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
- Harvard Medical School, Boston, MA
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The Emerging Role of Hematopathologists and Molecular Pathologists in Detection, Monitoring, and Management of Myeloid Neoplasms with Germline Predisposition. Curr Hematol Malig Rep 2021; 16:336-344. [PMID: 34028637 DOI: 10.1007/s11899-021-00636-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2021] [Indexed: 12/12/2022]
Abstract
PURPOSE OF REVIEW Awareness, widespread availability, and routine use of sequencing techniques in work-up of myelodysplastic syndromes and acute myeloid leukemia have facilitated increased recognition of these entities arising in a background of germline predisposition disorders (GPD). RECENT FINDINGS The latest revisions to the WHO classification of myeloid neoplasms incorporate "myeloid neoplasms with germline predisposition" as a separate entity due to the therapeutic implications of this diagnosis. It has become apparent that some of these entities have unique recognizable morphologic findings that can be challenging to interpret at time. Hence, much needs to be studied, posing a new layer of complexity to hematopathologists and oncologists. A thorough understanding of cytogenetic and molecular findings during disease evolution is essential. Consequently, hematopathologists and molecular pathologists play an increasing role in recognition of bone marrow morphologic features that help in recognition of underlying GPD, monitoring, and prompt identification of progression.
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