Articlepre- and post-zygotic TP53 de novo mutations in SHH-medulloblastoma

Jacopo Azzollini, Elisabetta Schiavello, Francesca Romana Buttarelli, Carlo Alfredo Clerici, Laura Tizzoni, Giovanna De Vecchi, Fabio Capra, Federica Pisati, Veronica Biassoni, Letterio Runza, Giorgio Carrabba, Felice Giangaspero, Maura Massimino, Valeria Pensotti, Siranoush Manoukian

Research output: Contribution to journalArticlepeer-review


Li-Fraumeni syndrome (LFS) is an autosomal dominant disorder caused by mutations in the TP53 gene, predisposing to a wide spectrum of early-onset cancers, including brain tumors. In medulloblastoma patients, the role of TP53 has been extensively investigated, though the prevalence of de novo mutations has not been addressed. We characterized TP53 mutations in a monocentric cohort of consecutive Sonic Hedgehog (SHH)-activated medulloblastoma patients. Germline testing was offered based on tumor p53 immunostaining positivity. Among 24 patients, three (12.5%) showed tumor p53 overexpression, of whom two consented to undergo germline testing and resulted as carriers of TP53 mutations. In the first case, family history was uneventful and the mutation was not found in either of the parents. The second patient, with a family history suggestive of LFS, unexpectedly resulted as a carrier of the mosaic mutation c.742=/C>T p.(Arg248=/Trp). The allele frequency was 26% in normal tissues and 42–77% in tumor specimens. Loss of heterozygosity (LOH) in the tumor was also confirmed. Notably, the mosaic case has been in complete remission for more than one year, while the first patient, as most TP53-mutated medulloblastoma cases from other cohorts, showed a severe and rapidly progressive disease. Our study reported the first TP53 mosaic mutation in medulloblastoma patients and confirmed the importance of germline testing in p53 overexpressed SHH-medulloblastoma, regardless of family history.

Original languageEnglish
Article number2503
Number of pages16
Issue number9
Publication statusPublished - Sep 2020


  • De novo mutation
  • Li-Fraumeni syndrome
  • Medulloblastoma
  • Somatic mosaicism
  • TP53

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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