SMARCB1/INI1 Involvement in pediatric chordoma. A mutational and immunohistochemical analysis

Antonella Coli, Marco Gessi, Manila Antonelli, Alessandro Raso, Samantha Mascelli, Paolo Nozza, Marina P. Gardiman, Antonietta Arcella, Maura Massimino, Francesca R. Buttarelli, Felice Giangaspero

Risultato della ricerca: Contributo in rivistaArticolo in rivista

33 Citazioni (Scopus)

Abstract

Chordomas arise in the skull base and spine and usually occur in adults and are rare in the pediatric population. Cases of chordoma in pediatric age are often poorly differentiated, showing cytologic atypia, increased cellularity, and mitosis, and their aggressive behavior is associated with a high incidence of metastatic spread and a short patient survival. Recent studies have described loss of SMARCB1/INI1 protein in poorly differentiated chordomas associated not with point mutations but with SMARCB1/INI1 gene deletions instead. In this study, we considered immunohistochemistry and SMARCB1/INI1 mutational status to examine SMARCB1 status in a series of pediatric chordomas (7 classic and 1 poorly differentiated). We performed immunohistochemical tests for INI1, brachyury, S100, and cytokeratins and conducted a genetic analysis on the SMARCB1 coding sequence (NM_003073) using the Sanger method and multiplex ligation-dependent probe amplification to detect abnormal copy numbers of the gene locus. All 8 cases were positive for brachyury, whereas there was no nuclear SMARCB1/INI1 expression in 4 of the 8 cases, including the poorly differentiated chordoma. Genetic analysis identified a missense mutation in 2 cases and a nonsense mutation associated with loss of SMARCB1/INI1 protein and features of poorly differentiated tumor in 1. These mutations were novel variants occurring in heterozygosity, and they were judged to be pathogenic by 3 different bioinformatic tools. In 7 of 8 cases we performed multiplex ligation-dependent probe amplification, and 3 cases showed deletions at the SMARCB1 locus. Our results confirm the pathogenic involvement of SMARCB1/INI1 in childhood chordoma. We also describe 3 novel pathogenic mutations.
Lingua originaleEnglish
pagine (da-a)56-61
Numero di pagine6
RivistaTHE AMERICAN JOURNAL OF SURGICAL PATHOLOGY
DOI
Stato di pubblicazionePubblicato - 2017

Keywords

  • chordoma, atypical teratoid/rhabdoid tumor, multiplex ligation-dependent probe amplification (MLPA), INI1/SMARCB1 protein

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