Stains & molecular markers

Topic Completed: 1 August 2014

Minor changes: 2 September 2020

Copyright: 2003-2020,, Inc.

PubMed Search: BAP1[TI] free full text[sb]

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Cite this page: Bradish J. BAP1. website. Accessed September 23rd, 2020.
Definition / general
  • BAP1: BRCA1 Associated Protein 1, on chromosome 3p21
  • Involved in cell cycle regulation, cellular differentiation, cell death, DNA damage response (Nat Rev Cancer 2013;13:153)
  • BAP1 is a ubiquitin carboxy terminal hydrolase (deubiquitylase)
Diagrams / tables

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BAP1 interactions

Clinical features
  • BAP1 has been associated with a cancer syndrome involving a predisposition to benign melanocytic nevi, mesothelioma, uveal melanoma and cutaneous melanoma (Nat Rev Cancer 2013;13:153)
  • Many BAP1 mutations have a concomitant BRAF mutation
  • One study found 85% of metastasizing uveal melanomas contained a BAP1 mutation (Science 2010;330:1410)
  • Lack of BAP1 expression has been associated with aggressive disease and worse survival (Pathology 2013;45:651)
  • Histone deacetylase inhibitors may be effective in uveal melanoma cell lines with a BAP1 mutation (Clin Cancer Res 2012;18:408)
Microscopic (histologic) description
  • Benign melanocytic nevi associated with BAP1 germline mutations are often spitzoid or epitheliod
    • These melanocytic tumors may have overlapping features with melanoma
    • Spitzoid tumors often lack epidermal hyperplasia, Kamino bodies, clefting
    • Many lesions are highly cellular, pleomorphic and can contain molecular aberrations occasionally identified in melanoma (Nat Genet 2011;43:1018)
Mechanisms of resistance
  • None evaluated
Molecular / cytogenetics description
  • Many different types of mutations (deletions, point mutations, etc.) can lead to inactivation of BAP1 function, which is problematic for detection using molecular techniques (Pathology 2013;45:651)
  • Development of a molecular assay is difficult and laborious, due to numerous types of inactivating mutations found in BAP1
  • Currently, an immunohistochemical stain is the choice for detection of BAP1 mutations with subsequent inactivation (Pathology 2013;45:651)
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