title: Low-level constitutional mosaicism of a de novoBRCA1 gene mutation.
abstract: BACKGROUND
  Pathogenic BRCA1 mutations are usually inherited. Constitutional low-level BRCA1 mosaicism has never been reported.
  
  
  METHODS
  Next-generation sequencing (NGS) of cancer gene panel of germline and tumour DNA in a patient with early onset, triple-negative breast cancer.
  
  
  RESULTS
  Constitutional de novo mosaicism (5%) for a pathogenic (c.1953dupG; p.Lys652Glufs*21) BRCA1mutation was detected in leukocytes, buccal tissue and normal breast tissue DNA, with ∼50% mutation in tumorous breast tissue.
  
  
  CONCLUSIONS
  This is the first reported case of low-level, multiple tissue, constitutional mosaicism in BRCA1, and highlights the need to consider deep sequencing in affected individuals clinically suspected of having cancer predisposition whose tumours display a BRCA mutation.
authors: 1] The Susanne Levy Gertner Oncogenetics Unit, The Danek Gertner Institute of Human Genetics, Chaim Sheba Medical Center at Tel-Hashomer, Tel-Aviv 5262100, Israel [2] Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, 5262100, Israel.
authors: E
authors: E
authors: Friedman
authors: Department of Oncology, Kaplan Medical Center, Rehovot, Israel.
authors: N
authors: N
authors: Efrat
authors: Oncotest-Teva, Teva Pharmeceuticals Industries, Petach Tikva 49510, Israel.
authors: L
authors: L
authors: Soussan-Gutman
authors: Oncotest-Teva, Teva Pharmeceuticals Industries, Petach Tikva 49510, Israel.
authors: A
authors: A
authors: Dvir
authors: Oncotest-Teva, Teva Pharmeceuticals Industries, Petach Tikva 49510, Israel.
authors: Y
authors: Y
authors: Kaplan
authors: Invitae Corp., San Francisco, California 94107, USA.
authors: T
authors: T
authors: Ekstein
authors: Invitae Corp., San Francisco, California 94107, USA.
authors: K
authors: K
authors: Nykamp
authors: Invitae Corp., San Francisco, California 94107, USA.
authors: M
authors: M
authors: Powers
authors: Invitae Corp., San Francisco, California 94107, USA.
authors: M
authors: M
authors: Rabideau
authors: Invitae Corp., San Francisco, California 94107, USA.
authors: J
authors: J
authors: Sorenson
authors: Invitae Corp., San Francisco, California 94107, USA.
authors: S
authors: S
authors: Topper
mesh_terms: D000328:Adult; D019313:BRCA1 Protein / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics*; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D009030:Mosaicism; D020125:Mutation, Missense; D020641:Polymorphism, Single Nucleotide
chemical_list: D019313:BRCA1 Protein; C492913:BRCA1 protein, human
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