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Symbol BRCA1 contributors: mct/shn - updated : 03-06-2019
HGNC name breast cancer 1, early onset
HGNC id 1100
corresponding disease(s) BRCA1 , FANCS
related resource Breastcancer
Other morbid association(s)
TypeGene ModificationChromosome rearrangementProtein expressionProtein Function
tumoral     --low  
or loss of function in breast, ovarian carcinomas (sporadic or not)
tumoral germinal mutation      
increased risk of Prostate carcinoma in men
constitutional     --over  
in proliferative cells
tumoral germinal mutation     loss of function
in patients with primary ovarian, fallopian tube, or peritoneal cancers
tumoral       loss of function
BRCA1 loss activates CTSL1-mediated degradation of TP53BP1
tumoral       loss of function
loss of BRCA1 following HSP90AA1 inhibition is a key upstream event leading to defective DSB repair, failure of G2/M checkpoint activation, and potentiation to DNA damaging agents
Susceptibility to breast cancer
Variant & Polymorphism
Candidate gene
Therapy target
clinically relevant target for enhancing sensitivity in refractory and/or resistant malignancies
MIR155 is a potential therapeutic target for BRCA1-deficient tumors
Treatment of Brca1/p53-deficient mice with the progesterone antagonist mifepristone (RU 486) prevented mammary tumorigenesis
is a clinically relevant target for enhancing sensitivity in refractory and/or resistant malignancies
  • mice homozygous for the mutant BRCA1 allele died in utero between 10 and 13 days of gestation due to abnormalities in the neural tube, spina bifida and anencephaly
  • Brca1+/- mice are normal and fertile and lack tumors by age eleven months, while Brca1-/- mice die before day 7.5 of embryogenesis due to a failure of the proliferative burst
  • Brca1-deficient mouse embryonic stem cells have impaired repair of chromosomal DNA double-strand breaks by homologous recombination
  • impact of the Brca1 or Brca2 null mutation is less severe in a p53 null background
  • mice deficient in the Brca1 exon 11 isoform (Brca1Delta11/Delta11) died late in gestation because of widespread apoptosis
  • most female Brca1Delta11/Delta11 Trp53+/- mice develop mammary tumors with loss of the remaining Trp53 allele within 6-12 months
  • Brca1(Delta11/Delta11)Gadd45a(-/-) embryos at embryonic days 9.5-10.5 were exencephalic and exhibited a high incidence of apoptosis accompanied by altered levels of BAX, BCL-2, and p53