Inherited breast cancer Flashcards
% of breast cancers that are inherited
5-10%
BRCA1 location
17q
BRCA2 location
13q
Other cancers that inherited breast cancer is linked with
Ovarian, prostate and pancreatic
Inherited breast cancer tends to present before what age
50 years
Inheritance pattern of inherited breast cancer
Autosomal dominant
Bilateral or unilateral breast cancer - which is more likely to be inherited?
Bilateral
BRCA - large or small genes?
Large
BRCA proteins are involved in
Repair of double strand breaks
Mutation types in BRCA1/2
Small indels and substitutions in both. BRCA1 - also have large deletions and duplications. Tend to result in truncated protein
Increased risk of male breast cancer if you have a mutation in
BRCA2
Population risk of breast cancer
12%
Population risk of ovarian cancer
1.3%
BRCA1 mutation increases breast cancer risk to
72%
BRCA2 mutation increases breast cancer risk to
69%
BRCA1 mutation increases ovarian cancer risk to
44%
BRCA2 mutation increases ovarian cancer risk to
17%
Does everyone with a BRCA1 or 2 mutation get breast/ovarian cancer?
No - incomplete penetrance
Where do inherited breast cancer referrals come from?
Tend to be clinical Genetics, will have had counselling
What clinical information will be on referrals for inherited breast cancer?
Family history, mutation may be known or unknown
Testing strategy for inherited breast cancer if have a family history and the mutation is known?
Predictive testing - Sanger/MLPA depending on the mutation
Testing strategy for inherited breast cancer if have a family history but the mutation is unknown?
NGS screen (MLPA if nothing found)
Patients with Li Fraumeni syndrome have mutations in which gene?
TP53
What type of tumours are most common in individuals with Li Fraumeni syndrome?
Breast, sarcomas, osteosarcoma (bone cancer)
