Familial cancer syndromes Flashcards
What is multi-stage carcinogenesis?
A series of genetic changes occuring within cells leading to increasingly abnormal behaviour and histology.
What are gatekeeper genes?
Monitor and control cell division and death - prevent the accumulation of mutations ep p53.
Mutation gives you more than 90% risk of cancer.
What are caretaker genes?
Improve genomic stability eg repair.
Mutation gives you 70% risk of cancer.
What are landscaper genes?
Control the surrounding stromal environment (stromal cells).
Mutation gives 10-20% risk of cancer.
What are oncogenes?
Control growth and development.
Experience gain of function mutation.
What are tumour supressor genes?
Gatekeeper/caretaker genes.
Experience loss of function mutation.
Must loose both alleles.
What is Knudson’s two hit hypothesis?
Must knock out both tumour supressor alleles?
Considering that cancer is recessive on a cellular level, why are most cancer syndromes autosomal dominant when inherited?
An individual need only inherit one knocked out tumour supressor allele. As soon as the other is spontaneously knocked out they will have cancer.
Which cancer syndromes are autosomal recessive?
Fanconi’s anaemia
Ataxia telangiectasia,
MYH associated polyposis
What are the features of familial cancer syndromes?
Onset a younger age
Multiple primaries
Other family members affected
Same type/genetically related cancers.
What are the features of sporadic cancer?
Onset at older age
One primary
Unaffected family members
Cancers that are rarely genetic (cervix, lung).
Which tumour suppressor gene is responsible for familial adenomatous polyposis?
APC
What kind of genes are involved in hereditary non-polyposis colorectal cancer?
Mismatch repair genes
What is the function of the BRCA genes?
DNA repair.
How many cases of breast cancer have BRCA?
Around 10% under 40.
