11. Cancer Genetics Flashcards
cancer
a disorder of cell growth
caused by alterations in genes which control cell growth
germline mutations
present in sperm or egg
are heritable
cause cancer family syndromes
somatic mutations
occur in non germline tissues
are nonheritable
who is at risk to hereditary cancer
hereditary cancers account for only a small proportion of all cancer
the cancer family history is the key to:
accurate risk assessment
effective genetic counselling
appropriate medical follow-up
when to suspect hereditary cancer syndrome
- cancer in 2 or more close relatives
- early age diagnosis
- multiple primary tumours
- bilateral or multiple rare cancers
incomplete penetrance
when you have the gene alteration but never show it (symptoms)
what are the two ways of classifying hereditary cancer
by tumour type
by type of gene mutated
what are the two main groups of tumour types
rare hereditary cancer syndromes
subset of common cancers which is hereditary, eg. colon cancer, breast cancer, ovarian cancer
what are the three type of genes that can be mutated
tumour suppressor genes
oncogenes
DNA damage-response genes
explain tumour suppressor genes
they slow down cell growth (like breaks)
cancer arises when both breaks fail
Retinoblastoma
tumour that develops in the pigment cells in the back of a childs eye
- occurs in heritable and nonheritable forms
- autosomal dominant transmission
non heritable retinoblastoma
- unilateral tumour
- no family history
- avg age of diagnosis is 2+
heritable retinoblastoma
- bilateral tumour
- 20% of cases have family history
- avg age of diagnosis is less than 1
familial adenomatous polyposis
- autosomal disorder, fully penetrant
- development of multiple initally benign colonic polyps and if untreated will progress into colon cancer