familial cancer Flashcards
1
Q
indicators of familial cancer
A
- involvement of close relatives - at least one first degree
- presence of cancer over successive generations
- young age at onset of cancer
- multiple types of cancer (in same individual or family)
2
Q
molecular basis of familial cancer
A
germline mutation of genes belonging to the same gene families involved in acquired cancers
3
Q
hereditary non polyposis colorectal cancer (HNPCC)
A
- autosomal dominant inheritance
- multisystem disorder (cause other cancers)
- caused by inherited abnormality of a DNA mismatch repair gene
4
Q
Genetics of HNPCC
A
heterozygous for germline mutation in DNA mismatch repair gene
- inherited mutation of 1 allele
- increases progression from adenoma to carcinoma
5
Q
implications of defective mismatch repair
A
- inactivation of both alleles increases the mutation rate
- alters a number of cell regulatory genes (increased risk of cancer)
- microsatellite instability seen in the cancer
6
Q
microsatellite instability
A
biomarker for a DNA mismatch repair gene defect
7
Q
BRAC1 and BRAC2 genes
A
- germline mutation in breast cancer
- proteins involved in DNA repair
- not 100% risk - not fully penetrance
- other modifying factors e.g. environmental, hormonal
8
Q
advantages of genetic testing
A
- empowers patients - allows them to make choices
- early screening programs can be offered
e. g. mammography - prophylactic surgery
9
Q
disadvantages of genetic testing
A
- the potential for discrimination e.g. medical insurance, employment
- additional stress with results
- guilt feelings in those not affected
- guilt feelings in those affected e.g. if already have children
10
Q
clinical suspicions
A
- family history
- young age of onset
- multiple cancers
11
Q
define what is meant by a condition not being fully penetrative
A
that because a mutation exists in a genotype doesn’t mean it will be expressed phenotypically
