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Flashcards in genetic predisposition to cancer Deck (41):
1

what two types of gene mutations are there relating to cancer?

somatic and germline

2

what type of mutation causes cancer family syndromes?

germline

3

where are germline mutations present?

egg or sperm cells

4

what is a proto-oncogene?

normal gene that codes for proteins to regulate cell growth and differentiation

5

what is the effect of oncogenes?

accelerated cell division

6

what can change a proto oncogene into an oncogene?

mutation

7

how many mutations are sufficient for oncogenes to play a role in cancer development?

1

8

what are tumour suppressor genes?

cells "brakes" for cell growth

9

what are the effects of tumour suppression genes?

inhibit cell cycle
promote apoptosis

10

how many mutations must occur for tumour suppression genes to play a role in cancer development?

2

11

what do DNA damage-response genes do?

repair DNA

12

how many DNA damage response genes have to fail to cause cancer?

when both genes fail

13

what does mismatch repair failure lead to?

microsatellite instability

14

what is the effect of MMR?

corrects errors that spontaneously occur durinf DNA replication like single base mismatches or short insertions and deletions

15

what are created as a result of defective MMR?

novel microsatellites fragments called simple sequence repeats

16

what characterises a benign tumour?

tumour lacks the ability to metastasize

17

what characterises a dysplastic tumour?

benign tumour that has the potential to progress to malignancy

18

what would you see histologically in a dysplastic tumour?

abnormal cell appearance and cell maturation

19

what characterises a malignant tumour?

able to metastasize

20

what is a de novo mutation?

new mutation that occurs in germ cell of a patient

21

what is a retinoblastoma?

most common eye tumour in children

22

what is the difference between nonheritable and heritable retinoblastoma?

unilateral in nonheritable
usually bilateral in heritable
increased risk of second primary cancers in heritable
family history in around 20% of cases in heritable
heritable cancers typically present at a younger age

23

what are some risk factors for breast cancer?

ageing
family history
dietary factors
lack of exercise
estrogen use

24

what is the most common known gene that contributes to the development of breast cancer?

BRCA1

25

what are some functions of BRCA1

checkpoint mediator
DNA damage signalling and repair
chromatin remodelling
transcription

26

what are some functions of BRCA2?

DNA repair by homologous recombination

27

what is the risk of developing a BRCA1 associated cancer?

Breast - 50-85%
second primary breast cancer - 40-60%
ovarian cancer - 15-45%

28

what is the risk of developing a BRCA2 associated cancer?

breast cancer: 50-85%
male breast cancer: 6%
ovarian cancer: 10-20%

29

what are some risk factors for colorectal cancer?

ageing
personal history
high fat low fibre diet
IBS
family history of CRC

30

what are some hereditary colorectal cancer syndromes?

non-polyposis
polyposis

31

what is an example of a non-polyposis CRC syndrome?

hereditary non-polyposis colon cancer- HNPCC

32

what are some example of polyposis CRC syndromes?

FAP - severe colonic polyposis
AFAP - less severe colonic polyposis
MAP - varying degrees of colonic polyposiss

33

what does FAP stand for?

familial adenomatous polyposis

34

what are some clinical features of HNPCC?

tumour site throughout colon rather than descending colon
can lead to the development of extracolonic cancers (endometrium, ovary)

35

what are some clinical features of FAP?

over 90% penetrance for adenomas
risk of extracolonic tumours
CHRPE
untreated polyposis leads to 100% risk of cancer

36

what does CHRPE stand for?

congenital hypertrophy of the retinal pigment epithelium

37

what are some clinical features of AFAP?

later onset
few colonic adenomas
not associated with CHRPE
upper GI lesions
associated with mutations at the 5' and 3' ends of APC gene

38

what can oppose the effect of inherited cancer genes?

multiple modifier genes of lower gentic risk

39

how are adenomatous polyposis syndromes managed?

surveillance
surgery
chemoprevention

40

are the majority of cancers sporadic or inherited?

sporadic

41

what is the effect of an inherited mutation?

increased PREDISPOSITION to cancer