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Flashcards in Genetic Predisposition to Cancer Deck (25)
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1

From what types of mutations can cancer arise?

Somatic mutations (non-inheritable)
Germline mutations (egg/sperm; passed on; every cell in child)

2

What three types of genes can cause cancer?

Oncogenes

Tumour suppressor genes

DNA damage-response genes

3

How can oncogenes cause cancer?

- formed from proto-oncogenes
- accelerate cell division
- one mutation needed to lead to cancer

4

What is the function of proto-oncogenes?

Regulation of cell growth and differentiation

5

Give an example of an oncogene and a cancer it can cause

RET can lead to multiple endocrine neoplasia

6

What is the function of tumour suppressor genes?

- inhibit the cell cycle
- promote apoptosis

- mutations in both needed to lead to cancer ('two-hit hypothesis')

7

Give an example of a tumour suppressor gene and a cancer it can cause when defective

BRCA1 can lead to breast cancer
APC can lead to FAP

8

What is HNPCC?

Hereditary non-polyposis colorectal cancer

9

What is microsatellite instability?

Phenotype of DNA damage-response genes:

Microsatellite DNA fragments can be detected using PCR and indicate MMR isn't working properly

10

What is the function of DNA damage response genes?

- repair of DNA errors (during replication/synthesis...)

- mutations in both needed to lead to cancer

11

What is another name of DNA damage response genes?

MMR - mismatch repair genes

12

Give an example of a MMR/DNA damage-response gene and a cancer it can cause when defective

MLH1 can lead to HNPCC

13

Give two other possible genetic causes of cancer

- autosomal recessive disorders (e.g. MYH associated polyposis/MAP)

- multiple modifier genes of lower genetic risk

14

What are the features of heritable retinoblastoma?

- bilateral tumours
- 20% family history
- diagnosis at < 1 year old
- every cell has the mutation, therefore increased risk of osteosarcoma/melanoma

15

What are the features of non-heritable retinoblastoma?

- unilateral tumour
- no family history
- diagnosis at around 2 years old
- no increased risk of second primary cancers

16

Give some environmental risks of developing breast cancer

- ageing
- diet
- exercise
- family history...

17

Mutations in what genes can cause breast cancer?

- BRCA1
- BRCA2
- PTEN
- TP53
- many undiscovered genes

18

What is the normal function of BRCA1?

Codes for a tumour suppressor protein that repairs damaged DNA (example of a tumour suppressor gene)

19

What is the normal function of BRCA2?

DNA repair by homologous recombination

20

Give some risks of developing colorectal cancer (CRC)?

- ageing
- history of CRC/adenomas
- IBS
- high fat/low fibre diets

21

Name three types of colorectal polyposis

FAP (familial adenomatous polyposis)
AFAP (attenuated FAP)
MAP (MYH associated)

22

What are the clinical features of HNPCC?

- early diagnosis age
- tumours throughout colon
- extracolonic cancers also present

23

What are the clinical features of FAP?

- high penetrance for adenomas
- extracolonic cancers
- CHRPE often present
- untreated polyposis leads to a 100% chance of developing cancer

24

What are the clinical features of AFAP?

- later onset
- few adenomas
- no CHRPE present
- upper GI lesions
- associated with mutations in the APC gene

25

What is CHRPE?

Congenital hypertrophy of the retinal pigment epithelium