Genetics Predisposition to Cancer Flashcards

1
Q

What do a small proportions of cancers happen due to?

A

Increased inherited predisposition to cancer (genetic)

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2
Q

What are the 2 different kinds of gene mutations that cancer can arise from?

A

Somatic mutations

Germline mutations

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3
Q

Where to somatic mutations occur?

A

In somatic tissue, nongermline

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4
Q

What can you say about the inheritability of somatic and germline mutations?

A

Somatic cannot be inherited and germline can

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5
Q

Where are germline mutations present?

A

In egg or sperm

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6
Q
A
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7
Q

What are some genetic processes associated with cancer?

A

Oncogenes

Tumour suppresor genes

DNA damage response genes

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8
Q

What are proto-oncogenes?

A

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

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9
Q

What can mutations change into oncogenes and what does this do?

A

Proto-oncogenes which accerlerates cell division

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10
Q

What are tumour suppresor genes?

A

Genes that inhibit cell cycle or promotes apoptosis

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11
Q

What happens when tumour suppresor genes fail?

A

Cancer arises

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12
Q

What are DNA damage response genes?

A

Repair mechanism for DNA

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13
Q

What happens when DNA damage response genes fail?

A

Cancer arises due to speeding the accumulation of mutations in other critical genes

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14
Q

What is an example of a DNA damage response gene?

A

Mismatch repair genes (MMR genes)

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15
Q

What do mismatch repair (MMR) genes do?

A

Corrects errors that spontaneously occur during DNA replication like single base mismatches or short insertions and deletions

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16
Q

What does mismatch repair failure lead to?

A

Microsatellite instability (MSI) where there is the addition of nucleotide repeats, which is the phenotypic evidence that MMR is not functioning normally

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17
Q

What is microsatellite instability (MSI)?

A

Where there is an addition of nucleotide repeats, which is phenotypic evidents that mismatch repair genes (MMR) are not working correctly

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18
Q

What are the 3 kinds of tumours?

A

Benign

Malignant

Dysplastic

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19
Q

What are some properties of benign tumours?

A

Lack the ability to metastasize

Rarely or never become cancerous

Can cause negative health benefits due to pressure on other organs

20
Q

What are some properties of dysplastic tumours?

A

Benign but could progress to malignancy

Cells show abnormalities of appearance and cell maturation

21
Q

What is a unique property of malignant tumours?

A

Able to metastasize

22
Q

What are some other causes of cancer in relation to genes?

A

Autosomal recessive syndromes

Multiple modifier genes of lower genetic risk

23
Q

What are de novo mutations?

A

Occur in germ cells of parents with no family history of hereditary cancer syndrome

24
Q

What are de novo mutations common in?

A

Famial adenomatous polyposis

Multiple endocrine neoplasia 2B

Hereditary retinoblastoma

25
Q

What is hereditory retinoblastoma?

A

Most common eye tumour in children

26
Q

What is the type of inheritence of most cancer susceptability genes?

A

Dominant

27
Q

What are some risk factors for breast cancer?

A

Ageing

Family history

Late menopause

Early menarche

Nulliparty (condition where woman cannot give birth)

Estrogen use

Dietary factors (alcohol)

Lack of exercise

28
Q
A
29
Q

What is nulliparty?

A

Condition where woman cannot give birth

30
Q

What are some genes that increase hereditory susceptability to breast cancer?

A

BRCA1

BRCA2

TP53

PTEN

31
Q

Which of BRCA1 and BRCA2 increases the risk of breast cancer the most?

A

BRCA1 (20-40%) whereas BRCA2 is only 10-30%

32
Q

What are functions of the BRCA1 gene?

A

Checkpoint mediatory

DNA damage signalling and repair

Chromatin remodelling

Transcription

33
Q

What is the main function of the BRCA2 gene?

A

DNA repair by homologous recombination

34
Q

What do BRCA1 mutations increase the risk of?

A

Breast cancer (50-85%)

Second primary breast cancer (40-60%)

Ovarian cancer (15-45%)

Other cancers

35
Q

What do BRCA2 gene mutations increase the risk of?

A

Breast cancer (50-85%)

Ovarian cancer (10-20%)

Male breast cancer (6%)

Other cancers

36
Q

What are some risk factors for colorectal cancer?

A

Ageing

Personal history of colorectal cancer or adenomas

High fat, low fibre diet

Inflammatory bowel disease

Family history of colorectal cancer

37
Q

What are the 2 possible hereditary colorectal cancer syndromes?

A

Non-polyposis (few to no adenomas)

Polyposis (multiple adenomas)

38
Q

What is an example of a non-polyposis hereditary colorectal cancer?

A

HNPCC

39
Q

What are examples of polyposis hereditary colorectal cancers?

A

FAP

AFAP

MAP

40
Q

What are adenomas?

A

A beneign tumour formed from glandular structures in epithelial tissue

41
Q

What are some clinical features of HNPCC?

A

Early but variable age in CRC diagnosis (about 45 years)

Tumour site through colon rather than descending colon

42
Q

What is a clinical feature of familial adenomatous polyposis (FAP)?

A

Risk of extracolonic tumours (upper GI, thyroid, brain)

43
Q

What is a milder form of FAP?

A

Recessive MYH polyposis

44
Q

What do multiple modifier genes of lower genetic risk explain?

A

Families with history of cancer and no identified mutation

Different in cancer penetrance in families with the same mutation

45
Q

What can cancer risk for patients with FAP be managed by?

A

Surveillance

Surgery

Chemoprevention

46
Q

What are predictive gene tests used for?

A

To test who has genes that are associated with an increased risk in developing cancer

47
Q

What is it important to remember about inherited mutations causing cancer compared to other causes?

A

Most cancers are sparodic, with only a small proportion being due to inherited mutations