Genetic Cancer Predisposition Flashcards

1
Q

What is a germline mutation

A

Gene change reproductive cell (egg or sperm)
Becomes incorporated into DNA of every cell in body of offspring

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2
Q

What kind of cancer does germline mutation cause?

A

Cancer Syndrome
Family cancer syndrome

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3
Q

what 3 types of genes are involved in pre-disposition to cancer?

A

Oncogenes
Tumour-supressor Genes
DNA damage-response genes

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4
Q

What is a proto-oncogene?

A

A normal gene that codes for proteins which regulate cell growth/differentiation

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5
Q

What is an oncogene?

A

Mutated proto-oncogene

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6
Q

What does an oncogene do

A

Promote cell division
Promote cell proliferation
Causes cancer

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7
Q

What do tumour supressor genes do?

A

Inhibit cell cycle
Promote apoptosis

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8
Q

How many mutations are required to disable tumour supressor genes?

A

2, one for each “brake”

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9
Q

Explain the two-hit hypothesis?

A

Two mutations that disable 2 tumour suppressor genes, leading to cancer
1st mutation disables brake 1 (susceptible carrier)
2nd mutation disables 2nd brake (leads to canceR)

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10
Q

What is a cell called with one tumour supressor gene disabled?

A

A susceptible carrier

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11
Q

What are DNA damage response genes?

A

DNA repair mechanisms

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12
Q

How many genes are invlved in DNA repair?

A

2

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13
Q

How does the failure of DNA damage response genes lead to cancer?

A

Both genes fail
Accumulation of mutations in other critical genes speeds up

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14
Q

What is the MMR gene?

A

Mismatch repair gene.

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15
Q

What does a normal MMR gene do?

A

Repairs basic mutations

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16
Q

What does a defective MMR gene do?

A

Doesn’t repair mutations
Worsens mutation
(e.g.instead of fixing mutated base it alters the complementary one to match)

17
Q

What does a defective Mismatch repair gene lead to?

A

Micro satellite Instability (MSI)

18
Q

Give an example of a dominant inherited cancer syndrome cause by an oncogene?

A

MEN2 (multiple endocrine neoplasia)
Caused by RET gene

19
Q

Give an example of a dominatly inherited cancer syndrome caused by defective tumour supressor genes?

A

Breast/ovarian cancer more likely in people with defective BRCA1 or BRCA2 genes

20
Q

Example of cancer syndrome caused by defective DNA repair genes?

A

Lynch syndrome (HPNCC) gives people higher risk of cancers of digestive & gynaecological tracts

21
Q

What DNA repair genes are defective in Lynch syndrome?

A

MLH1
MSH2
‘Other’

22
Q

How else do genetics contribute to/cause cancer?

A

Autosomal Recessive Syndromes
Multiple modifier genes of lower genetic risk affect expression of more important genes

23
Q

Whats the name for new mutations?

A

De novo mutations

24
Q

Where do De Novo mutaions occur?

A

Parent germ cell

25
Q

Why do inherited cancer susceptibility genes appear to skip generation?

A

Mainly dominant with incomplete penetrance

26
Q

What are specifc risk factors for Breast Cancer?

A

Age
Early puberty
Late menopause
Using oestrogen

27
Q

What are specific risk factors for Colorectal cancer(CRC)?

A

High-fat Low-Fibre diets
Inflammatory Bowel Disease
Family history of CRC.

28
Q

How does an adenoma become a carcinoma?

A

Normal epithelium gains APC mutation
Hyper proliferative epithelium has K ras mutation
Adenoma experieicnes p53 mutation
Carcinoma produced

29
Q

What does polyposis mean?

A

Formation of multiple Adenomas

30
Q

What is FAP?

A

Familial Adenomatous Polyposis
Hereditary condition leading to formation of multiple adenomas in large intestine that can lead to colorectal cancer

31
Q

What is HNPCC?

A

Hereditary Non-Polyposis Colorectal Cancer
Hereditary condition leading to colorectal cancer with no adenomas

32
Q

What is the difference between genome & exome sequencing?

A

Genome sequencing - entire genome
Exome sequencing - only exon sequencing, no introns

33
Q

What is Microsatellite Instability?

A

Condition caused by defective MMR genes
Genes are hypermutatable
Multiple mutated nucleotides form microsatellite fragments