Genetic Cancer Predisposition Flashcards

1
Q

What kind of cancer does germline mutation cause?

A

Cancer Syndrome or family cancer syndrome

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2
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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3
Q

What is a proto-oncogene?

A

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

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4
Q

How does a proto-oncogene mutate?

A

To an oncogene

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5
Q

What is an oncogene?

A

The mutated form of a proto-oncogene

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6
Q

/What does an oncogene do

A

Oncogenes promote cell division, causing cancer when stuck in the “on” mode.

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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

The two mutations that disable the 2 tumour supressor 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

The repair mechanisms of DNA

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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

When both genes fail the 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

It either doesnt repair the mutations or worsens them.
E.g. instead of fixing a mutated base it alters the complementary one to match.

17
Q

What does a defective Mismatch repair gene lead to?

A

Microsatellite Instability. (MSI)

18
Q

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

A

MEN2 (multiple endocrine neoplasia) caused by the RET gene

19
Q

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

A

Breast/ovarian cancer are far 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 a much higher risk of cancers of digestive & gynaecologic tracts.

21
Q

What DNA repair genes are defective in Lynch syndrome?

A

MLH1 & MSH2 amonst others.

22
Q

How else do genetics contribute to/cause cancer?

A
  • Autosomal Recessive Syndromes
  • Multiple modifier genes of lower genetic risk affect how much more important genes are expressed.
23
Q

Whats the fancy fucker name for new mutations?

A

De novo mutations

24
Q

Where do De Novo mutaions occur?

A

In the parent germ cell

25
Q

Why do inherited cancer susceptibility genes appear to skip generation?

A

Because they are 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 hisotry of CRC.

28
Q

How does an adenoma become a carcinoma?

A

-> Normal epithelium gains APC mutation
-> Hyperproliferative 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 the large intestine that can lead to colorectal cancer.

31
Q

What is HNPCC?

A

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

32
Q

What is the difference between genome & exome sequencing?

A

Exome sequencing only sequences the exons, ignoring the interons.

33
Q

What is Microsatellite Instability?

A

A condition caused by defective MMR genes where yours genes are hypermutatable. multiple mutated nucleotides form microsatellite fragments