Genetics: Genetics and Cancer

Question 1

what type of mutations is cancer largely caused by

Answer 1

post-zygotic - somatic mosaicism

Question 2

describe the heterogeneity of cancer

Answer 2

the same disease can be caused by many different types of mutations

Question 3

driver mutations

Answer 3

mutations that drive carcinogenesis

Question 4

passenger mutations

Answer 4

mutations that are accumulated as a result of cancers instability

Question 5

somatic mutations (in terms of cancer)

Answer 5

not inherited, mutations caused by carcinogenesis

Question 6

epigenetics

Answer 6

the study of mutations in the gene sequence but not in the DNA sequence

Question 7

what is methylation

Answer 7

prevents transcription by binding with histones

Question 8

where does hypomethylation occur

Answer 8

many tumour types

Question 9

where does hypermethylation occur

Answer 9

tumour suppressor genes

Question 10

what are oncogenes activated by

Answer 10

proto-oncogenes that are activated by point mutations, translocations or gene amplification leading to oncogenes gaining dominant control of function mutations

Question 11

as a result of mutations what might tumour cells possess

Answer 11

• own EC growth factors
• over expression of growth factor receptors
• continually active proteins that don’t require phosphorylation

Question 12

vemurafenib MoA

Answer 12

inhibits continually active proteins therefore stopping proliferation

Question 13

herceptin MoA

Answer 13

binds to receptors blocking proliferation signalling

Question 14

what is the Philidelphia Chromosome

Answer 14

translocation between 9 and 22 that can cause leukaemia

Question 15

what types of signal do normal cells rely on to regulate growth but cancer cells become unresponsive to

Answer 15

anti-growth signals

Question 16

are tumour suppressor mutations recessive or dominant

Answer 16

recessive

Question 17

how does hereditary Rb present

Answer 17

in babies with FHx

Question 18

how does sporatic Rb present

Answer 18

in older children with no FHx

Question 19

describe the 2 hit hypothesis

Answer 19

the first mutation increases cancer suscpetibility, the second leads to cancer

Question 20

tumour suppressor genes (6)

Answer 20

Rb 
BRCA 1
BRCA 2
p53 
PTEN 
APC

Question 21

what is the normal function of tumour suppressors

Answer 21

supress cell division

Question 22

what is the normal function of oncogenes

Answer 22

activates cell division

Question 23

are oncogene mutations recessive or dominant

Answer 23

dominant

Question 24

what types of mutations are tumour suppressor mutations normal caused by

Answer 24

point - deletions

Question 25

what types of mutations are oncogene mutations normal caused by

Answer 25

point, gene amplification, translocations

Question 26

why do cancer cells gain so many mutations

Answer 26

cancer cells become genetically unstable and so can acquire many mutations in order to continue growing

Question 27

what is and ‘oncogenic signature’

Answer 27

cancer characteristics are derived from their driver mutations in oncogenes rather than their tissue of origin

Question 28

what is Lynch syndrome

Answer 28

herediatry cancer caused by a mutation in the MLH1 repair gene

Question 29

are cancers multifactorial or mendelian

Answer 29

usually multifactorialm 5-10% mendelian

Question 30

what family features suggest an inheritable cancer susceptibility

Answer 30

• many 1st or 2nd relatives with cancer
• early age of onset
• many close relative with related cancer types
• bilateral tumours in paired organs
• tumours in 2 organ systems of 1 individual

Question 31

what does a positive result from genetic cancer testing entail

Answer 31

specific mutation associated with cancer that they were looking for was found

Question 32

what does a negative result from genetic cancer testing entail

Answer 32

the specific mutation associated with cancer was not found but individual may still develop cancer

Question 33

what does a variant of unknown significance result from genetic cancer testing entail

Answer 33

a variant was found however lab is uncertain if it is cancer causing or not