Flashcards in Genetic predisposition to cancer Deck (36)
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1
What do most cancers arise from
Genetic mutations either sporadic or inherited
2
What kind of cancer mutation is non inheritable
somatic
3
What causes germ-line mutations
Hereditary -present in egg or sperm of parents
4
What are tumours
clonal expansions
5
What are the three genetic processes associated with cancer syndromes
Oncogenes
Tumour suppressor genes
DNA damage-response genes
6
What are oncogenes
Mutated proto-oncogens that accelerate cell division
7
How many mutations are needed to active oncogenes
1
8
What is the role tumour suppressor genes
Inhibit cell growth
promote apoptosis
Cells breaks
9
When does cancer arrive with tumour suppressor genes
when both tumour suppressor genes fail
10
Where does the two hit in tumour suppressor genes occur resulting from carrier to cancer
first - germ line (carrier)
second - tumour formation
11
What do DNA damage-response genes do
The repair mechanics for DNA
12
When does cancer arrive from DNA damage-response genes
both genes fail, speeding the accumulation of mutations in other critical genes
13
Give an example of a DNA damage response gene MMR
failure to mismatch due to single base mismatches or short insertions and deletions leads to accumulation of nucleotide repeats - Microsatellite instability
14
What is the evidence that DNA damage response genes aren't working
Microsatellite instability
15
What is de novo mutations
mutations occurring in there germ line of parents with no family history of hereditary cancer
16
How do we look for inherited cancers
family history
17
What are most cancer susceptible genes
autosomal dominant with incomplete penetrance - therefore have genes but do not show the symptoms
18
What is sporadic cancer
cancer by chance
19
If tumours are heritable they are usually bilateral with increases the risk of what and why
secondary primer
because every cell carries the mutation
20
How is Retinoblastoma cancer occur
due to heritable or non heritable tumour supressor genes
21
What are the risks factors for breast cancer
Ageing
Family history
Hormones - late menopause/pill/HRT
Dietary factors
Lack of exercise
22
What is the most likely and second most likely gene to causes breast cancer and by what mutation
BRCA 1 then BRCA2
spordic
23
What is BRCA1 genes functions
Checkpoint mediator
DNA damage signalling and repair
Chromatin remodelling (inactive Xchromosome)
24
What is BRCA2s functions
DNA repair by HR (homologous recombination)
25
What else can BRCA1/2genes cause
Secondary breast cancer
Ovarian cancer
Male breast cancer
26
What cancer conditions can arise from tumour suppressor gene
Breast cancer
ovarian cancer
Retinoblastoma
27
What are the risk factors for colorectal cancer
Ageing
Personal history of CRC or adenomas
High-fat, low-fibre diet
Inflammatory bowel disease
Family history of CRC
28
How does Hereditary nonpolyposis colorectal cancer occur
DNA Mismatch Repair of HNPCC gene
29
what does polyposis and non polyposis mean
multiple adenomas present
No adenomas - but there is a risk of development
30
Lynch syndrome aka HNPCC is what
autosomal dominant genetic condition that has a high risk of colon cancer
31
What gene causes severe polyposis in colon cancer
FAP - familial adenomatous polyposis
32
What is clinical features of HNPCC
Tumor site throughout colon rather than descending colon
Extracolonic cancers: endometrium, ovary, stomach, urinary tract, small bowel, bile ducts, sebaceous skin tumors
33
Clinical Features of FAP
Estimated penetrance for adenomas >90%
Risk of extracolonic tumors
Untreated polyposis leads to 100% risk of cancer
34
What is autosomal recessive cancer syndrome and example
need to Inherit copies in both parents to show symptoms e.g. MYH polyposis
35
What explains a family with history of cancer but no identified mutation
Multiple modifier genes of lower genetic risk
36
