Cancer, genetics and inherited syndromes Flashcards

1
Q

Knudson’s two hit model of oncogenesis

A

can be hereditary or non-hereditary cancer

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1
Q

Non hereditary cancer

A

needs to have 2 hits so normal chromosomes , normal genes -1 mutation then another mutation which leads to cancer.

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2
Q

Hereditary cancer

A

individual is more susceptible to the disease as every cell in the body has the copy- only 1 sporadic

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3
Q

Sporadic cancer

A

are changes that happen during life

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4
Q

the mutation in hereditary is already there, what can this lead to?

A

risk is higher for the second hit to happen

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5
Q

retinoblastoma

A

aggressive eye cancer

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6
Q

what mutation is retinoblastoma initiated by?

A

RB1 tumour suppressor gene- located on long arm of chromosome 13q14

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7
Q

sign of retinoblastoma

A

leucorcia (abnormal white reflection from retina)

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8
Q

what does the RB1 gene contribute to?

A

the regulation of the cell cycle-return of the blastoma cells which binds to transcription factors called EF2 and stops activity of transcription factor

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9
Q

when the activity of transcription factor stops what happens?

A

stops the growth and puts break on the cell cycle-when phosphorylated by cyclins it releases the transcription factor and cell progression is allowed

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10
Q

what happens once phosphorylated and cyclins adds phosphate?

A

releases the transcription factor so cell growth continues and cell cycle continues when its mutated and cannot bind that’s why cells grow more

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11
Q

what 2 genes is cancer caused by?

A

1.BCRAC1
2.BRCA2

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12
Q

what are the genes BCRAC1 or BRCA2(tumour suppressor gene) involved in?

A

repair of the DNA and rest is sporadic

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13
Q

non homologous joining pathway, single stranded annealing pathway

A

both prone 2 errors
If there is a homologous chromosome already, they will look at that and repair the other one according to that – the pathway matches the sequence and repair it

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14
Q

2 main types of familial colorectal cancer

A

1.Familial adenomatous polyposis(FAP
2.Hereditary non-polyposis colorectal cancer(HNPCC) or lynch syndrome

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15
Q

what is Familial adenomatous polyposis(FAP?

A

has lots of lesions in the phenotypes
-gene involved EPC- is mutated in FAP cancer

16
Q

what is the location of FAP cancer?

A

located left side of colon accounts for 1% of cancer

17
Q

which chromosome is FAP cancer located?

A

chromosome 5

18
Q

in FAP cancer what are the 3 things that chromosome 5 regulate?

A

1.cell proliferation
2. adhesion
3.the mutation can also be seen in sporadic cases

19
Q

what is the age of onset for FAP cancer?

A

20-25

20
Q

Hereditary non-polyposis colorectal cancer(HNPCC) or Lynch syndrome -what happens to the mutations?

A

DNA mismatch repair proteins

21
Q

what is the age of onset for HNPCC?

A

40-50

22
Q

What is the location of HNPCC?

A

this occurs at the right side of the colon

23
Q

what are the mismatch repair proteins in HNPCC?

A

spell checkers

24
Q

what protein will DNA damage pathway end up with?

A

microsatellites instability

25
Q

what is microsatellites instability?

A

produce alternative sequences which are not present in original sequence , there would be a mutation in mismatched proteins so spellchecker cannot spell check what has been written which ends up with microsatellites

26
Q

what is genetic testing ?

A

since there are germline changes it can be easily suspect change in the family or younger family members are affected , NHS labs offer genetic testing
Once the gene is identified they can offer other family members with genetic testing’sBRAC genes are big genes so take time to extract the DNA- process can take up to 3 months

27
Q

Genetic counselling

A

gives patients right information , and what services would be beneficial for them