L13 - cancer epidemiology Flashcards

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1
Q

Why do we want to identify genes that are suceptability factors?

A

Understand mechanisms of the cancer, identify people at risk, personalise treatments

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2
Q

What is positional cloning?

A

Linkage analysis followed by cloning and sequencing. Assemble families with affected individuals and genotype these families to find associated mutated genes

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3
Q

What is a lod score?

A

A measure of how likely it is that a disease allele and marker are linked

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4
Q

What is BRCA1?

A

A multifunctional protein that is commonly mutated in breast cancer. It shares many features with BRCA2 e.g. 1 non-coding exon, large exon 11, 60% identity with the mRNA

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5
Q

What is the function of BRCA1?

A

Associates with a complex (MRN) that binds at sites of DNA damage (DSB) and initiates repair. It is phos by ATM

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6
Q

What is the purpose of SNP and GWAS analysis?

A

Allows identification of alleles that are commonly mutated in sporadic cancer

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7
Q

What is the spectrum of genetic risk?

A

Some genetic mutations cause an increased risk of cancer
Rare syndromes - high penetrance e.g. Rb, APC, XP - increase risk 1000 fold
Familial forms - breast and colon, increase risk 10-100 fold
Sporadic cases - breast, colon, increase risk 1-1.5 fold

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8
Q

What made researchers think that breast cancer may be familial?

A

Some families had a higher incidence of breast cancer. These families also showed an early onset, breast and ovarian cancer, bilateral cancers and higher frequency in males

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9
Q

What chromosome was breast cancer linked to?

A

23 multicase families - LOD score of 5.98 in families with marker at chr 17q12
Breast cancer linked to chr 17

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10
Q

What did Skolnick fail to show?

A

Linkage at the marker for chr 17 previously identified in breast cancer

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11
Q

How does the cell respond to DNA damage?

A

ATM phos in repsonse to DBS
ATM phosph MRE11/NBS1
MRE11/NBS1/RAD50 (MRN) complex binds at DSB and initiates DNA repair

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12
Q

What is the phenotype of mutations in ATM and NBS?

A

One of failing to signal DNA damage - increased sensitivity to ionising radiation, failure to induce p53, failure to stop DNA synthesis

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