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BIOL0027 > GWAS and Human Ageing > Flashcards

GWAS and Human Ageing Flashcards

1
Q

Is breast cancer polygenic or monogenic?

A

Polygenic

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2
Q

What are the characteristics of the most common breast cancer susceptibility variants identified by GWAS?

A

Intronic

Regulatory - affect protein expression levels

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3
Q

What are cross-disease heritability correlations?

A

Comparing gene association pattern of one disease with pattern for another

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4
Q

What does high genetic correlation for 2 diseases mean?

A

Shared genetic risk factors

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5
Q

What is the key role of telomeres?

A

Maintain genome stability and integrity

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6
Q

What is required for telomere maintenance?

A

Telomerase

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7
Q

What is telomerase reverse transcriptase (TERT)?

A

Subunit of telomerase

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8
Q

What is the effect of TERT SNPs?

A

Decrease TERT expression level
Loss of telomere function
Genomic instability
Increases risk of certain cancers

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9
Q

How might age increase cancer risk?

A

TERT and telomere length decrease with age

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10
Q

What do most gene variants associated with coronary artery disease by GWAS affect?

A

Gene expression regulation

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11
Q

What is pleiotropy?

A

Single gene affects multiple traits

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12
Q

What did the comparison of menopause age variant frequency patterns to a neutral line find and what does this suggest?

A

Multiple variants for early menopause at ‘lower than neutral’ frequency
Strong polygenic selection against early menopause variants

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13
Q

Why might there be an antagonistic relationship between CAD and reproductive success?

A

May have genetic predisposition to CAD - same variants have positive effect on reproductive traits

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14
Q

What are the 5 outcomes that are used as indirect measures of ageing?

A

Long-livedness
Lifespan
Parental lifespan - link to offspring genetics
Healthspan - age before first chronic disease
Age-related diseases and traits

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15
Q

What did an genetic correlation study between multiple complex traits with healthspan find?

A

Negative correlation of lifespan with parental age at death, smoking cessation
Positive cessation of lifespan with CAD susceptibility, type 2 diabetes

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16
Q

What is a DNA methylation (DNAm) age?

A

‘Epigenetic clock’

Some methylation patterns closely linked to age

17
Q

What is usually the relationship between DNAm and chronological age?

A

Highly correlated

18
Q

What is epigenetic age acceleration (EAA) and what is it linked to?

A

Epigenetic clock ahead of chronological age

Higher all-cause mortality risk

19
Q

What is DNAm not correlated with?

A

Leukocyte telomere length (LTL) - mitotic clock

20
Q

What is intrinsic EAA?

A

Leukocyte DNA epigenome

Independent of age-related changes in blood cell composition

21
Q

What is extrinsic EAA?

A

Leukocyte DNA epigenome

Considers age-related changes in blood cell composition

22
Q

In which gene is there an SNP association between IEAA and LTL and what does this suggest?

A

TERT

Key role for TERT in regulating epigenetic clock

23
Q

According to the omnigenic model, what are the 3 types of genes and their roles?

A

Core genes - direct roles in disease
Peripheral genes - all other expressed genes - c an trans-regulate core genes
Genes expressed in irrelevant cell types - no contribution to heritability

24
Q

What does the omnigenic model suggest?

A

Most phenotypic variance due to regulatory variance in peripheral genes
Many peripheral genes with weak effects

25
Q

What is cis-regulation of core genes?

A

Intronic regions control transcription of neighbouring genes

26
Q

What is trans-regulation of core genes?

A

Peripheral genes control transcription of faraway genes

27
Q

Is most heritability due to cis or trans effects?

A

Trans - SNPs outside core pathways

28
Q

What are expression quantitative trait loci (eQTLs)?

A

mRNA/protein levels from single gene

29
Q

What are cis eQTLs?

A

eQTLs that map to location of gene of origin

30
Q

What are trans eQTLs?

A

eQTLs that map far from location of gene of origin

31
Q

What is the relationship between earlier menarche/menopause ages and IEAA?

A

Earlier menarche/menopause ages cause increased IEAA

32
Q

What is the effect size of trans eQTL SNPs on expression level and what does this suggest?

A

Smaller than cis eQTLs

Typical gene has many weak trans-regulators

33
Q

What is the significance of gene regulatory networks being interconnected?

A

All genes expressed in disease-relevant cells can affect functions of core disease-related genes

BIOL0027 (20 decks)

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