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Genetics Of Complex Disease > L4 Study Designs > Flashcards

L4 Study Designs Flashcards

1
Q

What are the 2 purposes of studies

A

See if it is inheritable/a genetic component eg via twins

See what the association is

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2
Q

Do alleles have to be single bases or snps

A

No can be sequences of eg cnvs or inversions

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3
Q

How do children of same parents differs so much

A

Homologous recombination some have different alleles from diff parents

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4
Q

Why is the phenotype and genotype in complex called a probabilistic relationship

A

Not 100% penetrance

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5
Q

Does having both copies of a risk allele cause you to have disease in complex

A

No

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6
Q

What is the probability represented as (2 ways)

A

Odds ratio and genotype relative risk

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7
Q

How to calculate genotype rr

A

Baseline risk of disease x number of the risk alleles (0-2)

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8
Q

Where are mutations/snps often in complex disease located

A

Non coding regions therefore affecting gene exp levels more then function

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9
Q

How do you recognise recessive pattern in a pedigree

A

1 generation usually affected and seen in consanguineous families ie inbreeding

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10
Q

What are family studies used for

A

Detect a genetic contribution to a disease

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11
Q

What doesn’t family studies do so what do you have to do after

A

Doesn’t find causal variant so need to do functional tests on model organisms eg via crispr ko or on cell thpes

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12
Q

Do family studies work better for Mendelian disease

A

Yea

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13
Q

What type of analysis is done on family studies

A

Segregation analysis

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14
Q

What does this do

A

Estimates things like gene freq, shared environmental effects, penetrances in the family which best explain the inheritance pattern

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15
Q

Does segregation analysis allow to study polygenic inheritance

A

Yes to an extent

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16
Q

How is twin studies good for complex to see if there is a genetic determinant

A

Studies concordance rates between mz and dz since shared environments. If higher concordance in the mz means it is likely genetic factors

17
Q

What does recurrent risk do

A

Another way to assess genetic contribution to a disease

18
Q

What does rr mean

A

Probability of the disease recurring in family

19
Q

What does proband mean

A

The person who first had the disease in the family

20
Q

Which 3 people related to proband can a recurrence risk be calculated for

A

Sibling Ks
Offspring Ko
Mz twin Kmz

21
Q

What is the recurrence ratio

A

Ks/k (whole popn risk)

22
Q

If ks is 3 what does this mean

A

3 fold more likely than rest of popn

23
Q

Whcih study is done mainly for Mendelian diseases to localise the genetic contributions

A

Parametric linkage analysis

24
Q

What does this entail

A

Using large pedigrees and obtaining dna from then to genotype specific genetic marker loci

25
Q

What does parametric linkage analysis allow to measure

A

Co segregation of alleles (in a haplotype)

To see if the allele locus you’re testing is linked to the locus associated with disease

26
Q

What is the actual hypothesis of linkage analysis

A

Studying if the locus is linked to a disease locus (not trying to prove it is causing the disease)

27
Q

Why do you not need to genotype the disease locus in the pedigree in linkage analysis

A

Can infer patterns eg dominance = Atleast 1 copy , if recessive it means 2 copies and both parents carriers

28
Q

What is used on complex disorders which is similar

A

Non parametric linkage analysis

29
Q

What does this measure

A

If 2 affected siblings affected for example share genetic material in common from their parents/ancestors

30
Q

Linkage xant be done on non related people to find variant, so what is done ie using case control

A

Association studies

31
Q

Do you always get a direct causal relationship in association studies

A

No, the allele/ variant you find might just be linked to the causal variant , which is still good as it narrows the genomic region it can be in

32
Q

What test of correlation is done if an allele is seen in higher freq in cases

A

X2 test for indep (chi)

33
Q

Can association studies be done on family pedigrees

A

Yes you can investigate high risk allele transmission

34
Q

What type of sequencing/genotyping done on candidate approach

A

Targeted sequencing or snp genotyping eg sequenom

35
Q

How has sequencing in gwas developed

A

Started from micro satellite markers now can use dense microarray snp genotyping up to 5 mill snps

36
Q

Why is it not useful to sequence whole genome

A

99% identical

37
Q

Why does gwas fundings usually have no predictive value in disease

A

Small odds ratios eg 1.6

Genetics Of Complex Disease (17 decks)

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