Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Genomics SGUL Sem 3 > Genetics of Common Disease > Flashcards

Genetics of Common Disease Flashcards

1
Q

What is mutated in cystic fibrosis?

A

→ F delta 508
→ Phenylalanine codon is removed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the inheritance pattern like in Mendelian diseases?

A

→ Recessive loss of function
→ Autosomal dominant
→ X linked

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How can you measure intermediate phenotype?

A

Electrocardiogram

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the intermediate phenotype in people with sudden cardiac death?

A

→ Heart rate might be slower than it is supposed to be
→ Heart is larger than usual - cardiomyopathy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the relationship between conduction and heart size?

A

The larger the heart muscle the longer it takes for conduction because the surface area is larger

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does a quivering signal on an ECG look like and why?

A

→ Ventricular fibrillation
→ Heart muscle gets tired and there is no electrical output

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do the P wave and QRS wave mean?

A

→ P wave - going across the atria
→ QRS - going across the ventricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the QT interval associated with?

A

Highly associated with risk of sudden cardiac arrest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does it mean if the QT interval is longer?

A

Increased susceptibility of a heart attack

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why are twin studies used?

A

→ Twins are genetically identical
→ Non identical twins are not genetically identical but the environment is the same
→ This enables you to eliminate the environment as a confounding factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What percentage is the variation in heart rate due to genetics?

A

58%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What percentage is the variation in QRS down to genetics?

A

54%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does high heritability imply?

A

Strong resemblance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is concordance?

A

How similar a phenotype is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does it mean if there are big differences between MZ twins and DZ twins?

A

Trait is more genetic than environmental

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are SNPs?

A

→ Variations in a single nucleotide
→ DNA sequence variations that occur when a single nucleotide is altered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the most common form of variation in the genome?

A

SNPs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a genotype?

A

A pair of alleles at a locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a haplotype?

A

Sequence of alleles along a single chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a qualitative measure example?

A

→ Disease status
→ Presence or absence of congenital defect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is a quantitative measure example?

A

→ Blood glucose levels
→ % body fat
→ Heart rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the short term goal of genetic association studies?

A

Identifying genetic variants that explain differences in phenotype among individuals

23
Q

What is the long term goal of genetic association?

A

Inform the process of identifying and delivering better prevention and treatment strategies

24
Q

Why can the SNPs for cardiovascular disease not be in essential parts of the genome?

A

They do not manifest from birth

25
Q

What is the relationship between linkage disequilibrium and SNP distance?

A

Linkage disequilibrium between two SNPs decreases with physical distance

26
Q

When do you need fewer SNPs to capture variation?

A

When LD is strong

27
Q

Why are some variants not recombined?

A

The regions are physically together

28
Q

How many SNPs does an SNP chip have?

A

317,000 SNPs

29
Q

Describe how an SNP microarray works

A

→ Run 12 samples
→ Each of the wells has tags for 300,000 variants
→ They are stuck to the base of the chip
→ DNA is run across the chip
→ If the DNA has the variant it binds to it
→ Fluorescent dye binds

30
Q

What are the axes of the graph for testing genetic association?

A

→ X axis is genotype
→ Y axis is phenotype

31
Q

What do the dots on the manhattan plot represent?

A

A variant

32
Q

What do the peaks on the manhattan plot show?

A

Statistical test has a significant effect

33
Q

Why do you need a lot of people in a GWAS study?

A

If the genes are numerous and small in effect

34
Q

What are the 3 possibilities when finding a SNP associated with a disease?

A

→ Causal relationship between SNP and disease
→ Marker is in linkage disequilibrium with a causal locus
→ False positive

35
Q

How is the P value set?

A

→ 0.05/n
→ n is the number of tests

36
Q

What is linkage disequilibrium?

A

Linkage disequilibrium is the non-random association of alleles at different loci in a given population

37
Q

Define heritability

A

A measure of how well differences in people’s genes account for differences in their traits

38
Q

What does a heritability close to one indicate?

A

That almost all of the variability in a trait comes from genetic differences, with very little contribution from environmental factors

39
Q

What percentage of shared genetic variation for MZ, DZ, full siblings and half siblings?

A

MZ= 100
DZ=50
Full siblings= 50
Half siblings= 25

40
Q

Equation for heritability(h2)

A

h2 = 2 x (MZ correlation – DZ correlation)

41
Q

What does it mean for h2<0.5?

A

Environmental influences are more important than genetic component

42
Q

What does h2>0.8 suggest?

A

A trait highly influenced by genes

43
Q

On genetic susceptibility graph, what does the right side suggest?

A

→ There are more environmental influences involved
→ GWAS

44
Q

What does the left side suggest on a genetic susceptibility graph?

A

Linkage

45
Q

How else can you define linkage disequilibrium?

A

The difference between the observed frequency of a particular combination of alleles at two loci and the frequency expected for random association

46
Q

What happens to linkage disequilibrium between two SNP as physical distance increases?

A

Decreases with physical distance as more likely to have a recombination event between them

47
Q

What other factor affects LD?

A

Region of genome i.e. recombination hot spots

48
Q

What are the advantages of strong LD?

A

→ Need fewer SNPs to capture variation in a region
→ Cheaper and easier/quicker to analyse

49
Q

What is Bonferroni correction?

A

If the number of tests (SNPs genotyped) is n, we set the threshold to be 0.05/n so that we can avoid including false positives in our findings

50
Q

What are the three possibilities if a SNP is identified as significantly associated with disease?

A

→ A causal relationship between SNP and disease
→ Marker is in linkage disequilibrium with a causal locus
→ False positive

51
Q

What is the standard p-value for GWAS?

A

5 × 10−8

52
Q

Dizygotic twins, as with siblings in general, share on average 50% of their genome with each other. However dizygotic twins usually share a little bit more of their genetic variation than other types of siblings – why?

A

They also have the same shared in utero environment

53
Q

How do you measure genetic susceptibility?

A

Measure heritability

54
Q

What are the goals of GWAS?

A

→ Identify genetic regions that explain differences in phenotype among individuals in a study population
→ To identify genetic variants that can be measured to determine whether an individual is at higher risk of disease​
→ To identify potential drug targets to treat the disease

Genomics SGUL Sem 3 (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions