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SOC > Gene-Environment interplay > Flashcards

Gene-Environment interplay Flashcards

1
Q

What are the 3 main types of Gene-environment correlation (rGE)?

A
  • Passive
  • Active
  • Evocative
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2
Q

We measure rGE using a range of designs

Name 3?

A
  • Twin studies
  • Adoption studies
  • Molecular genetic studies
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3
Q

Explain HOW passive rGe can be detected?

and what association does it refer to?

A
  • can be detected by comparing correlations between family environment and children’s traits in adoptive and non-adoptive families
  • refers to association between genotypes a child inherits from their parents and the family environment
  • can only occur between individuals who share both the family environment and genetic material
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4
Q

Passive rGE is implied if the correlation between family environment and the child’s trait is greater in non-adoptive than adoptive families.

True or False?

A

TRUE

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5
Q

The adoption design is not able to assess what 2 things?

A
  • evocative rGE (an association between genetically influenced behaviour and the way people react)
  • active rGE (when individuals select, create and modify their environmental experiences based on genetic dispositions)
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6
Q

Evidence was found for evocative gene-environment correlation for antisocial behaviour in adolescence.

true or false?

A

TRUE

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7
Q

What is the difference between twin studies and GCTA ?

A 
Twin studies 
  • Family-based
• Depend on special samples, i.e. twins
• Involve a few hundreds of pairs of
participants.
• Require no DNA
GCTA
• Population-based
• Can use any sample of unrelated individuals • Can involve thousands of people
• Requires DNA - genetic influences
measured using SNPS • Needs GWA data
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8
Q

Gene-environment correlation (rGE) is of interest for several reasons
name 3?

A
  • It can bias heritability estimates of traits associated with the environment in question.
  • To interpret heritability estimates, it is important to understand how rGE can affect them.
  • rGE can have implications for our understanding of relationships between environmental variables and traits.
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9
Q

The most common way to estimate heritability is comparing correlations between MZ twins with that between DZ twins.

true or false?

A

TRUE

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10
Q

active or evocative gene-environment correlation occurs leading to?

A
  • increased genetic resemblance between MZ twins will lead them to seek similar environments, making MZ twins more alike than DZ twins
  • increases A, the heritability estimate
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11
Q

Passive rGE leads to?

A

all children biologically related to their parent inherit an environment that correlates with their genome

true for all twins, MZ or DZ, who will become more alike

increases resemblance of DZ twins relative to MZ twins

increases C, shared environment estimate

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12
Q

If passive rGE is more important during infancy and childhood, and active rGE becomes more important as children develop, what would you expect to happen?

A

Heritability to increase over development, with the relative importance of the shared environment decreasing

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13
Q

If passive rGE is more important during infancy and childhood, and active rGE becomes more important as children develop, what would you expect to happen?

A

Heritability to increase over development, with the relative importance of the shared environment decreasing

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14
Q

Passive rGE makes MZ and DZ twins more alike, so increases estimates of shared environment.

true or false?

A

TRUE

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15
Q

Active rGE is driven by the child’s genes so makes MZ twins more alike than DZ twins, increasing heritability.

True or False?

A

TRUE

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16
Q

Many twin studies support the notion that different forms of rGE are important at different stages of development.
True or False?

A

TRUE

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17
Q

In childhood, large C combined with small A suggests that MZ and DZ twin pairs were equally similar.

This aligns with the notion of passive rGE being important for childhood depression

True or False?

A

TRUE

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18
Q

passive rGE is important in?

A

Childhood

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19
Q

active rGE becomes more important when?

A

In adolescence

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20
Q

As children age, they may seek out environments that suit their genetically influenced ‘g’.

True or false?

A

TRUE

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21
Q

It is not possible to use twin studies to investigate correlations between environmental variables and behavioural traits.

True or false?

A

FALSE

It is possible to use twin studies to investigate correlations between environmental variables and behavioural traits.

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22
Q

What is maternal negativity?

A
  • negative maternal behaviours directed towards a child
  • is associated with adolescent antisocial behaviour
  • often considered an environmental risk factor - external to the individual, predicts a particular outcome
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23
Q

Putative environmental variables are often heritable. As such, genes associated with the environment might?

A

Overlap

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24
Q

Maternal negativity might correlate with adolescent antisocial behaviours because the same genes are involved.

True or false?

A

TRUE

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25
Q

Genome-wide Complex Trait Analysis estimates what?

A

Heritability using unrelated singletons

26
Q

For some environmental variables, it is not possible to calculate heritability using the twin method.

Why is this so?

A

Some variables will always be the same for twin pairs regardless of zygosity

27
Q

Because GCTA does not use related individuals, it is possible to calculate the heritability of such environmental variables.

True or false?

A

TRUE

28
Q

It has been shown that family socioeconomic status is heritable, and genes associated with socioeconomic status also associate with what?

A

children’s intelligence

educational achievement

29
Q

Many putative environmental variables we have discussed are in fact parental variables.

The fact that parent and child are related to one another means that rGE is always possible for any association between parent and child.

True or false?

A

TRUE

30
Q

Parents and children share DNA, so any parental risk factor could associate with offspring outcomes because?

A

parenting directly influences child development

and/or

parents and children share genes associated with both parenting and child outcome

31
Q

If the child’s genes correlate with the parenting, it is difficult to identify whether parenting is a risk factor.

True or false?

A

TRUE

32
Q

Are there designs that allow us to disentangle genetic transmission from the possibility of environmental effect?

A

YES

33
Q

A research design for studying associations between parent and offspring. It involves using samples of twin pairs where each twin has a child.

What can this study design be used to study? 6 things

A
  • intergenerational transmission of mental health problems
  • effects of parenting style on child development
  • effects of home environment
  • effects of in-utero environment
  • impact of adolescent motherhood
  • effects of family composition
34
Q

What are avuncular correlations?

A

aunt/uncle and niece/nephew correlations in mz and dz twins

35
Q

Cousins share how much of their genetic variance?

A

12 and 1/2 of their genetic variance

36
Q

Let’s imagine there are two brothers. They will share on average what percentage of segregating genes?

A

50 %

37
Q

Now, imagine they each have a child. They will pass on what % of DNA on to their child?

A

50%

38
Q

To calculate the genetic relatedness between brother 2 and child 1, the avuncular association, we can do what?

A

multiply the paths that connect them

the parent-child path and the brother-brother path– that is, 0.50 times 0.50 equals 0.25

So uncle and niece or nephew share 25% of their segregating genes.

39
Q

What do path tracing rules allow?

A

allow us to calculate the relatedness between cousins

in this case, 0.5 by 0.5 by 0.5. This gives us 0.125.

So cousins share 12 and 1/2% of their segregating genes on average

40
Q

However, things are slightly different when it comes to monozygotic twins. When monozygotic twins have children, those children are as genetically related to their aunt or their uncle as they are to their own parent

True or False?

A

TRUE

41
Q

In effect, they receive half of their genes from both their parent and his or her co-twin, but they receive their rearing environment from the parent only

True or false?

A

TRUE

42
Q

So if parent-child correlations are larger than avuncular correlations, then this implies a role for?

A

a rearing environment in explaining intergenerational associations

43
Q

Monozygotic avuncular correlations involve a genetic association of?

A

0.5

44
Q

Dizygotic avuncular correlations involve a genetic association of?

A

0.25

45
Q

the association between parental depression and offspring internalizing is not attributable to genetic transmission, and instead involves exposure.

true or false?

A

TRUE

46
Q

Topic 3: Investigating gene-environment interaction

A
47
Q

Define gene-environment interaction?

A

Interactions refers to the differential effect of one variable at different levels of another variable.

48
Q

When do these interactions occur?

A

occur when environmental risks change as a function of genetic risk - or genetic risks are only expressed in certain environments.

49
Q

Genetic effects might only show up in certain environments.

An environmental influence might only have an impact when it’s combined with specific genetic risk.

TRUE OR FALSE?

A

TRUE

50
Q

Do genetic and environmental influences combine in an additive fashion?

A

NO

51
Q

What is Phenylketonuria (PKU)?

A

Phenylketonuria (PKU) is a rare genetic disorder that leaves individuals unable to metabolise phenylalanine.

Individuals must have two copies of the PKU allele to be affected.

Carriers of the PKU allele have a 1⁄4 chance of having an affected child.

PKU can lead to serious intellectual disability as it causes phenylalanine to build up in the blood and brain.

52
Q

The effects of the PKU allele can be ameliorated by what?

A

changing the environment – an example of GxE.

53
Q

Why does this occur?

A

This is because the genetic effect only occurs in the presence of the amino acid and its negative effects only occur in the presence of the PKU allele.

54
Q

If PKU is diagnosed at birth what can be done?

A

the affected individuals can be put on a special low- protein diet which reduces the levels of phenylalanine in the body and prevents brain damage.

55
Q

What are the symptoms of PKU?

A

PKU doesn’t usually cause any symptoms if treatment is started early.

However, if not treated early it may lead to abnormal brain development which in return would cause cognitive impairment

56
Q

The exact implications of ignoring gene environment interactions depends on the type of environmental influence the genetic factors interact with.

AxC= ?

A

A

57
Q

AxE=

A

E

58
Q

The simplest way to look at whether heritability changes as a function of environment is?

A

to see whether A, C and E are different in different environments.

59
Q

Twin research into GxE typically uses a structural equation model that allows the environmental moderator to have a main effect on the trait as well as a moderating effect on any or all of the residual A, C, E components of the trait.

True or False?

A

TRUE

60
Q

Name 5 continuous variables?

A

Age

Socioeconomic status

Regional alcohol sales

Parental warmth

Family wellbeing

61
Q

Do genetic influences on depression change as a consequence of the environment?

A

Yes, there are significant GxE with depressive symptoms and family conflict.

62
Q

Molecular genetic approaches and GxE

What are the 2 approaches?

A

Candidate gene studies - focus on a single genetic variant

Genome wide-approach - information from the whole genome

SOC (5 decks)

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