multifactorial

Question 1

distinct variant of a phenotype characteristics that may be inherited

Answer 1

trait

Question 2

results from the influence of only one gene

Answer 2

monogenic trait

Question 3

results from the combined influence of multiple genes

Answer 3

polygenic trait

Question 4

results from the combined influence of multiple genes and environmental factors

Answer 4

multifactorial trait

Question 5

combined contribution of genes and environmental factors in the causation of a particular disease or trait

Answer 5

multifactorial inheritance

Question 6

(2) multifactorial traits

Answer 6

(1) Quantitative

(2) threshold

Question 7

continuous range of measurement, numerical scale, follows a normal or bell-shaped distribution in populations

Answer 7

Quantitative

Question 8

examples of quantitative traits

Answer 8

height, weight, blood pressure, intelligence

Question 9

trait is either present or absent

Answer 9

threshold

Question 10

liability follows a bell-shaped distribution, and those individuals exceeding the threshold on the liability scale will express the trait

Answer 10

threshold

Question 11

examples of threshold traits

Answer 11

club foot, diabetes, cleft lip and palate, pyloric stenosis

Question 12

total genetic and environmental factors that contribute to development of a trait

Answer 12

liability

Question 13

amount of liability required to exhibit the trait

Answer 13

threshold

Question 14

true or false: liability may be different for males and females

Answer 14

true

Question 15

m?f for cleft lip and palate

Answer 15

m>f

Question 16

m?f for congenital hip dysplasia

Answer 16

f>m

Question 17

m?f for pyloric stenosis

Answer 17

m>f

Question 18

m?f for autism

Answer 18

m>f

Question 19

signs of multifactorial inheritance (4)

Answer 19

(1) familial concentration of a disease or trait without a clear mendelian pattern of inheritance
(2) absence of clear biochemical defects resulting from a single abnormal gene
(3) considerable variation in severity and expression of the phenotype
(4) gender difference in the frequency of occurrence

Question 20

____ ____ are less clear in multifactorial traits than for those that follow mendelian inheritance

Answer 20

recurrence risks

Question 21

_____ is obtained by observation in family or population studies

Answer 21

data

Question 22

5 recurrence risk rules

Answer 22

1. the greater the severity of the proband, the greater the recurrence risk
2. recurrence risk is greater if the proband is of the less commonly affected sex
3. recurrence risk is higher if more than one family is affected
4. recurrence risk decreases rapidly in more distantly related individuals
5. recurrence risk for first degree relatives is approx. the square root of the population incidence of the trait

Question 23

true or false:

the lesser the severity, the higher the recurrence risk

Answer 23

false–> higher severity, higher risk

Question 24

is the trait due to genes, environment, or both?

Answer 24

estimate heritability

Question 25

can we locate the causal genes for this trait?

Answer 25

perform linkage analysis 'family studies'

Question 26

can we identify the specific risk alleles for this trait?

Answer 26

perform association studies " population-based studies"

Question 27

measure of the proportion of the total phenotypic variance of a trait in a population that is due to genetics

Answer 27

heritability

Question 28

the value of heritability is always a fraction between ___ and ___

Answer 28

between 0 and 1

Question 29

h2 of 1= entirely genetic --> phenotypic variance=

Answer 29

genetic variance

Question 30

estimated from the incidence of a trait among relatives of a known degree of relatdness

Answer 30

heritability

Question 31

twin studies, observations of familial aggregation

Answer 31

heritability

Question 32

heritability of a trait is estimated from concordance rates for monozygotic versus dizygotic twins

Answer 32

twin studies

Question 33

Monozygotic twins share ____% of their genetic information while dizygotic twins share ___% of their genetic information

Answer 33

100% MZ | 50% DZ

Question 34

true or false: if DZ twins share a trait more often than MZ twins, then this suggests that the trait is influenced by genetic factors

Answer 34

false, if DZ share a trait more than it is influenced y genetics

Question 35

used to determine whether the inheritance of a genetic marker is associated with a particular disease/ trait in a family

Answer 35

linkage analysis

Question 36

goal for linkage analysis

Answer 36

to identify a region of the genome which cosegregates with the disease

Question 37

historically, it was used to identify genetic regions where a ____ _____ gene could be found

Answer 37

candidate disease

Question 38

most effective for regions with a _____ ____. Less effective in locating regions which play a role in _____ _____

Answer 38

large effect and less effective in multifactorial traits

Question 39

two genetic markers are located close enough together on a chromosome to be inherited together. a recombination is even is unlikely to occur between them

Answer 39

linkage

Question 40

a statistical measure of how likely it is for two genetic marker to be linked. based on recombination frequency

Answer 40

LOD score

Question 41

LOD>3

Answer 41

statistically significant evidence of linkage

Question 42

LOD

Answer 42

statistically significant evidence against linkage

Question 43

goal of association studies

Answer 43

to identify marker alleles for a particular disease/trait within an already designated region or across the genome

Question 44

based on the hypothesis that a particular allele occurs more frequently in individuals with the disease than in controls

Answer 44

association studies s

Question 45

uses SNPs

Answer 45

association studies

Question 46

___ ___ ___ changes in the DNA which occur throughout the genome

Answer 46

single base pair

Question 47

association studies can identify genes with a ___ ____ ___ which may play a role multi factorial disease

Answer 47

small overall effect

Question 48

(2) limitations of association studies

Answer 48

(1) association of a SNP allele with a phenotype does not prove that once causes the other(correlation does not equal causation) (2) a larger number of markers are needed because the marker allele needs to be closely linked to the disease locus

Question 49

GWAS

Answer 49

genome wide association studies

Question 50

variant with ____ frequency in cases than controls in GWAS

Answer 50

higher

Question 51

true or false: risk of developing Alzheimer's disease doubles in individuals with an affected first degree relative

Answer 51

Alzheimer's disease

Question 52

which apolipoprotein has been studied extensively as a risk factor in Alzheimer's disease

Answer 52

APOE

Question 53

follows a bell-shaped curve in the general population

Answer 53

liability

Question 54

fragile x syndrome follows which type of inheritance?

Answer 54

non-mendelian

Question 55

Cleft palate follows which type of inheritance

Answer 55

threshold

Question 56

marfan follows which type of inheritance?

Answer 56

mendelian

Question 57

height follows which type of inheritance?

Answer 57

quantitative

Question 58

who has higher liability for a condition that is more common in males and has the condition? - female - male

Answer 58

female

Question 59

multifactorials traits > or < 100% concordance of monozygotic twin

Answer 59

less than

Question 60

dizygotic concordance is > or < than monozygotic concordance

Answer 60

less than

Question 61

limitations with GWAS

Answer 61

reproducibility

Question 62

population based study

Answer 62

GWAS

Question 63

Family based study

Answer 63

Linkage analysis

Question 64

In general, the recurrence risk for most isolated birth defects is approximately ____

Answer 64

4%

Question 65

Concordance rate = (formula_

Answer 65

Concordance rate= # of all concordant pairs / # of all twin pairs

Question 66

Heritability (h^2) = (formula)

Answer 66

H^2= (MZ concordance - DZ concordance) x 2

Question 67

If a trait has 100% genetic concordance MZ=_ and DZ=+,

Answer 67

MZ=1 and DZ=0.5