Multifactorial and Polygenic Inheritance

Question 1

How can you tell if something is multifactorial?

Answer 1

not 100% in monozygotic twins

Question 2

What is polygenic?

Answer 2

genetic load determines risk (i.e more than one gene)

Question 3

Diabetes type I and II, cleft lip, pyloric stenosis, NTD are all what?

Answer 3

polygenic/multifactorial

Question 4

HOw can you prevent complications from diabetes?

Answer 4

blood glucose and lipid levels are kept in check

Question 5

Why has diabetes increased?

Answer 5

environmental factors/ obesity

Question 6

Is susceptibility to obesity and diabetes genetic?

Answer 6

yes

Question 7

HOw can you know that obesity and diabetes has genetic linkage?

Answer 7

cuz mono and dizygotic twins dont have the same ratio of obesity.

Question 8

If the concordance rate for both monozygotic and dizygotic twins is 40x higher than
the population risk, is the risk of disease predominantly genetic or environmental?

Answer 8

environmental, cuz if mono and di have the same concordance rate, then it is influenced by environment completely

Question 9

How do you get calculate the heritability caused by genes?

Answer 9

Heritability (concordance rate)= (monozygotic twins–dizogotic) X 2.

Question 10

In what type of diabetes do you have normal glycemic control and then it messes up?

Answer 10

type I

Question 11

In polygenic/multifactorial disorders, although clearly genetic, risk cannot be calculated based on (blank)

Answer 11

degree of relationship i.e. probability of shared genes

Question 12

In polygenic/multifactorial disorders, how are recurrence risks determined?

Answer 12

empirical data

Question 13

In polygenic/multifactorial disorders, recurrence risk will change from population to population and from family to family due to differences in (blank)

Answer 13

genetic load

Question 14

When dealing with polygenic/multifactorial inheritence, how can you know that this is what is occuring just by looking at recurrence risk?

Answer 14

because the relationship between distant family members (coefficient of relationship) with an affected indivdiual doesnt correlated correctly. In fact, risk is less than predicted

Question 15

(blank) increases if more than one family member affected.

Answer 15

recurrence

Question 16

Recurrence risk is higher if proband is of the less commonly affected (blank)

Answer 16

sex

Question 17

In multifactorial/polygenic inheritance, if you are affected, what is the liklihood that your aunt is affected?

Answer 17

significantly lower than the coefficient of relationship would suggest. Like 7% or something

Question 18

(blank) trait is when the phenotype distributes across a more or less
Gaussian (normal) distribution across a population.

Answer 18

quantitative trait

Question 19

What does this describe:
disease does not have a normal distribution, but is the result of a continuous underlying liability. If threshold is exceeded, then disease results.

Answer 19

threshold of liability

Question 20

In threshold liability, the disease doesnt have a normal (blank). HOwever, the genetic susceptibility does.

Answer 20

gaussian distribution

Question 21

(blank) can alter thresholds.

Answer 21

sex

Question 22

If you have a multifactorial/polygenic disease that must reach a threshold and it is seen more often in males, who would be at greater risk siblings of an affected female or of an affected male?

Answer 22

female