Multifactorial Diseases

Question 1

What does the threshold of liability indicate/?

Answer 1

how many contributing alleles are required for a patient to be affected by a disease

Question 2

What is a concordant trait?

Answer 2

a trait shared by both twins

Question 3

What is a discordant trait?

Answer 3

a trait not shared by twins

Question 4

What does high heritability indicate?

Answer 4

that a disease is mainly determined by genetic factors

Question 5

What is incidence?

Answer 5

describes how many new cases are recorded in a given time

Question 6

What is prevalence?

Answer 6

describes the proportion of the population that is affected by the disease at any given time

Question 7

What are the most common genetic diseases?

Answer 7

multifactorial inheritance

Question 8

How can one estimate the number of genes involved in a multifactorial disease?

Answer 8

shape of bell curve

Question 9

Regarding a multifactorial disease, the higher number of genes involved does what to the shape of the bell curve?

Answer 9

lower the fraction of extreme phenotypes

Question 10

What is a liability distribution?

Answer 10

shape of bell curve of phenotypes for multifactorial diseases

Question 11

Why does the recurrence risk of a multifactorial disease increase with each diagnosis of a relative?

Answer 11

more disease contributing alleles likely present

Question 12

Which sex is more likely affected by pyloric stenosis?

Answer 12

male

Question 13

Which sex requires fewer contributing alleles to develop pyloric stenosis?

Answer 13

males

Question 14

If a female develops pyloric stenosis, what does this mean for the number of contributing alleles she possesses?

Answer 14

she likely has a larger number

Question 15

What is a concordant trait?

Answer 15

a trait shared by two twins

Question 16

What is the term for a trait not shared by twins?

Answer 16

discordant

Question 17

What is the equation for heritability?

Answer 17

(concordance MZ - concordance DZ)*2

Question 18

What is incidence?

Answer 18

how many new cases are recorded in a given time divided by the size of the population

Question 19

What is prevalence?

Answer 19

proportion of population that is affected at any given time

Question 20

What is the equation for relative risk ratio?

Answer 20

prevalence of disease of relatives / prevalence of the disease in the general population

Question 21

Do multifactorial diseases follow Mendelian inheritance?

Answer 21

No

Question 22

Do multifactorial diseases show complete or incomplete penetrance?

Answer 22

incomplete

Question 23

On what chrmosome is the MHC gene found?

Answer 23

chromosome 6

Question 24

What are MHC class I and II genes involved in?

Answer 24

initiating immune response

Question 25

How are HLA genes transmitted? Why is this?

Answer 25

as a whole unit very little meiotic recombination

Question 26

What is a compound heterozygote?

Answer 26

two mutant alleles are not identical

Question 27

What is the genetic transmission of the HLA genes classified as?

Answer 27

haplotype

Question 28

How are the HLA haplotypes expressed?

Answer 28

co-dominant

Question 29

What is the percentage of MHC haplotypes shared by parent and child?

Answer 29

half

Question 30

What are the changes of two siblings sharing identical haplotypes?

Answer 30

25%

Question 31

In order to find an organ donor, what must one do?

Answer 31

match the HLA haplotypes

Question 32

What haplotype affects T1D?

Answer 32

DR-DQ

Question 33

What is HLA-B associated with?

Answer 33

Spondyloarthropathy

Question 34

What is HLA-C associated with?

Answer 34

Psoriatic Arthritis