Multifactorial diseases

Question 1

define medelian

Answer 1

obeys Mendel’s laws of segregation – dominant, recessive, X-linked.-single gene

Question 2

define complex

Answer 2

inherited but non-Mendelian component

Question 3

define polygenic

Answer 3

the result of the action of multiple genes.

Question 4

define multifactorial

Answer 4

the result of multiple factors, usually including both genetic and environmental factors.

Question 5

what equation is used to determine the relative risk of second sibling

Answer 5

relative risk of the sibling/ relative risk of the general population.

Question 6

doe multifactorial diseases have a genetic component.

Answer 6

Yes
1- relative risk of second sibling
2-Twin studies- genetic characters should have a higher concordance (risk) in monozygotic twins compared to dizygotic twins because they have the same genes and similar environment

Question 7

what are the major problems in twin studies to look for genetic components affecting multifactorial conditions.

Answer 7

Monozygotic twins

• Assumption that the degree of environmental sharing is the same for MZ twins- can have different prenatal environments.
• diamniotic monozygotics.

Dyzygotic twins
-1 in 10 has undergone a blood transfusion from their dizygotic pair during pregnancy.

Question 8

what do adoptive studies show

Answer 8

show how much difference the environment can make on multifactorial conditions (have the same environment at their adoptive parents, however not the same genotype)

Question 9

Do gene involvement in multifactorial conditions have a additive effect

Answer 9

Yes.

more genes involved the more higher the risk is.

Question 10

what shaped curve does the normal distribution of common diseases form

Answer 10

Gaussian curve.

Question 11

what congenital malformations show multifactorial inheritance.

Answer 11

cleft lip/palate, congenital hip dislocation, congenital heart defects, neural tube defects, pyloric stenosis, talipes

Question 12

what acquired diseases of childhood and adult hood show multifactorial inheritance

Answer 12

asthma, autism, cancer, diabetes mellitus, epilepsy, glaucoma, hypertension, inflammatory bowel disease (Crohn disease), ischaemic heart disease & stroke, bipolar disorder, multiple sclerosis, Parkinson disease, psoriasis, rheumatoid arthritis, schizophrenia

Question 13

What does a association study show.

Answer 13

relate variation in human DNA sequence with a disease or trait

Question 14

What markers are commonly tested in association studies

Answer 14

SNP’s

Question 15

what does a higher number of SNP’s in a person mean

Answer 15

They are more likely to have a disease of trait.

Question 16

what does the mapping of medelian conditions reveal.

Answer 16

Medelian-rare but have severe effect (in terms of symptoms)

Question 17

what does the mapping of multifactorial conditions reveal.

Answer 17

frequent in both control and case but more common in patients (E.g. SNP)

Question 18

what does SNP stand for

Answer 18

single nucleotide polymorphism

Question 19

what effect do SNP’s have on diseases

Answer 19

They are usually present but create not effect on phenotype. Rarely they can cause a disease trait.
Common usually binary (relating to or associated with)

Question 20

How are SNP’s tested for

Answer 20

SNP’s hybridised to oligonucleotide probes on a glass film.

The probe will show whether you have both the same bases on the 2 chromosomes or 2 different.

Question 21

How are SNP’s inherited and how are the linked to increasing the risk of causing disease.

Answer 21

SNP’ are inherited in the DNA which surrounds the mutation.
SNP’s are not the cause of the mutation, however they are passed on alongside the mutation due to their proximity.
Over generations the increased frequency of SNP’s can result in reaching a significance level at which the SNP increases the relative suceptibitiy of each disease.

Question 22

What method/ tool is used to determine medelian inheritance

Answer 22

family tree.

Question 23

In Alzheimer’s disease you do not inherit the condition what do you inherit

Answer 23

susceptibility

Question 24

what are some of the main genes which predispose you to developing Alzheimer’s

Answer 24

Preseniln 1, presenilin -encode new transmembrane aspartyl proteases with g-secreatase activity responsible for proteolytics cleavage of amyloid beta A4 precursor protein (APP)

Question 25

what apolipoprotein in involved in protecting and increasing risk of developing Alzheimer’s.

Answer 25

apolipoproetien E.

Question 26

which haplotype of apolipoprotein confers increased susceptibility to alziehmers.

Answer 26

E4 haplotype 
(arg and arg)

Question 27

which haplotype of apolipoprotein confers protective effect to alziehmers.

Answer 27

E2 haplotype 
(cys and cys)

Question 28

Is alzihemers affected by the environment

Answer 28

Yes

more you use your brain onset of alzeihimers is delayed.

Question 29

what multifactorial condition does the early deposition of drusen in the eye lead to

Answer 29

age- related macular degeneration

Question 30

what environment al risk factor increases the risk of developing age related macular degeneration

Answer 30

smoking - main

light exposure

Question 31

what genes increase the susceptibility of developing age related macular degeneration

Answer 31

CFH (1q), ARMS2 (10q)