Mhc And Disease And Maintaing Dicersity

Question 1

Why do we need to balance diversity but not too much diversity of MHC

Answer 1

Too much would cause autoimmunity

Question 2

Does MHC variants only increase risk of disease

Answer 2

No can be protective

Question 3

Which allele associated with ankylosing spondylitis

Answer 3

Hla b27

Question 4

What is ankylosing spondylitis

Answer 4

Chronic inflammation affecting flexibility of vertebra

Question 5

Which other mutated peptide which is linked to b27 allele effects have combined highest AS risk

Answer 5

Erap1

Question 6

What is b27 protective in

Answer 6

Hiv progression

Question 7

Which subtype of b35 causes faster aids progression from hiv

Answer 7

Py(3503,02,04)

Question 8

Why is py different to px subtypes which have no effect on progression

Answer 8

Py at position 9 cannot bind peptides with tyrosine residues. Px can and therefore can bind to hiv peptides and present.

Py can’t

Question 9

Which position are Px and py alleles the same

Answer 9

Position 2 proline

Question 10

Which disease is linked to the dr-Dq haplotype

Answer 10

Type 1 diabetes
Autoimmunity presenting pancreatic b cells

Question 11

Having aspartic acid at position 57 on hladq beta is protective. How

Answer 11

It is negative cooh which interacts with the arginine at p76 on alpha chain. This causes ionic bond = stability

Question 12

Why are positive aa like alanine at 57 not stable causing autoimmunity

Answer 12

Can’t form ionic bond with arginine76

Question 13

Which other disease autoimmune linked to the dqb chain and aspartate 57 position

Answer 13

Coeliac disease

Question 14

Why does the py genotype not determine you’ll get hiv progression

Answer 14

Depends on other genetic and environment factors

Question 15

What combination of hla was found best to stop severe illness in covid

Answer 15

Heterozygosity and having alleles which present more peptides

Question 16

Which types of drugs do MHC usually cause adverse reactions with

Answer 16

Anti cancer or antimicrobial

Question 17

Give example of hypersensitivity sue to hla allele

Answer 17

Abacavir and b57

Question 18

How does the drug cause hypersensitivity ie self ag is being attacked by T cells

Answer 18

The drug changes the aa preferences of the hla molecule and now it can present potential self ag and cause a T cell response

Question 19

What is the theory of parasite mediated MHC evolution

Answer 19

MHC will be introduced into the world with low frequency. With better fitness

As soon as it is acquired by more people the parasite will mutate and this myc allele no longer fit.

Ie fitness is negatively proportional to frequency of allele

Example is ebv and hla 11

Question 20

What is the sexual selection theory of MHC diversity maintenance

Answer 20

Females will find men with dissimilar MHC more attractive = keeping heterozygosity

Question 21

How was this tested and what factor affects this

Answer 21

Sniff test

Hormone changes eg pregnancy or oral contraception found to prefer similar MHC males

Question 22

Why is not choosing dissimilar partners an issue

Answer 22

Can cause spontaneous abortions and reduced fertility, harder to get pregnant on ivf etc

Also worse infections