Mhc And Disease And Maintaing Dicersity Flashcards
Why do we need to balance diversity but not too much diversity of MHC
Too much would cause autoimmunity
Does MHC variants only increase risk of disease
No can be protective
Which allele associated with ankylosing spondylitis
Hla b27
What is ankylosing spondylitis
Chronic inflammation affecting flexibility of vertebra
Which other mutated peptide which is linked to b27 allele effects have combined highest AS risk
Erap1
What is b27 protective in
Hiv progression
Which subtype of b35 causes faster aids progression from hiv
Py(3503,02,04)
Why is py different to px subtypes which have no effect on progression
Py at position 9 cannot bind peptides with tyrosine residues. Px can and therefore can bind to hiv peptides and present.
Py can’t
Which position are Px and py alleles the same
Position 2 proline
Which disease is linked to the dr-Dq haplotype
Type 1 diabetes
Autoimmunity presenting pancreatic b cells
Having aspartic acid at position 57 on hladq beta is protective. How
It is negative cooh which interacts with the arginine at p76 on alpha chain. This causes ionic bond = stability
Why are positive aa like alanine at 57 not stable causing autoimmunity
Can’t form ionic bond with arginine76
Which other disease autoimmune linked to the dqb chain and aspartate 57 position
Coeliac disease
Why does the py genotype not determine you’ll get hiv progression
Depends on other genetic and environment factors
What combination of hla was found best to stop severe illness in covid
Heterozygosity and having alleles which present more peptides
Which types of drugs do MHC usually cause adverse reactions with
Anti cancer or antimicrobial
Give example of hypersensitivity sue to hla allele
Abacavir and b57
How does the drug cause hypersensitivity ie self ag is being attacked by T cells
The drug changes the aa preferences of the hla molecule and now it can present potential self ag and cause a T cell response
What is the theory of parasite mediated MHC evolution
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
What is the sexual selection theory of MHC diversity maintenance
Females will find men with dissimilar MHC more attractive = keeping heterozygosity
How was this tested and what factor affects this
Sniff test
Hormone changes eg pregnancy or oral contraception found to prefer similar MHC males
Why is not choosing dissimilar partners an issue
Can cause spontaneous abortions and reduced fertility, harder to get pregnant on ivf etc
Also worse infections
