-
What 2 genes are responsible for the MNSs System & where is it located?
Located on Chromosome 4
- 1st gene is: GYPA - this produces Glycophorin A (GPA).
- 2nd gene is: GYPB - This produces Glycophorin B (GPB).
-
What protein structure produces the M and N antigens?
Glycophorin A
-
What protein structure produces the S and s antigens?
Glycophorin B
-
Remember: Terminology: 3 descriptions
Haplotype
Is a linked set of genes inherited together because of their close proximity on a chromosome.
A set of alleles from closeley linked genes
A term used in HLA testing to denote the five genes (HLA -A HLA -B, HLA-C, HLA-D,HLA-DR) on the same chromosome.
-
How do we inherit the MNSs system?
- From a haplotype
- aka:
- a set of alleles from closely linked genes
-
What does the MNSs haplotype include?
Both GYPA & GYPB gene
-
How are closely linked are M and N antigens?
They are very close. Only on position 1 & 5 on the chromosome do they differ.
-
If you inherited the M antigen (GPAM) what amino acid is produced at positions 1 & 5?
- 1: is Serine
- 5: is Glycine
-
If you inherited the N antigen (GPAN) what amino acid is produced at positions 1 & 5?
- 1: is Leucine
- 5: is Glutamic
-
If you inherited the S antigen (GPAS) what amino acid is produced at position 29 of the chromosome?
Methionine will be found
-
If you inherited the s antigen (GPAs) what amino acid is produced at position 29 of the chromosome?
Threonine will be present
-
What are the 4 possible haplotypes (closely linked alleles) for the MNSs system?
-
What does Linkage disequilirium mean?
This is when certain haplotypes are found more frequently than what we expected in the normal population.
-
What happens if sections of the GPA were deleted?
- Then the cells would be considered as
- En-negative
-
What happens if sections of the GPB were deleted?
- Cells would be describes as:
- U-negaitve (a heterozygous group)
-
U-negative RBC's always lack what antigen?
-
What would the null cell in this blood group sytem be?
MkNk (when genes 2-7 of GYPA and genes 1-5 GYPB are deleted)
These cells will not have MNSs, En or U antignes.
note: En & U are high incidence
-
List M & N antigen:
Significance, antibody class, optimal temp, reaction phase, enzyme treated RBC's enhanced or destroyed
Is notClinically significant
Naturally occuring
IgM
Agglutination is observed at both 37oC as well as at or below RT (room temp)
Reacts at: IS, 37C, & AHG
Enzyme treatment will destroy postivie agglutinations
-
List S and s antigen:
Significance, antibody class, optimal temp, reaction phase, enzyme effects on RBC's
Clinically Significant
IgG
Reacts best at 37oC
Reaction phases: IS, 37C, or AHG
Enzymes: ficin and papain inhibit agglutination. Typsin does not destroy reaction.
-
EN complex is very complicated...So, regarless of the type of EN Cells, if they lack EN...They also lack what other High Incidence antigen?
Wrb
-
Wrb is actually part of what blood group and at what location?
Diego BG System at band 3 protein.
-
How does Wrb and teh MNSs system interact?
The GPA and band 3 interact at a cellular level and when GPA is absent form the RBC's, this ineraction can't occur because these cells will not express Wrb.
-
When might inhance the reaction of Anti- M, N, S, or s?
Cells that are homozygous rather than heterozygous
|
|
