Blood Groups Flashcards
What are ABO blood groups dependant on
Antigens on the RBC which are present depending on the alleles inherited
What can the RBC antigens for blood group be made of
Glyclolipids
Glycoproteins
Antigen alleles are inherited from each parent, when can these antigens change
With diseases like cancer
Which 3 enzymes are involved in ABO blood groups
Fucosyl transferase (FUT1)
N acetyl galactosamine (A transferase)
Glucosamine transferase (B transferase)
What is the overall name given to A transferase or B transferase and their job
Glycosyltransferase
Add sugars to the terminal end on glycolipids or proteins
Name 5 sugars present in the ABO blood groups
Fucose
N acetyl galactosamine
Glucosamine
Sialic acid (NANA) - on gangliosides
Which 2 genes determine blood group
ABO and H gene
What does HH or Hh encode for
Fucosyl transferase FUT1
Adds a fucose to the rbc precursor sequence
What is a precursor substance
Oligosaccharides already present on the RBC
What happens when someone has recessive hh gene
No FUT1 produced
No fucose added
No A or B transferase addition of sugars
What is H substance/ antigen known as because of no A or B antigens
O antigen
Why do A and B genes differ
Deletions at exon 6 out of 7
Causes amino acid differences
Encode for different transferases
What is added when someone has AA or AO alleles
N acetyl galactosamine
Via A transferase
What is added when someone inherits BO or BB alleles
Glucosamine
By B transferase
What happens when someone has AB alleles
Codominant
Causes some antigens to be A with n acetyl galactosamine
Some antigens have only glucosamine
What is the difference between A1 and A2 phenotype
A1- antigens which react with anti A1 antibodies
A2- don’t react with anti A1 antibodies
What genotypes would parents need to be to form all 4 possible blood groups
AO and BO
What type of antibodies are formed by the 4 blood types when exposed to the blood group
A = anti B antibodies
B= anti A antibodies
AB= no antibodies
O= both antibodies (because no A or B antigens present)
What occurs when mismatches transfusion occurs
Agglutination when the antibodies detect the antigen in the RBC of donor
They will cause clumping of RBC and lyse
Why can incompatible transfusion cause kidney disease
Because more erythropoietin needs to be produced over and over to restore RBC that have been lysed
What are rhesus antigens made of
Protein
Which antigen for rhesus is most common
Rhesus D
What happens when someone is DD or Dd for the rhesus antigen
They produce the rhesus antigen and are RH+
Why aren’t anti RH antibodies not commonly produced
Because RH + blood group isn’t common
People need exposure of Rh to have antibodies for it
What does anti RH antibody do
RBC get bound to the IgG and are engulfed by macrophages
The liver and spleen then remove the RBC
Which blood group is a universal donor and why
O-
It has no A , B or Rh antigens on rbc surface
Why can’t O- recieve blood from anyone not O-
It has A B and Rh antibodies on surface
Why is AB+ a universal recipient
It hasn’t got A,B or Rh antibodies at all
Why can AB only donate to AB
Because they have both A and B antigens
Why can rhesus cause disease in pregnancy
If rhesus + dad, baby will have Rh antigens in side a Rh- woman
If the Rh antigens from baby transfer to woman she can produce anti RH
If next baby is RH+ the anti RH in mother attacks rbc of baby= anemia due to engulfment by macrophages
Which class of antibody can’t cross placenta if mother and child are diff blood groups
IgM
Name 3 other blood group antigens Other than rhesus and ABO
Lewis
P family
Forssman antigens
