The ABO Blood Group System
H gene
-(H and h) located on chromosome 19 -produces the transferase l-fucosyltransferase and changes it to l-fucose to end of type II chain -final blood group 0
bombay phenotype
-Oh (blood group o) -do not inherit the h gene -they cannot make the h transferase needed to convert type 2 precursor chain to type 2 h chain -they make anti-h
O gene
-blood group o -amorph: no product expressed -h antigen remains unchanged
A and B genes
-located on chromosome 9 -produces transferase specific to a/b antigen (makes both)
A1
-most common subgroup -80% of ppl
A gene
-production of acetylgalactosaminyltransferase into acetyl-d-galactosamine to end of type II chain -final blood type A
B gene
-production of d-galactosyltransferase into d-galactose to end of type II chain -final blood type B
when do antibodies start to form..?
4-6 months after birth peak @ 5-10yrs
abo reagent colors (anti-a/-b/-A1
ANTI-A: BLUE ANTI-B:YELLOW ANTI-A1/H: COLORLESS, USED TO SOLVE ABO DISCREPANCIES.
what ig is associated whith the abo antibodies
IgM: Activate complement and react @rt or colder
major antigens of the abo system
a/b/h
the first blood group discovered
abo blood system
gene o
amorph gene (doesnt cause production)
o individuals contain what antibodies
anti-a/-b/-ab
major antibodies of abo system
anti-a/-b/-ab/-h
group 1 discrep.
antibodies -forward/reverse discrep due to weakly reacting/missing antibodies
group 2 discrep.
antigen-unexpected reactions in forward grouping due to weakly reacting/missing antigen
what chromosomes are abo blood group located
chromosome 9
what is the most common/rarest blood type
common: o and a rarest: ab
differentiation of subgroups
determined by using the reagent known as anti-a1 lectin (made from dolichos biflorus) lectin:agglut. the human cells (a1 cells not a2)
glycosyltransferase
enzyme that transfers carbohydrate (sugar) molecules onto a precursor molecule
abo discrepancies
forward/reverse do not match -discrep. must be resolved before transfusion -results recorded but not interp.
landsteiners rule
if abo antigen present=corresponding antibody will be present and visa-versa group A groupB groupAB groupO A B AB O anti-B anti-A none anti-A/-B A-antigen B-antigen A/B antigen none
most serious transfusion reactions are due to what...?
incompatibility involving the abo blood system
forward grouping
indiv. abo antigen using antisera -no agglut: neg./antigen absent -agglut: postivite/ antigen present
abo grouping
inverse reciprocal relationship between forward and reverse they check each other
abo system discovered by...?
karl landsteiner
group 4 discrep.
miscellaneous discrepancy- due to forward and reverse groupign s due to misc. probs
reverse grouping
presence/absence of individuals abo antibodies using rbc 2-4% cell suspension
group 3 discrep.
protiens-between forward/reverse groupings caused by protiens/plasma abnormalities -abnorm=rouleaux formation
what do the genes do for abo system
they code for the production of a specific glycosyltransferase
abo blood system is most significant when it comes to what..?
transfusions
two types of chains? which one has to do with the abo system?
type I chain:body fluids and secretions type II chain:(precursor substance on rbc) chain attatched through the rbc membrane onto ceramide protiens
