ABO, H and Secretions Flashcards
Which chromosome are ABO located on?
Chromosome 9
What do glycosyltransferases do?
An enzyme that catalyzes transfer of glycosyl groups in biochem reactions
Which chromosome are H and Se located on?
Chromosome 19
Describe H gene
- FUT1
- Transfers L-fucose (precursor substance on RBC membrane)
- acts on type 2 chains
What is the main glycosyltransferase acting on the chains?
α-2-L fucosyltransferase
Describe Se gene
- FUT2
- acts on type 1 chains
- forms H substance in secretions “soluble antigens”
What are the type 1 and type 2 chains?
Type 1 - β 1-3
Type 2 - β 1-4
What is the purpose of FUT2?
Directly responsible for regulating secretor genes
Which glycosyltransferase and immuno-dominant sugar is present with H?
- α-2-L- fucosyltransferase
- L-fucose
Which glycosyltransferase and immuno-dominant sugar is present with A?
- α-3-N-acetylgalactosaminyl
transferase - N-acetyl-D-galactosamine
Which glycosyltransferase and immuno-dominant sugar is present with B?
- α-3-D-galactosyltransferase
- D-galactose
What is “Bombay”?
Has geneotype hh, therefore can’t determine their ABO group without pedigree chart
What are the A subgroups? Which one is more common?
A1 (80%) and A2 (20%)
What commercial reagent (antisera) detects A1?
Dolichus Bifloris (lectin anti-A1)
Who discovered the ABO system?
Karl Landsteiner et al
Neonates (<4mo) only have which ABO test? And why?
Only have a forward test, no reverse.
Because of delayed production of antibodies.
ABO are primarily which antibody?
IgM
Describe forward testing.
- Tests for antigens on red cell
- Antigens are unknown, by using known antibodies to visualize reaction.
Describe reverse testing.
- Tests for antibodies in plasma/serum
- Antibodies are unknown, use commercial groups A, B and AB
What commercial reagent (antisera) detects H? Why is this necessary?
Ulex Europeaus (Lectin- anti-H) Helpful in troubleshooting a Bombay phenotype.
What is different about testing for secretions?
- It is an neutralization test, meaning it is the opposite to ABO grouping.
- A reaction indicates that the antibody is NOT present.
