ABO, H and Secretions

Question 1

Which chromosome are ABO located on?

Answer 1

Chromosome 9

Question 2

What do glycosyltransferases do?

Answer 2

An enzyme that catalyzes transfer of glycosyl groups in biochem reactions

Question 3

Which chromosome are H and Se located on?

Answer 3

Chromosome 19

Question 4

Describe H gene

Answer 4

• FUT1
• Transfers L-fucose (precursor substance on RBC membrane)
• acts on type 2 chains

Question 5

What is the main glycosyltransferase acting on the chains?

Answer 5

α-2-L fucosyltransferase

Question 6

Describe Se gene

Answer 6

• FUT2
• acts on type 1 chains
• forms H substance in secretions “soluble antigens”

Question 7

What are the type 1 and type 2 chains?

Answer 7

Type 1 - β 1-3

Type 2 - β 1-4

Question 8

What is the purpose of FUT2?

Answer 8

Directly responsible for regulating secretor genes

Question 9

Which glycosyltransferase and immuno-dominant sugar is present with H?

Answer 9

• α-2-L- fucosyltransferase

- L-fucose

Question 10

Which glycosyltransferase and immuno-dominant sugar is present with A?

Answer 10

• α-3-N-acetylgalactosaminyl
  transferase
• N-acetyl-D-galactosamine

Question 11

Which glycosyltransferase and immuno-dominant sugar is present with B?

Answer 11

• α-3-D-galactosyltransferase

- D-galactose

Question 12

What is “Bombay”?

Answer 12

Has geneotype hh, therefore can’t determine their ABO group without pedigree chart

Question 13

What are the A subgroups? Which one is more common?

Answer 13

A1 (80%) and A2 (20%)

Question 14

What commercial reagent (antisera) detects A1?

Answer 14

Dolichus Bifloris (lectin anti-A1)

Question 15

Who discovered the ABO system?

Answer 15

Karl Landsteiner et al

Question 16

Neonates (<4mo) only have which ABO test? And why?

Answer 16

Only have a forward test, no reverse.

Because of delayed production of antibodies.

Question 17

ABO are primarily which antibody?

Answer 17

IgM

Question 18

Describe forward testing.

Answer 18

• Tests for antigens on red cell

- Antigens are unknown, by using known antibodies to visualize reaction.

Question 19

Describe reverse testing.

Answer 19

• Tests for antibodies in plasma/serum

- Antibodies are unknown, use commercial groups A, B and AB

Question 20

What commercial reagent (antisera) detects H? Why is this necessary?

Answer 20

Ulex Europeaus (Lectin- anti-H)
Helpful in troubleshooting a Bombay phenotype.

Question 21

What is different about testing for secretions?

Answer 21

• It is an neutralization test, meaning it is the opposite to ABO grouping.
• A reaction indicates that the antibody is NOT present.