PSC1002/L04 Blood Groups

Question 1

Describe the work of Karl Landsteiner (1901). (3)

Answer 1

The ABO blood group system
Identified 3 blood types A, B, C
AB discovered 1 year later

Question 2

Define a blood group.

Answer 2

Classification of blood based on presence (or absence) of inherited antigenic substances on surface of RBCs

Question 3

Describe antigens of RBCs. (2)

Answer 3

Complex mixture of proteins, glycoproteins and glycolipids
Found on surface of all RBCs and range of other cells in body

Question 4

How many human blood groups systems/antigens are known?

Answer 4

43
>600 blood group antigens

Question 5

What is the +/- of a blood group?

Answer 5

Presence or absence of Rhesus D antigen

Question 6

What 5 sugars make up RBC antigens?

Answer 6

Fucose
Galactose
N-acetylgalactosamine
N-acetylglucosamine
Sialic acid

Question 7

Which enzymes are involved in blood groups? (3)

Answer 7

Fucosyl transferase (FUT1)
N-acetylgalactosamine transferase (A transferase)
Galactose transferase (B transferase)

Question 8

Which 2 genes are involved in blood group?

Answer 8

ABO
H

Question 9

What kind of enzyme do ABO and H genes encode?

Answer 9

Glycotransferases

Question 10

Name the alleles found at the ABO and H loci.

Answer 10

A, B, O
H or h

Question 11

What protein does the O (recessive) allele encode?

Answer 11

Truncated, non-functional protein

Question 12

What enzyme does the dominant H allele encode?

Answer 12

Fucosyl transferase

Question 13

Where is the H gene located?

Answer 13

Chromosome 19

Question 14

What is the ‘Bombay’ phenotype?

Answer 14

hh genotype
No symptoms or related disease
Can only receive transfusions from the same blood group

Question 15

Where is the ABO gene located? How many exons does it have?

Answer 15

Chromosome 9
7 exons

Question 16

What is the difference between the A, B and O alleles?

Answer 16

A&B differ by 7 nucleotide substitution - 4 different aa
Residues at 266&268 determine AB specificity
O: deletion in exon 6 - frameshift

Question 17

What is needed to catalyse the reaction of A&B transferase?

Answer 17

UDP

Question 18

What disease susceptibility is linked to ABO phenotype? (2)

Answer 18

Gastric cancer in group A
Gastric and duodenal ulcers in group O

Question 19

What effect does blood group have on factor VIII and vWF?

Answer 19

Group O have 25% less factor VIII and vWF in plasma

Question 20

What are blood group antigens/corresponding antibodies known as?

Answer 20

Agglutinogens
Agglutinins

Question 21

Describe haemolytic transfusion reaction. (3)

Answer 21

Donated RBC lyse in blood vessels
Complement system is activated
Leads to kidney failure, uncontrolled clotting , circulatory shock

Question 22

Describe how anti-Rh(D) antibodies destroy Rh(D)+ RBCs. (3)

Answer 22

RBC bound by IgG
Engulfed by macrophages
Transported to liver and spleen for removal

Question 23

What is the universal donor and recipient blood type?

Answer 23

Donor: O-
Acceptor: AB+

Question 24

What must be considered when finding a blood match? (2)

Answer 24

Donors antigens
Recipient’s antibodies

Question 25

When can new born haemolytic disease occur? (3)

Answer 25

Rh+ father and Rh- mother
Rh+ blood from foetus enters mother’s blood during delivery; mother produces anti-Rh antibodies
If pregnant again with Rh+, antibodies damage foetal RBC

Question 26

What class of antibodies are mother ABO antigens?

Answer 26

IgM