Unit 2.2 ABO Blood Group

Question 1

What is the immunodominant sugar responsible for H specificity?

Answer 1

L-fucose

Question 2

What phenotype lacks the normal expression of the ABH antigens due to the inheritance of the hh genotype?

Answer 2

Bombay phenotype

Question 3

What do you call individuals who inherit the sese genotype?

Answer 3

Non-secretors

Question 4

What is the source of the anti-A1 lectin?

Answer 4

Dolichos biflorus

Question 5

Which blood group has the highest amount of H antigen?

Answer 5

Blood group O

Question 6

Who first reported the Bombay phenotype, and when?

Answer 6

Bhende in 1952

Question 7

What gene mutation causes the Bombay phenotype?

Answer 7

Mutation in FUT1 (H gene) and FUT2 (Se gene)

Question 8

What type of inheritance does the Bombay phenotype follow?

Answer 8

Autosomal recessive

Question 9

Which antigen is found in the greatest concentration on the RBCs of group O individuals?

Answer 9

H antigen

Question 10

What is the percentage of A1 individuals among all A (or AB) blood group individuals?

Answer 10

0.8

Question 11

What percentage of A2 (or A2B) individuals produce anti-A1?

Answer 11

22% to 35%

Question 12

Which immunoglobulin class is anti-A1 typically classified as?

Answer 12

IgM

Question 13

What is the immunodominant sugar for the A antigen?

Answer 13

N-acetyl-D-galactosamine

Question 14

What is the immunodominant sugar for the B antigen?

Answer 14

D-galactose

Question 15

Which subgroup of A has more antigen sites on RBCs, A1 or A2?

Answer 15

A1

Question 16

How many antigen sites are typically found on adult A1 RBCs?

Answer 16

810,000 to 1,170,000

Question 17

How many antigen sites are typically found on adult A2 RBCs?

Answer 17

240,000 to 290,000

Question 18

What is the main function of lectins in blood typing?

Answer 18

Agglutinate specific blood group antigens

Question 19

Which lectin is used to identify the H antigen?

Answer 19

Ulex europaeus

Question 20

Which lectin is used to identify the A antigen?

Answer 20

Helix pomatia

Question 21

Which lectin is used to identify the A1 antigen?

Answer 21

Dolichos biflorus

Question 22

Which lectin is used to identify the B antigen?

Answer 22

Bandeiraea/Griffonia simplicifolia

Question 23

Which lectin is used to identify the M antigen?

Answer 23

Iberis amara

Question 24

Which lectin is used to identify the N antigen?

Answer 24

Molucella laevis, Bauhinia purpura

Question 25

Which lectin is used to identify the T antigen?

Answer 25

Arachis hypogaea (peanut lectin)

Question 26

Which lectin is used to identify the Tn antigen?

Answer 26

Salvia sclarea

Question 27

What type of blood should be given to a patient with the Bombay phenotype in case of transfusion?

Answer 27

Bombay blood type (Oh)

Question 28

What is the function of the FUT1 gene?

Answer 28

Encodes an enzyme that adds fucose to the precursor chain to form the H antigen

Question 29

What is the function of the FUT2 gene?

Answer 29

Determines if an individual is a secretor or non-secretor

Question 30

Which blood type has the least amount of H antigen?

Answer 30

A1B

Question 31

Why do A1 individuals have very little detectable H antigen?

Answer 31

Almost all H antigen is converted to A1 antigen

Question 32

What does anti-H differentiate between in blood typing?

Answer 32

Type O and Bombay phenotype

Question 33

What is a characteristic of the para-Bombay phenotype?

Answer 33

Has little to no H antigen on RBCs but may have some in secretions

Question 34

Which antibody is found in type O individuals?

Answer 34

Anti-A and Anti-B

Question 35

What is the primary cause of ABO discrepancies?

Answer 35

Mismatch between forward and reverse typing results

Question 36

What are common sources of technical errors in ABO typing?

Answer 36

Mislabeling, improper reagent use, incorrect cell suspension

Question 37

What blood type is considered the universal donor for RBC transfusions?

Answer 37

O negative

Question 38

What blood type is considered the universal recipient for RBC transfusions?

Answer 38

AB positive

Question 39

What type of antibody is typically present in group A individuals?

Answer 39

Anti-B

Question 40

What type of antibody is typically present in group B individuals?

Answer 40

Anti-A

Question 41

What type of antibody is present in group AB individuals?

Answer 41

None

Question 42

What type of antibody is present in group O individuals?

Answer 42

Anti-A and Anti-B

Question 43

What is the function of reverse typing in ABO testing?

Answer 43

Detects antibodies in the serum against RBC antigens

Question 44

What is the function of forward typing in ABO testing?

Answer 44

Detects antigens on RBCs using known antisera

Question 45

What is the main characteristic of Group I ABO discrepancies?

Answer 45

Weak or missing antibodies in reverse typing

Question 46

What are some causes of Group I ABO discrepancies?

Answer 46

Newborns, elderly, immunosuppression, hypogammaglobulinemia

Question 47

What is the main characteristic of Group II ABO discrepancies?

Answer 47

Weak or missing antigens in forward typing

Question 48

What are some causes of Group II ABO discrepancies?

Answer 48

Subgroups of A or B, leukemia, cancer, acquired B phenomenon

Question 49

What is the main characteristic of Group III ABO discrepancies?

Answer 49

Rouleaux formation or plasma protein abnormalities

Question 50

What conditions can cause Group III discrepancies?

Answer 50

Multiple myeloma, Waldenstrom’s macroglobulinemia, increased fibrinogen

Question 51

What is the main characteristic of Group IV ABO discrepancies?

Answer 51

Miscellaneous problems like cold autoantibodies or mixed-field reactions

Question 52

How is a Group III ABO discrepancy resolved?

Answer 52

Saline replacement technique

Question 53

What is mixed-field agglutination?

Answer 53

Agglutination pattern showing both agglutinated and non-agglutinated cells

Question 54

What does a positive auto-control indicate?

Answer 54

Presence of autoantibodies

Question 55

Why should O cell control be tested in reverse typing?

Answer 55

To help identify Bombay phenotype

Question 56

What should be done if an ABO discrepancy is found?

Answer 56

Investigate patient history, redraw sample, repeat testing

Question 57

Which antigen is present in all ABO blood types?

Answer 57

H antigen