Rh Blood Group

Question 1

Who discovered the ABO blood group system?

Answer 1

Karl Landsteiner in 1900-1901.

Question 2

What event in 1939 led to the discovery of the Rh system?

Answer 2

Levine and Stetson investigated a hemolytic transfusion reaction in a pregnant woman.

Question 3

Who discovered the Rh factor in 1940?

Answer 3

Landsteiner and Wiener.

Question 4

Why is the Rh system important in transfusion medicine?

Answer 4

It is the second most important blood group system and can cause hemolytic reactions.

Question 5

What is the main antigen that determines Rh positivity?

Answer 5

The D antigen.

Question 6

What does Fisher-Race’s DCE terminology represent?

Answer 6

Three closely linked genes: D, C, and E.

Question 7

What does Wiener’s Rh-Hr terminology propose?

Answer 7

A single gene that produces multiple antigens.

Question 8

What is Rosenfield’s numeric system for Rh?

Answer 8

Assigns numbers to antigens based on order of discovery (e.g., Rh1 = D, Rh2 = C).

Question 9

What is the ISBT numeric designation for the D antigen?

Answer 9

4001

Question 10

What are the most common Rh haplotypes in Caucasians?

Answer 10

DCe (42%), dce (37%), DcE (14%).

Question 11

Which genes code for Rh antigens?

Answer 11

RHD and RHCE.

Question 12

What is the function of the RHAG gene?

Answer 12

Encodes Rh-associated glycoprotein, which stabilizes Rh proteins.

Question 13

What is the primary difference between RHD and RHCE?

Answer 13

RHD determines D antigen presence, while RHCE determines C/c and E/e.

Question 14

What are the four possible RHCE alleles?

Answer 14

RhCe, RhcE, Rhce, RhCE.

Question 15

What is the role of Rh proteins in RBCs?

Answer 15

Structural integrity and ammonia/CO₂ transport.

Question 16

What is a molecular cause of Rh-negative phenotypes?

Answer 16

RHD gene deletion or mutations.

Question 17

What is a weak D phenotype?

Answer 17

A reduced expression of the D antigen due to genetic variation.

Question 18

What is a partial D phenotype?

Answer 18

Missing or altered D epitopes due to hybrid genes.

Question 19

What is the Del phenotype?

Answer 19

Extremely low D antigen expression, common in Asians.

Question 20

What is the Tippett genetic model?

Answer 20

A two-locus theory: one for D and one for Cc/Ee.

Question 21

What causes the weak D phenotype?

Answer 21

Position effect, genetic variant, or D-mosaic.

Question 22

How does C in trans to RHD affect D antigen expression?

Answer 22

It weakens D antigen due to steric hindrance.

Question 23

What is the difference between weak D and partial D?

Answer 23

Weak D has fewer normal D sites, while partial D lacks specific epitopes.

Question 24

Can weak D individuals produce anti-D?

Answer 24

Rarely, because the antigen is present but in low amounts.

Question 25

Why is the Du test performed?

Answer 25

To detect weak D individuals.

Question 26

What is Rhnull syndrome?

Answer 26

A condition where no Rh antigens are present, leading to hemolytic anemia.

Question 27

What causes Rhnull syndrome?

Answer 27

Mutations in RHAG or RH genes.

Question 28

What is Rhmod syndrome?

Answer 28

Partial suppression of Rh antigen expression.

Question 29

Why do Rhnull RBCs have membrane abnormalities?

Answer 29

Lack of Rh proteins disrupts membrane integrity.

Question 30

Name three rare Rh antigens.

Answer 30

Rh17, Rh32, and Rh43.

Question 31

What type of immunoglobulin are Rh antibodies?

Answer 31

IgG.

Question 32

Do Rh antibodies cross the placenta?

Answer 32

Yes, they can cause HDFN.

Question 33

What happens if an Rh-negative mother develops anti-D?

Answer 33

It can attack fetal Rh-positive RBCs, causing HDFN.

Question 34

How can Rh alloimmunization be prevented?

Answer 34

Administering Rh immunoglobulin (RhIg) to Rh-negative mothers.

Question 35

When should RhIg be given during pregnancy?

Answer 35

At 28 weeks and within 72 hours after birth if the baby is Rh-positive.

Question 36

Can an Rh-negative person receive Rh-positive platelets?

Answer 36

Yes, but there is a small risk of sensitization.

Question 37

Why should Rh-negative females of childbearing age receive Rh-negative blood?

Answer 37

To prevent alloimmunization and future pregnancy complications.

Question 38

What is anamnestic response in Rh antibodies?

Answer 38

A rapid reappearance of anti-D after re-exposure to Rh-positive RBCs.

Question 39

What is the most common cause of severe HDFN?

Answer 39

Anti-D.

Question 40

Can an Rh-negative mother have an Rh-positive child?

Answer 40

Only if there was an error in testing or a rare genetic event.

Question 41

How is weak D detected?

Answer 41

Indirect Antiglobulin Test (IAT).

Question 42

What is the confirmatory test for Rh typing?

Answer 42

Du test (IAT-based).

Question 43

Why must Du-positive blood donors be labeled as Rh-positive?

Answer 43

To prevent transfusion to Rh-negative recipients.

Question 44

What is the primary cause of partial D phenotypes?

Answer 44

Hybrid RHD-RHCE genes.

Question 45

Why can partial D individuals develop anti-D?

Answer 45

They lack some D epitopes and may recognize transfused D as foreign.

Question 46

What is the best method for Rh antigen detection?

Answer 46

Molecular testing.

Question 47

What reagent is used in the Direct Antiglobulin Test?

Answer 47

Anti-human globulin (AHG).

Question 48

What does a positive DAT indicate?

Answer 48

The presence of antibodies or complement on RBCs.

Question 49

Why is Rh typing important in newborns?

Answer 49

To determine risk for HDFN.

Question 50

How does Rh typing differ from ABO typing?

Answer 50

Rh typing does not require reverse grouping.

Question 51

What is the -D- phenotype?

Answer 51

A rare phenotype with only D antigen and no other Rh antigens.

Question 52

What is Rh17?

Answer 52

An Rh antigen present on all Rh-positive cells but absent in some rare individuals.

Question 53

What happens if an Rh-negative individual has a weak D result?

Answer 53

Consider molecular testing to determine genotype.