The Rh Blood Group System

Question 1

What is the Rh blood group system also called

Answer 1

Rhesus System

Question 2

How was the Rh blood group discovered
(4)

Answer 2

Injected Rhesus monkey cells into a guinea pig

Took blood from these guinea pigs and mixed it’s plasma with human blood

85% of human donors reacted with the guinea pigs blood (rhesus antibody discovered)

A lady had a baby, second pregnancy kept resulting in miscarriages, Rhesus antibody was seen in this women

Question 2

How was the Rh blood group discovered
(4)

Answer 2

Injected Rhesus monkey cells into a guinea pig

Took blood from these guinea pigs and mixed it’s plasma with human blood

85% of human donors reacted with the guinea pigs blood (rhesus antibody discovered)

A lady had a baby, second pregnancy kept resulting in miscarriages, Rhesus antibody was seen in this women

Question 3

Who discovered the Rhesus antibody

Answer 3

Landsteiner and Wiener

(Experiment with monkeys and guinea pigs)

Question 4

Who discovered the Rh antibody in humans?

Answer 4

Levine and Stetson

Question 5

Describe the Levine and Stetson experiment
(5)

Answer 5

Group O lady with one previous kid had a miscarriage and required a transfusion

Transfused with husband’s group O blood

Immune system reaction occurred

She had an anti-D antibody

She was RhD negative and had made anti-D after first pregnancy

Question 6

How is rhesus antigen and Rh antigen different?

Answer 6

In monkeys -> anti LW

In humans -> anti Rh

Question 7

What does RhD negative mean?

Answer 7

Dont have the Rh antigen on rbcs

Question 8

What does RhD positive mean

Answer 8

Have the Rh antigen on rbcs

Question 9

What type of blood do you give if a patient produces anti-D?

Answer 9

You have to give D-Negative blood

Question 10

Why won’t we give D positive to women?

Answer 10

In case a women later want’s to get pregnant

This ensures her first pregnancy will go smoothly -> no immediate immune reaction

Question 11

What are the two ways expression of anti-D can be induced

Answer 11

Pregnancy

After transfusion

Question 12

Comment on C and E sets of alleles
(4)

Answer 12

C, E, c, e

The products of two sets of alleles

Co-dominant genes

Antibodies to these occur as immune events and are typically IgG -> potent -> clinical significance

Question 13

What are the Rh proteins??

Answer 13

A family of non-glycosylated membrane proteins

Question 14

What are the Rh protein genes?

Answer 14

RHD and RHCE

Located on chromosome 1

Question 15

What does RHD express

Answer 15

The D antigen

Question 16

What does RHCE express

Answer 16

The C, c, E and e antigens

Question 17

What is the Fisher-Race theory

Answer 17

Rh antigens are controlled by 3 closely linked loci (D/d, C/c, E/e)

Question 18

What is the Wiener theory

Answer 18

Rh antigens are controlled by alleles at one gene locus (you have one of 6 alleles at at locus)

Question 19

What happens in almost all D negs?

Answer 19

The RHD gene is deleted (dd results)

Question 20

How does the RHD protein differ from that of RHCE?

Answer 20

By 36 amino acids

Question 21

By how much does C differ from c

Answer 21

Differs by 4 amino acids

Question 22

By how much does E differ from e

Answer 22

Differs by 1 amino acid

Question 23

By how much does D differ from d

Answer 23

Differs by 36 amino acids

Question 24

What is special about the amino acid proline

Answer 24

It causes a change in direction in the chain of amino acid This is why C is so different from c

Question 25

What is the CDE haplotype referred to as?

Answer 25

Rz

Question 26

What is the cde haplotype referred to as?

Answer 26

r

Question 27

Do we use a R or r with a big D?

Answer 27

R

Question 28

Do we use a R or r with a small D

Answer 28

r

Question 29

What do we use when we have a big C?

Answer 29

C+D = 1 C+ d = '

Question 30

What do we use when we have a big E?

Answer 30

E + D = 2 E + d = ''

Question 31

What is the haplotype for dCe

Answer 31

r'

Question 32

What is the haplotype for dcE

Answer 32

r''

Question 33

What is the haplotype for dCE

Answer 33

Ry

Question 34

What is the haplotype for Dce

Answer 34

Ro

Question 35

What is the haplotype for Dce

Answer 35

R1

Question 36

What is the haplotype for DcE

Answer 36

R2

Question 37

What are the most common haplotypes in caucasians

Answer 37

R1 r R2 R0

Question 38

What are the most common haplotypes in black populations

Answer 38

R0 r R1 R2

Question 39

What blood group antigen is the most immunogenic?

Answer 39

The D antigen

Question 40

Why should you give RhD negative blood to RhD negative patients

Answer 40

Most RhD negative will produce anti-D antibodies

Question 41

What is ISBT Terminology

Answer 41

International Society of Blood Transfusion Assigns six-digit numbers to each blood group specificity

Question 42

What does the number 004 refer to?

Answer 42

Rh system

Question 43

What is the Rosenfield nomenclature

Answer 43

RH1 = D Rh2 = C Rh3 = E Rh4 = c Rh5 = e

Question 44

What does the ISBT number 002 refer to?

Answer 44

It refers to Rh2 or the C antigen

Question 45

What does Rh: 1,2,-3,4,5 mean?

Answer 45

R1r DCe/dce

Question 46

When might a transfusion reaction occur

Answer 46

Rh antibody levels may be undetectable in a patient for years but they might produce a rapid response upon reexposure to the antigen via transsfusion

Question 47

What is HDFN

Answer 47

Haemolytic disease of the foetus and newborn

Question 48

How does HDFN occur (3)

Answer 48

Mother is RHd negative Baby is Rhd positive Mother is exposed to antigen and produces antibodies during first pregnancy Mother produces antibodies against babies rbcs which pass over through the placenta

Question 49

How do weak antigens occur (3)

Answer 49

Mutation in the amino acid chain of the antigen Antigen can no longer sit correctly into the rbc membrane Charged amino acids cannot sit inside the inner lipid of the cell membrane (this doesn't like charges)

Question 50

Why is it important to identify weak D positives

Answer 50

We don't have much D negative blood so we want to be picking up this D positive so we don't waste blood

Question 51

How do we classify weak antigens

Answer 51

RBCs that only test positive by the indirect antiglobulin test (IAT)

Question 52

What can we use to detect weak antigens other than the indirect antiglobulin test?

Answer 52

Monoclonal reagents

Question 53

Why is weak D antigen seen more in black population

Answer 53

Due to inheritance of a weaker form of the D antigen Often the cDe haplotype

Question 54

What is meant by the position effect of weak D antigens? (4)

Answer 54

A D antigen that appears weak due to a C antigen inherited trans to D Rhce and RhCE as well as RhD and Rhd RhCE will be copied more than RhD Leads to a weaker expression of D

Question 55

What does it mean if alleles are in trans to one another

Answer 55

They are on opposite chromosomes

Question 56

What does it mean if alleles are in cis to one another

Answer 56

They are on the same chromosome

Question 57

What does it mean to be partial D? (3)

Answer 57

Individuals are D positive but are missing parts of the D antigen Individuals may produce antigens towards the missing parts of the D antigen when exposed to it Patients should be given D negative blood

Question 58

What is important to note about partial D blood in hospitals vs donations?

Answer 58

Partial D should be labelled D positive when donated Partial D should be given D negative blood in hospital

Question 59

How many partial D phenotypes are there?

Answer 59

There is 30+ epitopes on antigen D so there is different mutations whereby these epitopes are missing

Question 60

Give an example of a partial D

Answer 60

D6 (partial D)

Question 61

What happens with RhD incompatibility

Answer 61

Possibly fatal Often serious morbidity Leading cause of HDN

Question 62

What is Rh null (3)

Answer 62

The absencce or severe reduction of Rh polypeptide expression An autosomal recessive disorder resulting in haemolytic anaemia and sphcrostomatocytosis Patients produce Rh29 which is linked with autoantibody haemolytic states