This document summarizes ABO and Rh(D) blood grouping systems. It discusses the key points of: - The ABO system including the antigens, antibodies produced, and inheritance patterns. Group O is the universal donor. - The Rh system focuses on the D antigen. About 85% of people are Rh positive. Sensitization can be prevented with anti-D immunoglobulin. - Testing methods for ABO and Rh(D) typing including cell typing with monoclonal antibodies and serum typing. Weak D phenotypes require additional testing to determine Rh status. - Clinical significance of blood group matching for transfusions to prevent hemolytic transfusion reactions. Group AB is the universal recipient.

1. Blood Grouping
DR. RAFIQ AHMAD

2. ABO & Rh(D) Blood Groups

3. The ABO System
 Discovered in 1901 by Dr. Karl
Landsteiner
 4 Main Phenotypes (O, A, B, AB,)
 ABO gene located on long arm of
chromosome 9
- ABO, Hh, Sese

4. The ABO Antigens
 Added to Proteins or Lipids in Red Cells
 Substrate Molecule is H (fucose)
 A antigen is N-acetyl-galactosamine (GalNAc)
 B antigen is Galactose (Gal)
 A and B genes code for transferase enzymes

5. Blood group (or blood type)

6. ABO group Biochemistry

7. ABO Sub groups
ABO Antibodies
 Antibodies produced to “non-self”
 Produced after first few months of life
 A & B people have mainly IgM
 O people have IgG
 May fade in old age
A: A1, A2, A3, Ax, Am, Ael …, A(B)
B: B3, Bx, Bm…, B(A)

8. Inheritance of ABO Groups
Allele from
the mother
Allele from
the father
Genotype of
offspring
Blood types of
offspring
A A AA A
A B AB AB
A O AO A
B A AB AB
B B BB B
B O BO B
O O OO O

9. Distribution of ABO Groups
Population
O A B AB
Aborigines 61 39 0 0
Basques 51 44 4 1
Blackfoot (N. Am. Indian) 17 82 0 1
Saudies (Eastern Province) 49 27 19 5
Chinese-Canton 46 23 25 6
Chinese-Peking 29 27 32 13
English 47 42 8 3
Hawaiians 37 61 2 1
Irish 52 35 10 3
Mayas 98 1 1 1
Navajo (N. Am. Indian) 73 27 0 0
Peru (Indians) 100 0 0 0
United Kingdom (GB) 47 42 8 3
USA (blacks) 49 27 20 4
USA (whites) 45 40 11 4

11. Distribution of the A allele

12. Distribution of the B Allele

13. Distribution of the O Allele

14. ABO Typing
 Cell Group
 Test Washed Cells With:
 Monoclonal Anti-A
 Monoclonal Anti-B
 Inert control
 Agglutination is a positive
result
 Reverse Group
 Test plasma/serum with:
 Known A1 cells
 Known B cells
 Known O cells
 ? Known A2 cells
 Reactions may be weaker
than cell group

15. Significance of ABO Group
 ABO mismatched transfusions:
 Rare
 May be life threatening
 Can be caused by technical or clerical error
 Intravascular haemolysis
 More severe in group O patients

16. Universal Donor and Recipient
 Universal Donor
 Group O
 Carries no A or B
antigens
 Packed and processed
units have little antibody
 Universal Recipient
 Group AB
 Patient has no anti-A or
anti-B present
 Cannot lyse any
transfused cells
 Beware: other
antibodies may be
present
Patient’s own group should always be preferred

17. The Rh(D) Antigen
 Rh is the most complex system, with over 56
antigens
 Discovered in 1940 after work on Rhesus
monkeys
 Subsequently discovered to be unrelated to
monkeys
 Rh gene located on short arm of chromosome 1
 In mid 1940’s other Rh antigens C, c, E, and e
were discovered

19. Simple Genetics of Rh(D)
 97% of asians are Rh(D) pos
 The antithetical antigen d has not been found
 The d gene is recessive:
 Dd, dD, DD, persons are Rh(D) pos
 Only dd persons are Rh(D) neg

20. Distribution of Rh(D) Types
Population Rh(D) pos Rh(D) neg
Caucasian
(Saudis), E Pro.
86%
(90.5)
14%
(9.5)
African-American 95% 5%
Oriental >99% <1%

21. Significance of Rh(D)
 80% of Rh(D) neg persons exposed to Rh(D) pos
blood will develop anti-D
 Anti-D can also be stimulated by pregnancy with
an Rh(D) positive baby
 Sensitisation can be prevented by the use of anti-D
immunoglobulin, antenatally and post natally
 Rh(D) neg females of childbearing potential
should never be given Rh(D) positive blood
products

22. Inheritance
 ABO & Rh genes are not linked
 ABO & Rh(D) type are inherited independently
For example:
An A Rh(D) pos mother
and a B Rh(D) pos father
could have an O Rh(D) neg child

23. Rh Typing
Routine Rh typing
for donors and
patients involves
typing for only the
D antigen.

24. D Testing
 Routine D antigen testing involves testing the
patient RBCs with anti-D commercial antisera
 If the D antigen is present, it should agglutinate
strongly with anti-D at Immediate Spin (IS)
 If you’re Rh+, you have the D antigen
 If you’re Rh-, you do not have the D antigen

25. Weak D phenotype
 Some D-positive RBCs DO NOT react at
Immediate Spin using commercial anti-D
 In these cases, AHG testing is needed to determine
the D status

26. Weak D testing
 If negative at IS, patient cells and anti-D reagent are
incubated at 37° for 20 minutes, then centrifuge
 If still negative, wash x3 and add AHG
 If negative, add CC and report as Rh negative (if CC
agglutinate)
 If positive, report as Weak D Positive
Patients who require AHG testing to
determine the presence of the D
antigen are called “Weak D
Positive”

27. Weak D (Du
) Phenotype
 Weak D can be inherited in three ways:
 Incomplete/Partial antigen (D mosaic)
 Due to the position effect
 Weakened expression of D

28. Partial D (D Mosaic)
 Missing one or more parts of the D antigen
 Since the antisera is specific for the whole D
antigen, a weak reaction may result if patient has a
partial antigen
 Why is Partial D is significant?
 If the patient is transfused with D positive red
cells, they may develop an anti-D alloantibody*
to the part of the antigen (epitope) that is missing
* alloantibody- antibody produced with specificity other than self

29. Position Effect
 Gene interaction effect
 C allele is in trans position to D allele
 Does not occur when C is in cis position
 Steric hindrance causes the anti-D reagent to
weakly attach (C antigen crowds the D antigen)

30. Inheritance of ABO and Rh(D)
Mother
Group A AO
Rh(D) pos Dd
Father
Group B BO
Rh(D) pos Dd
Group A AO
Rh(D) pos Dd
Group B BO
Rh(D) pos Dd
Group O OO
Rh(D) neg dd

31. AABB Standards
 Require weak D testing on all donor red blood cells that
do not agglutinate at IS
 DO NOT require weak D testing on recipient blood
 each facility has their own protocol
 If only IS is performed and patient is negative, they will
receive negative units
 However, some labs don’t like to waste D-negative units, so
they take the test to AHG
 If the patient is positive, they may receive D-positive units
(it would be rare that the patient is a Partial D)

32. The end!!
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