1. MULTIPLE ALLELES,
BLOOD GROUP
and Rh FACTOR

2. Blood and its components
• Liquid fluid consisting of following
components:
a. Cells (45%)
b. Plasma (55%)
c. Serum=plasma-fibrinogen

3. Antigen-Antibody
• Antigen:
The foreign substance that triggers the
production of antibodies.
• Antibodies:
The substances produced in response to
antigens.

4. Agglutination
• The reaction between the antigen and antibody
• Clumping of red blood cells occur in some
cases and in some cases do not

5. Introduction to Blood Group
Systems
• 35 blood group systems are recognized
• Most important ABO blood group system and
Rh system
• M-N system also has little importance
• Classification is based on inherited antigenic
substances

6. M-N blood group system
• This system was discovered by Land Steiner
and Levine(1927)
• Antigens M and N are encoded by
polymorphic genes GYPA and GYPB

7. MN Blood Group System
Types
The system has three blood types:
• MM blood group
• NN blood group
• MN blood group

8. MN Blood Group System

9. MN Antigens Vs Antibodies
• M and N antigens are weakly immunogenic
for humans
• Antibodies against M and N antigens are rare
• Little clinical significance in blood transfusion

10. Multiple Alleles
• A set of three or more altered form of a gene
• An individual posses only two of these allelic
forms
• Example: Alleles encoding the ABO blood
group system

11. ABO Blood Group System
• The most important and well studied blood
group system
• Discovered by Karl Land
• Steiner(1900-1901)

12. ABO Blood Type
• Blood group A
• Blood group B
• Blood group AB
• Blood group O

13. ABO Blood Type
• Determined by the ABO gene, located on
chromosome no . 9
• The gene has three allelic forms IA
IB
and i
• These determine four types of blood groups

14. ABO Blood Group Types
• If A antigen is present, blood group will be A
• If B antigen is present, blood group will be B
• If both A and B antigens are present, blood
group will be AB
• If neither A nor B antigen is present, blood
group will be O

15. Antibodies Against ABO
Antigens
• The immune system form antibodies against
whichever ABO blood group antigens are
present
• For example a person with blood group A will
have B antibodies and so as other

16. Antigens Vs Antibodies

18. Biochemical Basis Of ABO Blood
Group System
• A and B antigens are carbohydrate group
bound to lipid
• The specificity of antigen based on terminal
sugar of carbohydrate
• The one or two terminal sugar added to H
substance determine blood group

19. Biochemical Basis of ABO
Blood Group System
• IA
allele add N-acetyl galactosamine
• IB
allele add terminal glactose
• Heterozygote IA
IB
add both sugar at various
sites on RBCs surface
• The recessive allele i does not add either sugar

20. Difference Between A,B and O
Antigens

21. Importance of ABO Blood
Group System
• Most important test because:
• Antibodies of ABO system present in every
person
• Incompatible blood transfer causes the
intravascular hemolysis of RBCs leading to
death

22. Change In Phenotypic
Expression of ABO Gene
Bombay Phenotype:
• The individuals possess neither A nor B
antigens on their surface
• Phenotypic expression is like O blood group
type

23. Biochemical Basis of Bombay
Phenotype
• Normal persons have H antigen on surface of
RBCs acting as precursor
• Affected individuals do not encode H antigen
• Can receive blood only from H antigen
deficient donors

24. Universal Donors Vs
Universal Acceptors
Universal Donor:
• Can donate their blood to anyone
• Have O negative blood group
Universal Acceptors:
• Can accept blood from anyone
• Have AB positive blood group

25. Rh Blood Group System
• This system also discovered by Karl Land
Steiner(1940)
• Second important blood group system
• The main cause of hemolytic disease of new
born(HDN)

26. Rh Blood Group
• Consists of 49 antigens
• Most significant are D,C,E,c and e
• Commonly used term Rh factor refer to D
antigen on RBCs surface

27. Types of Rh Blood Group
System
• Rh Positive:
Posses Rh antigen on surface of RBCs
• Rh Negative:
Lack Rh antigen on surface of RBCs

28. Erythroblastosis Fetalis
• Hemolytic disease of new born
Occurrence:
• If a mother with Rh-
have a fetus with Rh+
• Mother develop Rh-
antibodies against fetus
Rh+
• These antibodies will react with subsequent
Rh+
fetus
• Lead to bursting of RBC’s

30. Treatment For Erythroblastosis
Fetalis
• Steps are taken to prevent antibodies
production against fetus antigens
• Usually a shot of Rh antibodies are given to
mother within 72 hours of delivery
• Blood Transfusion

31. ABO Blood Group and Rh factor
Determination by Kit Test
• It is the method can be used for the blood
group detection
Principle:
• The ABO and Rh blood grouping system is
based on agglutination reaction
• It is the reaction between Antigens present on
red blood cells and antibodies present in serum

32. Materials Required
Contents:
• Anti-A sera
• Anti-B sera
• Anti Rh-D sera
• Cavity slide
• Mixing Stick
• Blood Lancet
• Spirit/Alcohol

33. Procedure
• Dangle the hand down
• Clean fingers with alcohol
• Sterile lancet and pierce the finger tip and
place blood in cavities
• Add one drop of anti-serum
• Mix the blood and anti-sera
• Observe agglutination

35. Determination of Blood Group on
the basis of Agglutination
Sr.No Anti-A Anti-B Anti Rh-D Blood Group
Slide 1 √ × √ A +ve
Slide 2 × √ √ B+ve
Slide 3 √ √ √ AB+ve
Slide 4 × × √ O+ve

36. Interpretations
• Agglutination observed when blood is mixed
with anti-A reagent then blood group is “A”
• Agglutination observed when blood is mixed
with anti-B reagent then blood group is “B”
• Agglutination observed when Anti-A and
Anti-B reagents then blood group is AB

37. Continued……………
• If no Agglutination is observed then blood
group is “O”
• If agglutination is observed when blood is
mixed with Anti Rh-D reagent, then the
individuals is said to have “+ve” Rh factor.
• If no agglutination is observed when blood is
mixed with Anti Rh-D reagent, then the
individuals is said to have “-ve” Rh factor.