MULTIPLE ALLELES AND BLOOD GROUPING

Mr. Dinabandhu Barad, MSc Tutor, SNC, SOA, DTU

MULTIPLE ALLELES
&
BLOOD GROUPING
Presented By:
Mr. Dinabandhu Barad
MSc Tutor, SNC, SOA, DTU

MULTIPLE ALLELES & BLOOD GROUPING
OBJECTIVES:
At the end of the class you will be able to:
• Define allele and multiple alleles
• Explain blood groups
• Recall the KARL LANDSTEINER’s law
• Identify the genotype of the blood groups
• Apply genetics to predict blood group

ALLELE
An Allele is an alternative form of a same gene, located on
same locus on the homologous chromosomes.
Alleles were first defined by Gregor Mendel in the law of
segregation

MULTIPLE ALLELES
• According to Altenburg, “Three or more kinds of gene which
occupy the same locus are referred to as multiple alleles.”
• Multiple alleles are defined as three or more alternative
form of a same gene, located on same locus on the
homologous chromosomes, coding for certain characteristic
in a population.
• EXAMPLE: ABO BLOOD GROUP (Has three alleles)

BLOOD
Blood is a specialized body fluid.
It has four main components:
1. Plasma
2. Red blood cells
3. White blood cells
4. Platelets

ABO BLOOD GROUPS
• ABO blood group in Human
was discovered by KARL
LANDSTEINER in 1901.

ABO BLOOD GROUPS
• Karl Landsteiner (1868-1943),
the Austrian-born American
immunologist.
• He, has been titled as the
“father of immunology”.
• He discovered the blood
groups (ABO) and framed the
Landsteiner’s Law by 1904.

RBC
ABO BLOOD GROUPS
• The ABO system is
characterized by the presence
or absence of antigens on the
surface of Red Blood Cells.

ABO BLOOD GROUPS

LAWS OF KARL LANDSTEINER
1. If an ANTIGEN is present in
the red cells of a blood, the
corresponding ANTIBODY
must be absent from the
plasma.
2. If an ANTIGEN is absent in
the red cells of a blood, the
corresponding ANTIBODY
must be present in the
plasma.

ABO GENOTYPE
Blood
Group
Antigens
Present on
RBCs
Antibody
Present in
plasma
Genotype
A A antigen Anti-B IAIA or IAIO
B B antigen Anti-A IBIB or IBIO
AB
A antigen
B antigen
None IAIB
O None
Anti-A, anti-B,
anti-A,B
IOIO

GENETICS OF ABO BLOOD SYSTEM
• The ABO blood type is inherited in an Autosomal Co-
Dominant fashion.
• The ABO locus is located on chromosome 9 at 9q34.1-q34.2
consisting 18 kb of genomic DNA.
• The A and B alleles differ from each other by seven
nucleotide substitutions
• The gene controlling ABO blood type is labeled as I.
• The alleles are designated as IA, IB and IO (or i).

GENETICS OF ABO BLOOD SYSTEM
• Where, I → Isoagglutinogen (antigen)
• IA → Allele for A antigen
• IB → Allele for B antigen
• IO → Allele for o antigen
• Dominance Hierarchy among alleles; IA = IB > IO
• i.e., Alleles IA & IB are dominant over IO
• Alleles IA & IB are Co-dominant

PREDICTING BLOOD GROUP

QUESTION NO: 1
A father of blood type A and a mother of blood type B. What
blood types are possible in their subsequent children?
SOLUTION
Father’s blood group A : alleles- IAIA or IAIO
Mother’s blood group B: alleles- IBIB or IBIO
Possible combinations:
1. father has IAIA and mother has IBIB
2. Father has IAIA and mother has IBIO
3. Father has IAIO and mother has IBIB
4. Father has IAIO and mother has IBIO

QUESTION NO: 1
1. father has IAIA and mother has IBIB
F/M IB IB
IA IAIB (AB group) IAIB (AB group)

QUESTION NO: 1
2. Father has IAIA and mother has IBIO
F/M IB Io
IA IAIB (AB group) IAIo (A group)
IA IAIB (AB group) IAIo (A group)

QUESTION NO: 1
3. Father has IAIO and mother has IBIB
F/M IB IB
Io IOIB (B group) IOIB (B group)

QUESTION NO: 1
4. Father has IAIO and mother has IBIO
F/M IB IO
IA IAIB (AB group) IAIO (A group)
Io IOIB (B group) IOIO (O group)

QUESTION NO: 1
SOLUTION:
Father’s blood group A : alleles- IAIA or IAIO
Mother’s blood group B: alleles- IBIB or IBIO
ANSWER: A,B,AB,O

QUESTION NO: 2
A father of blood type AB and a mother of blood type O. What
SOLUTION:
Father’s blood group AB : alleles- IAIB
Mother’s blood group O: alleles- IOIO

QUESTION NO: 2
Father has IAIB and mother has IOIO
F/M IO IO
IA IAIO (A group) IAIO (A group)
IB IBIO (B group) IBIO (B group)

QUESTION NO: 2
SOLUTION:
Father’s blood group AB : alleles- IAIB
Mother’s blood group O: alleles- IOIO
ANSWER: A,B

ASSIGNMENT
QUESTION NO: 3
A father of blood type AB and a mother of blood type A. What
QUESTION NO: 4
A father of blood type AB and a mother of blood type AB.
What blood types are possible in their subsequent children?
QUESTION NO: 5
A father of blood type B and a mother of blood type B. What

THANK
YOU

MULTIPLE ALLELES AND BLOOD GROUPING

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