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Abo blood groups

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The Blood Group Systems Dr. Yogendra Vijay Resident doctor SMS Medical college,Jaipur (Rajasthan)
Transcript
Page 1: Abo blood groups

The Blood Group Systems

Dr. Yogendra Vijay

Resident doctor

SMS Medical college,Jaipur

(Rajasthan)

Page 2: Abo blood groups

•The blood group you belong to depends on what you have inherited from your parents.

Page 3: Abo blood groups

• There are more than 20 genetically determined blood group systems known today

• The AB0 and Rhesus (Rh) systems are the most important ones used for blood transfusions.

• Not all blood groups are compatible with each other. Mixing incompatible blood groups leads to blood clumping or agglutination, which is dangerous for individuals.

Page 4: Abo blood groups

Blood group AIf you belong to the blood group A, you have A antigens on the surface of your RBCs and B antibodies in your blood plasma.

Blood group BIf you belong to the blood group B, you have B antigens on the surface of your RBCs and A antibodies in your blood plasma.

AB0 blood grouping system

Page 5: Abo blood groups

Blood group ABIf you belong to the blood group AB, you have both A and B antigens on the surface of your RBCs and no A or B antibodies at all in your blood plasma.

Blood group OIf you belong to the blood group O, you have neither A or B antigens on the surface of your RBCs but you have both A and B antibodies in your blood plasma.

Page 6: Abo blood groups

• The "A“ and "B" antigens are also produced

by some other plants and microorganisms. Thus, individuals who do not recognize one or more of these antigens as "self" will produce antibodies against the plant or microbial antigens.

• These antibodies will also react with human antigens of the same kind whether introduced via a blood transfusion or a tissue graft.

Page 7: Abo blood groups

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

7

Page 8: Abo blood groups

• The ABO gene is autosomal (the gene is not on either sex

chromosomes)

• The ABO gene locus is located on the chromosome 9.

• Each person has two copies of genes coding for their ABO blood

group (one maternal and one paternal in origin)

• A and B blood groups are dominant over the O blood group

• A and B group genes are co-dominant

ABO inheritance and genetics

Page 9: Abo blood groups

Principles of Heredity

Antigens and enzymes are genetically controlled

Genes: responsible for transfer of hereditable material

Genes are found on chromosomes, which are found in the nucleus of every cell

Human Cells contain 46 chromosomes with the exception of the egg and sperm, which contain only 23.

23 of these chromosomes are inherited from mother

23 of these chromosomes are inherited from father

Page 10: Abo blood groups

Genes Come in Pairs

The position a gene occupies on a chromosome is called a locus.

Genes for the same trait are located at the same locus on both the mother and the father’s chromosomes.

Alternative forms of genes that influence a given characteristic are called alleles.

Father: allele for brown eyes

Mother: allele for blue eyes

Page 11: Abo blood groups

Blood Types are Genetic

A and B Blood Types are Dominant

Dominant: Characteristic is shown

Blood Type O is Recessive

Recessive: Characteristic is hidden

Recessive characteristics only appear when both alleles are recessive

Homozygous recessive OO

Page 12: Abo blood groups

Phenotype V. Genotype

Phenotype: individual’s outward characteristics

Genotype: individual’s pair of allele genes together

Example:

Phenotype Genotype

Type B Blood Could be BO or

BB depending

on parents

Page 13: Abo blood groups

Important Parts for Forensic Science

Red Blood Cells—because of their importance in blood typing

Serum—because of its’ importance in carrying antibodies

Page 14: Abo blood groups

ABO and H Antigen Genetics

Genes at three separate loci control the occurrence and

location of ABO antigens

The presence or absence of the A, B, and H antigens is

controlled by the H and ABO genes

Page 15: Abo blood groups

Location

The presence or absence of the ABH antigens on the red

blood cell membrane is controlled by the H gene

The presence or absence of the ABH antigens in

secretions is indirectly controlled by the Se gene

Page 16: Abo blood groups

ABO Antigen Genetics

H gene – H and h alleles (h is an amorph)

Se gene – Se and se alleles (se is an amorph)

ABO genes – A, B and O alleles

Page 17: Abo blood groups

H Antigen

The H gene codes for an enzyme that adds the sugar

fucose to the terminal sugar of a precursor substance

(PS)

The precursor substance (proteins and lipids) is formed

on an oligosaccharide chain (the basic structure)

Page 18: Abo blood groups

RBC Precursor Structure

Glucose

Galactose

N-acetylglucosamine

Galactose

Precursor

Substance

(stays the

same)

RBC

Page 19: Abo blood groups

Formation of the H antigen

Glucose

Galactose

N-acetylglucosamine

Galactose

H antigen

RBC

Fucose

Page 20: Abo blood groups
Page 21: Abo blood groups

H antigen

The H antigen is the foundation upon which A and B

antigens are built

A and B genes code for enzymes that add an

immunodominant sugar to the H antigen

Immunodominant sugars are present at the terminal ends

of the chains and confer the ABO antigen specificity

Page 22: Abo blood groups

A and B Antigen

The “A” gene codes for an enzyme (transferase) that adds N-acetylgalactosamine to the terminal sugar of the H antigen

N-acetylgalactosaminyltransferase

The “B” gene codes for an enzyme that adds D-galactose to the terminal sugar of the H antigen

D-galactosyltransferase

Page 23: Abo blood groups

Formation of the A antigen

Glucose

Galactose

N-acetylglucosamine

Galactose

RBC

FucoseN-acetylgalactosamine

Page 24: Abo blood groups

Formation of the B antigen

Glucose

Galactose

N-acetylglucosamine

Galactose

RBC

FucoseGalactose

Page 25: Abo blood groups

Genetics

The H antigen is found on the RBC when you have the

Hh or HH genotype, but NOT from the hh genotype

The A antigen is found on the RBC when you have the

Hh, HH, and A/A, A/O, or A/B genotypes

The B antigen is found on the RBC when you have the

Hh, HH, and B/B, B/O, or A/B genotypes

Page 26: Abo blood groups

Group O Group A

Many H

antigen sites

Fewer

H antigen

sites

A

A A

AA

Most of the H antigen sites in a

Group A individual have been

converted to the A antigen

Page 27: Abo blood groups

ABO Antigens in Secretions

Secretions include body fluids like plasma, saliva,

synovial fluid, etc

Blood Group Substances are soluble antigens (A, B, and

H) that can be found in the secretions. This is

controlled by the H and Se genes

Page 28: Abo blood groups

Secretor Status

The secretor gene consists of 2 alleles (Se and se)

The Se gene is responsible for the expression of the H

antigen on glycoprotein structures located in body

secretions

If the Se allele is inherited as SeSe or Sese, the person is

called a “secretor”

80% of the population are secretors

Page 29: Abo blood groups

Secretors

Secretors express soluble forms of the H antigen in secretions that can then be converted to A or B antigens (by the transferases)

Individuals who inherit the sese gene are called “nonsecretors”

The se allele is an amorph (nothing expressed)

sese individuals do not convert antigen precursors to H antigen and has neither soluble H antigen nor soluble A or B antigens in body fluids

Page 30: Abo blood groups

Secretor Status Summary

The Se gene codes for the presence of the H antigen in

secretions, therefore the presence of A and/or B

antigens in the secretions is contingent on the

inheritance of the Se gene and the H gene

Se gene (SeSe

or Sese)

H antigen in

secretions

A antigen

B antigen

se gene (sese) No antigens secreted

in saliva or other

body fluids

and/or

Page 31: Abo blood groups

ABO Subgroups

ABO subgroups differ in the amount of antigen present on the red blood cell membrane

Subgroups have less antigen

Subgroups are the result of less effective enzymes. They are not as efficient in converting H antigens to A or B antigens (fewer antigens are present on the RBC)

Subgroups of A are more common than subgroups of B

Page 32: Abo blood groups

Subgroups of A

The 2 principle subgroups of A are: A1 and A2

Both react strongly with reagent anti-A

To distinguish A1 from A2 red cells, the lectin Dolichos

biflorus is used (anti-A1)

80% of group A or AB individuals are subgroup A1

20% are A2 and A2B

Page 33: Abo blood groups

A2 Phenotype

Why is the A2 phenotype important?

A2 and A2B individuals may produce an anti-A1

This may cause discrepancies when a crossmatch is done (incompatibility)

What’s the difference between the A1 and A2 antigen?

It’s quantitative

The A2 gene doesn’t convert the H to A very well

The result is fewer A2 antigen sites compared to the many A1 antigen sites

Page 34: Abo blood groups

A1 and A2 Subgroups*

Anti-A

antisera

Anti-A1

antisera

Anti-H

lectin

ABO

antibodies

in serum

# of

antigen

sites per

RBC

A14+ 4+ 0 Anti-B 900 x103

A24+ 0 3+ Anti-B &

anti-A1

250 x103

*Adapted from Flynn, J. (1998). Essentials of Immunohematology

Page 35: Abo blood groups

Other A subgroups

There are other additional subgroups of A

Aint (intermediate), A3, Ax, Am, Aend, Ael, Abantu

A3 red cells cause mixed field agglutination when

polyclonal anti-A or anti-A,B is used

Mixed field agglutination appears as small agglutinates

with a background of unagglutinated RBCs

They may contain anti-A1

Page 36: Abo blood groups

B Subgroups

B subgroups occur less than A subgroups

B subgroups are differentiated by the type of reaction

with anti-B, anti-A,B, and anti-H

B3, Bx, Bm, and Bel

Page 37: Abo blood groups

ABO Blood Group:ABO Antibodies

Page 38: Abo blood groups

Landsteiner’s Rule:

Normal, Healthy

individuals possess

ABO antibodies to

the ABO antigen

absent from their

RBCs

Page 39: Abo blood groups

Blood Group Systems

Most blood group systems (ABO and others) are made up of:

An antigen on a red cell and the absence of it’s corresponding antibody in the serum (if you’re A, you don’t have anti-A)

If you do NOT have a particular antigen on your red cells then it is possible (when exposed to foreign RBCs) to illicit an immune response that results in the production of the antibody specific for the missing antigen

Page 40: Abo blood groups

ABO

The ABO Blood Group System

does NOT require the presence of

a foreign red blood cell for the

production of ABO antibodies

ABO antibodies are “non-red

blood cell stimulated” probably

from environmental exposure and

are referred to as “expected

antibodies”

Page 41: Abo blood groups

Anti-A1

Group O and B individuals contain

anti-A in their serum

However, the anti-A can be

separated into different

components: anti-A and anti-A1

Anti-A1 only agglutinates the A1

antigen, not the A2 antigen

There is no anti-A2.

Page 42: Abo blood groups

Anti-A,B

Found in the serum of group O

individuals

Reacts with A, B, and AB cells

Predominately IgG, with small

portions being IgM

Anti-A,B is one antibody, it is

not a mixture of anti-A and

anti-B antibodies

Page 43: Abo blood groups

ABO antibodies

IgM is the predominant antibody in Group

A and Group B individuals

Anti-A

Anti-B

IgG (with some IgM) is the predominant

antibody in Group O individuals

Anti-A,B (with some anti-A and anti-B)

Page 44: Abo blood groups

ABO antibody facts

Reactions phase: Room

temperature

Complement can be activated with

ABO antibodies (mostly IgM, some

IgG)

High titer: react strongly (4+)

Page 45: Abo blood groups

ABO Antibodies

Usually present within the first 3-6

months of life

Stable by ages 5-6 years

Decline in older age

Newborns may passively acquire maternal

antibodies (IgG crosses placenta)

Reverse grouping (with serum) should

not be performed on newborns or cord

blood

Page 46: Abo blood groups

Paternity Tests

No blood group can be present in a child without being present in one of the parents

Paternity tests can be resolved in this way unless disputed fathers have the same blood type

Paternity tests can also be determined by using DNA testing

Page 47: Abo blood groups

Blood as Evidence

Blood typing not so useful anymore because of DNA technology

Scientists can now characterize biological evidence by

selecting regions of our DNA

Page 48: Abo blood groups

AUTOSOMAL CHROMOSOME

Dad

Mom

The alleles for Blood group are in the same

place on the chromosome 9. However

the genes have a different code giving the

different blood group

A B

Page 49: Abo blood groups

This meant that if a person inherited one A group gene and one

B group gene their red cells would possess both the A and B

blood group antigens.

These alleles were termed A ( which produced the A antigen ),

B (which produced the B antigen) and O (which was "non

functional"and produced no A or B antigen)

What do co-dominant genes mean?

Page 50: Abo blood groups

Parent

Allele

A B O

A

B

O

Possible Blood group Genotypes

Page 51: Abo blood groups

Parent

Allele

A B O

A AA AB AO

B AB BB BO

O AO BO OO

Possible Blood group Genotypes

Page 52: Abo blood groups

The ABO blood groups

• The most important in assuring a safe blood transfusion.

• The table shows the four ABO phenotypes ("blood groups") present

in the human population and the genotypes that give rise to them.

Blood

Group

Antigens

on RBCsAntibodies in Serum Genotypes

A A Anti-B AA or AO

B B Anti-A BB or BO

AB A and B Neither AB

O Neither Anti-A and anti-B OO

Page 53: Abo blood groups

The ABO Blood Group System

Laboratory Determination of the

ABO System

Page 54: Abo blood groups

METHODS OF ABO BLOOD GROUPING

1.SLIDE METHOD

2.TUBE METHOD

3.GEL SYSTEM

4.MICROPLATE TECHNIQUE

5.GLASS MICROBEAD METHOD

6.GALILEO METHOD

Page 55: Abo blood groups

Several methods for testing the ABO group of an individual exist. The most common method is:

Serology: This is a direct detection of the ABO antigens. It is the main method used in blood transfusion centres and hospital blood banks.

This form of testing involves two components:

a) Antibodies that are specific at detecting a particular ABO antigen on RBCs.

b) Cells that are of a known ABO group that are agglutinated by the naturally occurring antibodies in the person's serum.

Page 56: Abo blood groups

• Illustration of the forward and reverse grouping reaction patterns of the ABO groups using a blood group tile

Page 57: Abo blood groups

Blood Group

Antigens Antibodies Can give blood to

Can receive

blood from

AB

A

B

O

Page 58: Abo blood groups

Blood Group

Antigens Antibodies Can give blood to

Can receive

blood from

AB A and B None AB AB, A, B, O

A A B A and AB A and O

B B A B and AB B and O

O None A and B AB, A, B, O O


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