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ABO BLOOD GROUP SYSTEM

Introduction•All human blood may look alike but when it is tested using special agents, differences become apparent.

ABO Genes

1 =  A/A           1 = Homozygous APhenotype AGenotype A/ACan Contribute Only

an A Gene to Offspring

2 = A/O2 = Heterozygous APhenotype A Genotype A/0 Can Contribute A or O

Gene to Offspring

White African American

Hispanic

Asian

O + 37% 47% 53% 39%

O - 8% 4% 4% 1%

A + 33% 24% 29% 27%

A - 7% 2% 2% 0.5%

B + 9% 18% 9% 25%

B - 2% 1% 1% 0.4%

AB + 3% 4% 2% 7%

AB - 1% 0.3% 0.2% 0.1%

ABO phenotypes and genotypes

1. Group A phenotype = A/A or A/O genotype

2. Group B phenotype = B/B or B/O genotype

3. Group O phenotype = O/O genotype

4. Group AB phenotype = A/B genotype

Blood Type Inheritance

Parent 1

AB AB

AB

AB

B A A O O O

Parent 2

AB B A O B B A B A O

Possible

bloodtype

ofchild

O + + + + + +

A + + + + + + +

B + + + + + + +

AB + + + +

BIOCHEMISTRY OF THE ABO SYSTEM

Production H Antigens

Production A Antigens

Production B Antigens

Indications for ABO grouping

•Blood Donors•Transfusion recipients•Transplant Candidates and

Donors •Prenatal Patients•Newborns•Paternity testing

BLOOD GROUP

ANTIGEN ANTIBODY

A A anti-B

B B anti-A

AB A and B neither

O neither A norB

anti-A,B

Landsteiner's rules for the ABO Blood Group

• A person does not have antibody to his own antigens

• Each person has antibody to the antigen he lacks (only in the ABO system)

• Below are the four blood groups and the antigens and the expected, naturally-occurring antibodies present.

ABO Typing

Routine ABO TypingReaction of Cells Tested

With

Red Cell ABO

Group

Reaction of Serum Tested

AgainstRever

se ABO

Group

Anti-A Anti-B

A cells

B Cells

0 0 O + + O

+ 0 A 0 + A

0 + B + 0 B

+ + AB 0 0 AB

Discrepancies in ABO typing

• Results of forward and reverse typing must agree before reporting out blood type as seen in the about table.

• If forward and reverse do not agree, must identify cause of discrepancy.

• If cannot resolve discrepancy, must report out blood type as UNKNOWN and give group O blood