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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 A Phenotype A Genotype A/A Can Contribute Only an A Gene to Offspring 2 = A/O 2 = Heterozygous A Phenotype A Genotype A/0 Can Contribute A or O Gene to Offspring

White African American HispanicAsian O +37%47%53%39% O -8%4% 1% A +33%24%29%27% A -7%2% 0.5% B +9%18%9%25% B -2%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 1AB BAAOOO Parent 2ABBAOBBABAO Possible blood type of child 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 GROUPANTIGENANTIBODY AAanti-B BBanti-A ABA and Bneither Oneither 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 Typing Reaction of Cells Tested With Red Cell ABO Group Reaction of Serum Tested Against Reverse ABO Group Anti-AAnti-BA cellsB Cells 00O++O +0A0+A 0+B+0B ++AB00

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