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BLOOD GROUPS & Blood types

BLOOD GROUPS & Blood types. Objectives: 1 . List the various types of blood groups. 2. Understand that the RBC surface antigens A or B, or their absence is responsible for determining the blood groups as A, B AB or O,

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BLOOD GROUPS & Blood types

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  1. BLOOD GROUPS • & • Blood types

  2. Objectives: 1. List the various types of blood groups. • 2. Understand that the RBC surface antigens A or B, or their absence is responsible for determining the blood groups as A, B AB or O, and that these are genetically determined.. • 3. Understand that the plasma contains antibodies of the same name • 4. Explain why a person having a particular blood group (for example group A) can not have antibody of the same type in the plasma. • 5. Compare the distribution of blood groups in the Omani population with some other populations • 6. Describe the importance of the Rhesus blood group, and understand that humans are also classified as Rh+ve or Rh –ve, and that about 95% of Omanis are Rh +ve. • 7. Define the term Rh incompatibility and understand that fetal RBC get hemolysed in this condition. • 8. Define the term “Mismatched transfusion”. • 9. Explain the terms blood grouping and cross matching 10. Define the term “transfusion hazards”.

  3. antigens on RBC blood group antibody in plasma A Type A B B Type B A A & B Type AB nil O (nil) Type O AB

  4. Genetic determination of blood groups • Antigens are genetically determined • Each gene carries • either NO antigen (O) • Antigen A • Antigen B Paired genes (one from each parent when they meet will have i. No antigen + antigen A : Genotype (OA):Blood group A ii. No antigen + antigen B Genotype (OB)Blood group B iii. No antigen + No antigen Genotype (OO)Blood group O iv. Antigen A + antigen B Genotype (AB)Blood group AB v. Antigen A + antigen A Genotype (AA)Blood group A vi. Antigen B + antigen B Genotype (BB)Blood group B

  5. Antibodies: not present at birth. • 2. Develop when small amts of antigens A & B enter body as food, in bacteria etc • Host develops antibodies to these. • 4. Chemically these are Ig G and Ig M imunoglobulins

  6. % distribution of Blood groups in Omani & other populations

  7. Blood transfusion 1. Typing: blood groups of donor and recipient Type A cannot be given to B and vice versa Type O is “universal donor”: no antigen on RBC so no reaction Type AB : universal recipient: no antibodies blood

  8. Type A group (recipient) Antigen A & antibody B Type B group (donor) Antigen B & antibody A + antibody B of recipient will react with antigen B of donor (agglutination) and cause hemolyis of donor cells but Anti A of donor get too diluted to affect A type cells of Recipient. So recipient cells not affected significantly • Clinical presentation of mismatched transfusion: • Donor RBCs affected • Immediate hemolysis : chills rigors, acute renal failure; shock • Delayed hemolysis: jaundice as macrophages digest the agglutinated • RBCs

  9. To avoid this mismatch: Blood grouping and typing is done 1. Drop of recipient blood and donor blood separately mixed with a drop of anti A and anti B 2. Observe for agglutination and confirm group type Then select donor type. Suppose A is selected as donor for recipient who is type A: Cross matching is to be done Donor RBCs + recipient’s serum to ensure that some other antibodies are not present in recipient blood

  10. Blood Grouping and typing

  11. Rh blood group (from Rhesus monkey) • Those with antigen on RBC: Rh+ve 90-95% population is Rh +ve No anti Rh antibodies in plasma • Those WITHOUT this antigen: Rh –ve. No antibodies in plasma (no spontaneous development of anti Rh) • Rh -ve given Rh +ve blood: antibodies develop • Next transfusion of Rh +ve to the same person: anti-bodies destroy RBCs

  12. Hemolytic disease of the new born • Mother Rh –ve + Father Rh +ve • Fetus Rh +ve • Some mixing of mother and fetal blood at delivery • Mother develops anti-body to Rh antigen of fetus • Next pregnanacy: antibody from mother passes palental barrier and affects RBC of fetus Hemolytic disease of the new born .Varied severity from mild hemolysis to death

  13. Uncommon blood groups • M, N, Duffy • Bombay Blood • Useful for genetic testing in Forensic Medicine • Usually titre too low to cause any problems

  14. Summary • Types of blood groups • Source of antigens and antibodies • Blood groups of Omani population vis-à-vis others • Blood grouping qnd crossmatching • Effects of mismatched transfusions • Rh blood group and hemolytic disease of the new born

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