Blood Grouping in Humans, Uses, Disorders- Erythroblastosis fetalis

What do we mean by blood grouping?

The surface of RBC contains certain antigens. It is these antigens on the basis of which the blood groups are decided.
 

Different types of Blood Grouping

  1. ABO blood grouping- chromosome 9 (it has four different types of blood groups- A,B,AB,O) (AB blood group is a very good example of Co-dominance).
  2. Rh Antigen-If Rh antigen present then it is Rh +ve , and if absent then it is Rh -ve
  3. MN blood grouping-  chromosome 4
  4. Duffy antigen- chromosome 1, first blood system antigen to be localized.
  5. Bombay blood group-Chromosome 19. Another antigen present on the RBC is the H antigen. H antigen is necessary for the expression of A,B antigens on the RBC surface. O blood group has got only the H antigen. Now if this antigen is also absent the surface RBC then it is known as the Bombay blood group. 

Landsteiner's Law

I - If an antigen is present on the RBC corresponding antibody must be absent in the plasma.
     eg- A person with A blood group will not have A antibody in his plasma.
     There is no exception to this law.

II- If antigen is absent from the RBC surface the corresponding antibody must be present in plasma.
     
Exception to law II- Rh blood group-  
Rh-ve people don't have Rh antibodies until and unless they are exposed to Rh positive blood.

Erythroblastosis fetalis



Some Important Points-

  • ABO incompatibility rarely produces hemolytic disease of the newborn(Erythroblastosis Fetalis) because the anti-bodies of this system belong to IgM category gamma globulins. These cannot cross the placental barrier.
  • Direct (Major) Cross Matching: Donor cells tested with recipient plasma.
  • Indirect (Minor) Cross Matching: Donor plasma is tested against the red cells of recipient.
  • Most common blood group in India is B+ve
  • Universal blood donor- O -ve (bombay blood group is even better)
  • Universal Recipient- AB +ve 
  • ABO blood grouping can be used to settle paternal disputes, but there is disadvantage. It can confirm that the person is not the father but cannot confirm he is the father.

    Comments

    1. Unknown27 March 2021 at 19:48

      This is an absolute lifesaver for the Hematology viva.😄

      ReplyDelete
    2. Unknown27 March 2021 at 22:08

      So simplified and informative. Thank you sir😀

      ReplyDelete

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