QS Study

The word “blood group” refers to the whole blood group system comprising red blood cell (RBC) antigens whose specificity is controlled by a series of genes which can be allelic or linked very closely on the similar chromosome. International Society of Blood Transfusion has recently recognized 33 blood group systems.

Major blood group

  1. ABO blood group/classical blood group system
  2. Rh system
  3. MN system

Apart from ABO and Rhesus system, many other types of antigens have been noticed on the red cell membranes.

ABO system- Based upon the group-specific antigen present on RBC membrane. The ABO system is unique in that whenever the A or B antigens are not present on the red cells, the corresponding antibody is present in the serum/plasma. Anti-A and anti-B alloagglutinins are therefore often referred to as being ‘naturally occurring’. In this system blood group are –

  • Group A
  • Group B
  • Group AB
  • Group O.

Fig: ABO system

Rh System- Based upon the presence or absence of Rh antigen in Blood. In this system, Blood group are – Rh positive and Rh negative. Rhesus grouping adds another dimension. If the red blood cells contain the RhD antigen, they are RhD positive. If they do not, they are RhD negative. This means that there are eight main blood types in the ABO/RhD blood group system.

  • A-positive (A+) occurs in 30 percent of people; A-negative (A-) occurs in 6 percent of people
  • B-positive (B+) occurs in 9 percent of people; B-negative (B-) occurs in 2 percent of people
  • AB-positive (AB+) occurs in 4 percent of people; AB-negative (AB-) occurs in 1 percent of people
  • O-positive (O+) occurs in 39 percent of people; O-negative (O-) occurs in 9 percent of people.

Fig: Rh System

M-N system– Used in paternity determination.

Others – (1) Duffy (2) Kidd (3) Kell (4) Lewis etc.

Name the classical blood group with their antigen and antibody-

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