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The Rarest Blood Type in the ABO Blood System

Updated on June 13, 2016
Vials being filled with donor blood
Vials being filled with donor blood | Source

Knowledge of the ABO and Rhesus blood systems is very important for human blood transfusions. Several other blood systems have been identified and these are also very important during pre-transfusion testing.

For blood transfusion to be successful, the donor’s blood must be compatible with the recipient. In blood banks and hospitals, supply problems are more frequent for rare blood types than they are for common blood types. In this article, to look at the rarest blood type, we will focus on the ABO and the Rh blood systems.

The letters A, B and O are used to denote blood types. + and - signs are used to denote the present and absence of the Rh factor. Here's more about the ABO blood-typing system.

What is the Rarest Blood Type?

The tables and figures below show the percentage of the world’s population with each blood type. Table 2 and figure 2 separate the information for Rh- and Rh+ while table 1 and figure 1 where produced without distinguishing between Rh- and Rh+.

Type
%
O
43.9%
A
34.8%
B
16.6%
AB
5.1%
Table1. Approximate Distribution of ABO Blood Group Phenotypes to Identify the Rarest Blood Type

The Rarest Blood Type (Not Stratified by Rhesus Factor)


Approximately 43.9%, 34.8%, 16.6% and 5.1% of the world’s population have blood groups O, A, B and AB respectively.


Figure 1. Approximate Distribution of ABO Blood Group Phenotypes to Identify the Rarest Blood Type
Figure 1. Approximate Distribution of ABO Blood Group Phenotypes to Identify the Rarest Blood Type | Source

Without stratification (separating) by Rh factor, from table 1 and figure 1, you can clearly see that blood type AB has the lowest percentage (5.1%) with respect to other blood types in the ABO system.

AB is the rarest blood type if you pool both Rh+ and Rh- together. However, we are not going to stop here. The section below presents the percentages but this time they are shown by Rh- and Rh+ (separately).

Type
Rh+
Rh-
O
36.4%
4.3%
A
28.3%
3.5%
B
20.6%
1.4%
AB
5.1%
0.5%
Table 2. Approximate Distribution of ABO Blood Group and Rh factor (Phenotypes) to identify the rarest blood type

The Rarest Blood Type Stratified by Rhesus factor

Presenting the data by Rh factor gives a more interesting result.

About 36.4%, 28.3%, 20.6%, 5.1%, 4.3%, 3.5%, 1.4% and 0.5% of the world’s population have blood groups O+, A+, B+, AB+, O-, A-, B- and AB- respectively. So, after stratification by Rh factor, you can clearly see that blood type AB- has the lowest frequency in the world.

Figure 2. Aproximate Distribution of ABO Blood Group and Rh factor (Phenotypes) to identify the rarest blood type
Figure 2. Aproximate Distribution of ABO Blood Group and Rh factor (Phenotypes) to identify the rarest blood type | Source

Conclusion

You can say that among the ABO types, AB- is the rarest blood type in humans. However, the second most rare blood type is not AB+ (approx. 5.1%). In fact all the Rh-negative blood groups are rarer than the AB+ blood group. Therefore, in general we can also say that Rh- blood types are rarer than Rh+ blood types.

Data on the frequency distribution may change with time. Therefore, It is likely that newer data is available on the percentage of the population per ABO/Rh blood types.

What is your blood type?

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    • DREAM ON profile image

      DREAM ON 3 years ago

      Blood we all have it and we never think about it. Thanks for sharing. So now I have a bloody idea what different types there are and that reminds me it's time to give blood once again.I try to give as often as I can sometimes I forget. Have a good day.

    • anatomynotes profile image
      Author

      Edmund Custers 3 years ago

      It is great that you are helping those in need by donating blood. Thanks for stopping by. Have a great day!

    • simul 2 years ago

      I am ab negative

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