What is the most uncommon blood type? Rhnull, the rarest blood type is found in only 44 people worldwide, it lacks all of the 61 possible antigens in the Rh system.

Rarest blood type on earth?
Rarest blood type on earth?

You’re probably aware that you could have A, B, AB or O blood, and that your blood can be positive or negative. But that’s not the whole story.

Rhnull is the rarest blood type that was first detected in an Australian aborigine, in 1961. This rare blood type is essentially a genetic mutation that causes Rh antigen absence. Red blood cells lacking Rh / RhAG proteins have structural abnormalities and cell membrane defects that can result in hemolytic anemia.

Individuals with Rhnull blood type share a similarity with those of type O: both are universal donors, but can only receive a transfusion from the same blood type. 

In the British town of Filton, the International Blood Group Reference Laboratory (IBGRL) has a database with carriers of the rare blood type to ensure that no carrier who needs a donation is left without it. 

The initiative has a serious drawback: Rhnull carriers reside in countries as far apart as Japan, Brazil, Ireland, and the United States, making it difficult to move a bag if needed urgently. In case someone with Rh null has to undergo a scheduled surgery, blood is extracted beforehand and stored for 45 days in case it is necessary.

What are the most common blood types in the world?

As for the most common types, A, B, AB and O, with their positive and negative Rh variants, the most frequent in the world are A+, O+ and B+, but the distribution varies greatly by country. 

For example, in the United States, 37.4% of the population is O-positive, 35.7% is A-positive and 8.5% is B-positive. These proportions are similar in European countries. On the other hand, B+ is very abundant in countries such as Saudi Arabia (33%), India (31%), Japan (20%) or Taiwan (24%). 

The O negative blood type, a universal donor, has more presence in Europe, where it ranges from 6% in France, 7% in Germany, and 9% in Spain. In Asia, on the other hand, it is very rare. For example, only 2% in India, and 0.15% in Japan.

Your blood type is define by the antigens present in your blood, 2019.
Your blood type is define by the antigens present in your blood.

The way blood types are defined

Antigens are anything that can elicit a response from your body’s self-defense system, though your immune system normally ignores the ones that belong to you. And you can find antigens on cells throughout your body, with different cells having different combinations of antigens.