Rare Blood Types

The first blood transfusion on humans was performed in the 1600s, with animal blood and the result was disastrous. It was in the 1800s, that James Blundell proposed the concept of using human blood transfusion for human beings. However, it was only in the early 1900s, that the four types of blood groups, were identified by Karl Landsteiner. This led to successful blood transfusions in humans and better results were produced when the type of blood was the same in the donor and receiver.

Blood Types
Before understanding the term 'rare blood group', we need to understand the basics about blood group types. Blood group type is inherited from one's parents just like how skin color, eye color, etc. are inherited. It's just something that is passed down through the genes. Now, blood contains red blood cells (RBCs), which feature specific antigens (proteins, carbohydrates, glycoproteins or glycolipids) on their surface. There are several types of such antigens, depending on which blood group classification is carried out.

Depending on the type of antigens present, such as A,B, AB or none, along with the Rhesus factor, the blood groups are determined. For example, blood group 'A' is called so because it contains antigen A and antibodies B in the plasma. Blood group 'B' contains antigen B and antibodies A in the plasma. 'AB' blood group contain both antigens A and B, but lack antibodies. Then there's the fourth blood group 'O', which lack antigens A or B, but contains antibodies A and B.

Now, for the next factor that differentiates blood groups: the Rhesus factor. The presence or absence of Rhesus factor further classifies blood types. So if a person has blood group A and shows presence of Rhesus factor, he or she is known to be Rh+ve and the blood group type is termed as A+ve. In case of absence of Rhesus factor, the person would have been Rh-ve and the blood group would have been A-ve. Similarly, all the other blood groups are categorized into negative and positive.

Blood Group Compatibility
Now, the next important thing to be known before understanding rare blood group types, is the blood group compatibility concept. Blood group compatibility is very important during blood transfusion. Not all blood groups are compatible with each other and when incompatible blood groups are mixed together clotting is caused. This can result in death of an individual. Thus, it is vital to find out which blood group is compatible with which type.

AB Group: Individuals with the blood group AB contain both antigen A and antigen B. Thus, they can receive blood from individuals of all blood groups. Nevertheless, people with AB blood group can donate blood only to people who have the AB blood group.

O Group: Individuals with this blood group do not contain antigen A or antigen B. Hence, they can donate blood to people who have A, B or AB blood group. However, they can receive blood only from individuals with blood group O.

A Group: Individuals with blood group A can receive blood from individuals who have the same blood group A or O, and can donate blood to people who have A or AB blood group.

B Group: Individuals with the blood group B can receive blood from individuals who have the blood group B or O and can donate blood to people who have B or AB blood group.

Apart from this, people who are Rh+ve can receive blood from people whose blood may be Rh+ve or Rh-ve, while people who are Rh-ve cannot receive blood from Rh+ve people. However, the Rhesus factor does not come into the picture when plasma is to be donated or received. Now, it makes sense why people with blood group O (especially O-ve) are referred to as 'universal donors' and people with blood group AB (especially AB+ve) are referred to as 'universal recipients'.

Rare Blood Types
Since we've understood the basics about blood groups and their compatibility, it is now time to understand rare blood types. Of the four basic blood groups, which blood group is termed rare and on what basis? Well, the meaning of rare blood type is that, it is present in very few individuals across the globe.

If we look at the statistics, AB negative blood group is the rarest blood type, with only 1 in about 170 Americans possessing this blood group. O-ve is also rare and of this category, the hh blood group, also called the Bombay blood group is extremely rare. This blood group is found in only 0.0004% of the world population. People with this blood group can donate to the ABO group, but can only receive blood from O-ve, hh blood group people.

Next in line is the B Negative blood type. About 1 in every 70 people has this blood type. A-ve is also rare. The most common blood group is the O+ve, which is a blessing because people with this blood type can donate blood to all people with Rh+ve blood group type.

Rare blood group is a concern when blood transfusion is to be done on a regular basis, for example in cases of patients with anemia, leukemia and other blood diseases. Usually, hospitals try and store rare blood groups in the blood bank, however, several times, rare blood group type is in shortage during dire need. The life of the patient, especially after an accident can be held at stake. Shortage also arises during war, bomb explosions, etc. wherein large number of emergency cases have to be tended to. Reserve blood may not suffice the requirement.

Thus, if people with rare blood groups could donate their blood on a regular basis, a lot of lives can be saved. Blood donation is safe and as the body destroys red blood cells every three months and makes new, if one could donate the blood, it would be very helpful to those in desperate need. The saddest part is that awareness about rare blood group types is still very low. Please help spread the word!